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How is heat load measured? Types of thermal loads

In the cold season in our country, the heating of buildings and structures is one of the main cost items of any enterprise. And here it does not matter whether it is a residential, industrial or warehouse space. Everywhere it is necessary to maintain a constant positive temperature so that people do not freeze, equipment does not fail, or products or materials do not deteriorate. In some cases, it is required to calculate the heat load for heating a particular building or the entire enterprise as a whole.

In what cases is the calculation of the heat load

to optimize heating costs;
to reduce the calculated heat load;
in the event that the composition of heat-consuming equipment has changed (heaters, ventilation systems, etc.);
to confirm the calculated limit on consumed heat energy;
in the case of designing your own heating system or heat supply point;
if there are sub-consumers consuming thermal energy, for its correct distribution;
In case of connection to the heating system of new buildings, structures, industrial complexes;
to revise or conclude a new contract with an organization supplying heat energy;
if the organization has received a notification requiring clarification of heat loads in non-residential premises;
if the organization has the opportunity to install heat meters;
in the event of an increase in heat consumption for unknown reasons.

On what basis can the heat load on the heating of the building be recalculated?

Order of the Ministry of Regional Development No. 610 dated December 28, 2009 "On approval of the rules for establishing and changing (revising) heat loads"() establishes the right of heat consumers to calculate and recalculate heat loads. Also, such a clause is usually present in every contract with a heat supply organization. If there is no such clause, discuss with your lawyers the issue of including it in the contract.

However, in order to revise the contractual amounts of consumed heat energy, a technical report must be submitted with the calculation of new heat loads for heating the building, in which justifications for reducing heat consumption must be given. In addition, the recalculation of thermal loads is carried out after such events as:

overhaul of the building;
reconstruction of internal engineering networks;
increasing the thermal protection of the facility;
other energy saving measures.

Method of calculation

To calculate or recalculate the heat load on the heating of buildings already in operation or newly connected to the heating system, the following work is carried out:

Collection of initial data about the object.
Conducting an energy audit of the building.
Based on the information obtained after the survey, the heat load for heating, hot water and ventilation is calculated.
Drawing up a technical report.
Coordination of the report in the organization providing heat energy.
Signing a new contract or changing the terms of an old one.

Collection of initial data on the heat load object

What data needs to be collected or received:

Agreement (copy) for heat supply with all annexes.
Help issued on letterhead on the actual number of employees (in the case of industrial buildings) or residents (in the case of a residential building).
BTI plan (copy).
Data on the heating system: one-pipe or two-pipe.
Top or bottom filling of the heat carrier.

All these data are required, because. based on them, the heat load will be calculated, as well as all the information will be included in the final report. The initial data, in addition, will help determine the timing and volume of work. The cost of the calculation is always individual and may depend on factors such as:

area of heated premises;
type of heating system;
availability of hot water supply and ventilation.

Energy audit of the building

Energy audit involves the departure of specialists directly to the facility. This is necessary in order to conduct a complete inspection of the heating system, to check the quality of its insulation. Also, during the departure, the missing data about the object are collected, which cannot be obtained except by means of a visual inspection. The types of heating radiators used, their location and number are determined. A diagram is drawn and photographs are attached. Be sure to inspect the supply pipes, measure their diameter, determine the material from which they are made, how these pipes are connected, where the risers are located, etc.

As a result of such an energy audit (energy audit), the customer will receive a detailed technical report, and on the basis of this report, the calculation of the heat loads for heating the building will already be carried out.

Technical report

The technical report on the heat load calculation should consist of the following sections:

Initial data about the object.
Scheme of the location of heating radiators.
DHW outlet points.
The calculation itself.
Conclusion based on the results of the energy audit, which should include comparison table maximum current thermal loads and contractual.
Applications.
1. Certificate of membership in the SRO energy auditor.
2. Floor plan of the building.
3. Explication.
4. All appendices to the contract for energy supply.

After drawing up, the technical report must be agreed with the heat supply organization, after which changes are made to the current contract or a new one is concluded.

An example of calculating the thermal loads of a commercial facility

This room is on the first floor of a 4-storey building. Location - Moscow.

Initial data for the object

Address of the object	Moscow
Floors of the building	4 floors
The floor on which the surveyed premises are located	first
The area of the surveyed premises	112.9 sq.m.
Floor height	3.0 m
Heating system	Single pipe
temperature graph	95-70 deg. With
Estimated temperature graph for the floor on which the room is located	75-70 deg. With
Bottling type	Upper
Estimated indoor air temperature	+ 20 degrees C
Heating radiators, type, quantity	Cast iron radiators M-140-AO - 6 pcs. Radiator bimetallic Global (Global) - 1 pc.
Diameter of pipes of the heating system	Du-25 mm
Heating supply line length	L = 28.0 m.
DHW	is absent
Ventilation	is absent
0.02/47.67 Gcal

Estimated heat transfer installed radiators heating, taking into account all losses, amounted to 0.007457 Gcal/h.

The maximum heat energy consumption for space heating was 0.001501 Gcal/h.

The final maximum consumption is 0.008958 Gcal/hour or 23 Gcal/year.

As a result, we calculate the annual savings for heating this room: 47.67-23 = 24.67 Gcal / year. Thus, it is possible to reduce the cost of heat energy by almost half. And if we take into account that the current average cost of Gcal in Moscow is 1.7 thousand rubles, then the annual savings in monetary terms will be 42 thousand rubles.

Calculation formula in Gcal

The calculation of the heat load on the heating of the building in the absence of heat meters is carried out according to the formula Q \u003d V * (T1 - T2) / 1000, where:

V- the volume of water consumed by the heating system is measured in tons or cubic meters,
T1- hot water temperature. It is measured in C (degrees Celsius) and the temperature corresponding to a certain pressure in the system is taken for calculations. This indicator has its own name - enthalpy. If it is impossible to accurately determine the temperature, then average values \u200b\u200bof 60-65 C are used.
T2- temperature cold water. Often it is almost impossible to measure it, and in this case constant indicators are used, which depend on the region. For example, in one of the regions, in the cold season, the indicator will be 5, in the warm season - 15.
1 000 - coefficient for obtaining the result of the calculation in Gcal.

For a heating system with a closed circuit, the heat load (Gcal / h) is calculated in a different way: Qot \u003d α * qo * V * (tin - tn.r) * (1 + Kn.r) * 0.000001, where:

α - a coefficient designed to correct climatic conditions. It is taken into account if the street temperature differs from -30 C;
V- the volume of the building according to external measurements;
qo- specific heating index of the building at a given tn.r = -30 C, measured in Kcal / m3 * C;
tv is the calculated internal temperature in the building;
tn.r- estimated street temperature for drafting a heating system;
Kn.r is the infiltration coefficient. It is due to the ratio of heat losses of the calculated building with infiltration and heat transfer through external structural elements at the street temperature, which is set within the framework of the project being drawn up.

Calculation for heating radiators per area

Enlarged calculation

If for 1 sq.m. area requires 100 W of thermal energy, then a room of 20 sq.m. should receive 2,000 watts. A typical eight-section radiator puts out about 150 watts of heat. We divide 2,000 by 150, we get 13 sections. But this is a rather enlarged calculation of the thermal load.

Accurate calculation

The exact calculation is carried out according to the following formula: Qt = 100 W/sq.m. × S(rooms) sq.m. × q1 × q2 × q3 × q4 × q5 × q6 × q7, where:

q1- type of glazing: ordinary = 1.27; double = 1.0; triple = 0.85;
q2– wall insulation: weak or absent = 1.27; wall laid out in 2 bricks = 1.0, modern, high = 0.85;
q3- the ratio of the total area window openings to floor area: 40% = 1.2; 30% = 1.1; 20% - 0.9; 10% = 0.8;
q4- minimum outdoor temperature: -35 C = 1.5; -25 C \u003d 1.3; -20 C = 1.1; -15 C \u003d 0.9; -10 C = 0.7;
q5- the number of external walls in the room: all four = 1.4, three = 1.3, corner room = 1.2, one = 1.2;
q6- type of design room above the design room: cold attic = 1.0, warm attic = 0.9, residential heated room = 0.8;
q7- ceiling height: 4.5 m = 1.2; 4.0 m = 1.15; 3.5 m = 1.1; 3.0 m = 1.05; 2.5 m = 1.3.

q - specific heating characteristic of the building, kcal / mh ° С is taken from the reference book, depending on the external volume of the building.

a is a correction factor taking into account the climatic conditions of the region, for Moscow, a = 1.08.

V - the outer volume of the building, m is determined by construction data.

t - the average air temperature inside the room, ° C is taken depending on the type of building.

t - design temperature of outdoor air for heating, °С for Moscow t= -28 °С.

Source: http://vunivere.ru/work8363

Q yh is made up of the thermal loads of devices serviced by water flowing through the site:

(3.1)

For the section of the supply heat pipeline, the thermal load expresses the heat reserve in the flowing hot water, intended for subsequent (on the further path of water) heat transfer to the premises. For the section of the return heat pipeline - the loss of heat by the flowing chilled water during heat transfer to the premises (on the previous water path). The thermal load of the site is designed to determine the flow of water in the site in the process of hydraulic calculation.

Water consumption on the site G uch at the calculated difference in water temperature in the system t g - t x, taking into account additional heat supply to the premises

where Q ych is the thermal load of the section, found by formula (3.1);

β 1 β 2 - correction factors that take into account additional heat supply to the premises;

c - specific mass heat capacity of water, equal to 4.187 kJ / (kg ° C).

To obtain the water flow in the area in kg / h, the heat load in W should be expressed in kJ / h, i.e. multiply by (3600/1000)=3.6.

as a whole is equal to the sum of heat loads of all heating devices (heat losses of rooms). According to the total heat demand for heating the building, the water flow in the heating system is determined.

Hydraulic calculation is associated with the thermal calculation of heating appliances and pipes. Multiple repetition of calculations is required to identify the actual flow and temperature of water, the required area of devices. When calculating manually, first perform a hydraulic calculation of the system, taking the average values of the local resistance coefficient (LFR) of the devices, then - the thermal calculation of pipes and devices.

If convectors are used in the system, the design of which includes pipes Dy15 and Dy20, then for a more accurate calculation, the length of these pipes is preliminarily determined, and after hydraulic calculation, taking into account the pressure losses in the pipes of the devices, having specified the flow rate and temperature of the water, they make adjustments to the dimensions of the devices.

Source: http://teplodoma.com.ua/1/gidravliheskiy_rashet/str_19.html

In this section, you will be able to get acquainted with the issues related to the calculation of heat losses and heat loads of a building in as much detail as possible.

The construction of heated buildings without heat loss calculation is prohibited!*)

And although most are still building at random, on the advice of a neighbor or godfather. It is right and clear to start at the stage of developing a working draft for construction. How it's done?

The architect (or the developer himself) provides us with a list of "available" or "priority" materials for arranging walls, roofs, bases, which windows, doors are planned.

Already at the design stage of a house or building, as well as for the selection of heating, ventilation, air conditioning systems, it is necessary to know the heat losses of the building.

Calculation of heat loss for ventilation we often use in our practice to calculate the economic feasibility of modernizing and automating the ventilation / air conditioning system, because calculation of heat losses for ventilation gives a clear idea of the benefits and payback period of funds invested in energy-saving measures (automation, use of recuperation, insulation of air ducts, frequency controllers).

Calculation of building heat losses

This is the basis for the competent selection of the power of heating equipment (boiler, boiler) and heating appliances

The main heat losses of a building usually occur in the roof, walls, windows and floors. A sufficiently large part of the heat leaves the premises through the ventilation system.

Rice. 1 Building heat loss

The main factors affecting heat loss in a building are the temperature difference between indoors and outdoors (the greater the difference, the greater the body loss) and the thermal insulation properties of building envelopes (foundation, walls, ceilings, windows, roofing).

Fig. 2 Thermal imaging survey of building heat losses

Enclosing materials prevent the penetration of heat from the premises to the outside in winter and the penetration of heat into the premises in summer, because the selected materials must have certain thermal insulation properties, which are denoted by a value called - heat transfer resistance.

The resulting value will show what the real temperature difference will be when a certain amount of heat passes through 1m² of a particular building envelope, as well as how much heat will leave after 1m² at a certain temperature difference.

#image.jpgHow heat loss is calculated

When calculating the heat losses of a building, we will be mainly interested in all external enclosing structures and the location of internal partitions.

To calculate heat losses along the roof, it is also necessary to take into account the shape of the roof and the presence of an air gap. There are also some nuances in the thermal calculation of the floor of the room.

To obtain the most accurate value of the heat loss of a building, it is necessary to take into account absolutely all enclosing surfaces (foundation, floors, walls, roof), their constituent materials and the thickness of each layer, as well as the position of the building relative to the cardinal points and climatic conditions in the region.

To order the calculation of heat losses you need fill out our questionnaire and we will send our commercial offer to the specified postal address as soon as possible (no more than 2 working days).

Scope of work on the calculation of thermal loads of the building

The main composition of the documentation for the calculation of the thermal load of the building:

building heat loss calculation
calculation of heat losses for ventilation and infiltration
permits
summary table of thermal loads

The cost of calculating the thermal loads of the building

The cost of services for calculating the thermal loads of a building does not have a single price, the price for the calculation depends on many factors:

heated area;
availability of project documentation;
architectural complexity of the object;
composition of enclosing structures;
the number of heat consumers;
the diversity of the purpose of the premises, etc.

It is not difficult to find out the exact cost and order a service for calculating the heat load of a building, for this you just need to send us a floor plan of the building by e-mail (form), fill out a short questionnaire and after 1 working day you will receive our commercial offer to your mailbox.

#image.jpgExamples of the cost of calculating thermal loads

Thermal calculations for a private house

Documentation set:

- calculation of heat losses (room by room, floor by floor, infiltration, total)

- calculation of heat load for hot water heating (DHW)

- calculation for heating air from the street for ventilation

A package of thermal documents will cost in this case - 1600 UAH

For such calculations bonus You are getting:

Recommendations for insulation and elimination of cold bridges

Power selection of the main equipment

_____________________________________________________________________________________

The sports complex is a detached 4-storey building of a typical construction, with a total area of 2100 sq.m. with a large gym, heated supply and exhaust ventilation system, radiator heating, a full set of documentation — 4200.00 UAH

_____________________________________________________________________________________

Shop - a premise built into a residential building on the 1st floor, with a total area of 240 sq.m. of which 65 sq.m. warehouses, without basement, radiator heating, heated supply and exhaust ventilation with heat recovery — 2600.00 UAH

______________________________________________________________________________________

Terms of performance of work on the calculation of thermal loads

The term for performing work on the calculation of the thermal loads of the building mainly depends on the following components:

total heated area of premises or building
architectural complexity of the object
complexity or multi-layered enclosing structures
number of heat consumers: heating, ventilation, hot water, other
versatility of premises (warehouse, offices, shopping room, residential, etc.)
organization of a heat energy commercial metering unit
completeness of the availability of documentation (project of heating, ventilation, executive schemes for heating, ventilation, etc.)
diversity of use of building envelope materials in construction
complexity of the ventilation system (recuperation, automatic control system, zone temperature control)

In most cases, for a building with a total area of not more than 2000 sq.m. The term for calculating the thermal loads of a building is 5 to 21 business days depending on the above characteristics of the building, provided documentation and engineering systems.

Coordination of calculation of heat loads in heat networks

After completing all the work on the calculation of thermal loads and collecting all required documents we are approaching the final, but difficult issue of coordinating the calculation of heat loads in urban heating networks. This process is a "classic" example of communication with state structure, is notable for the mass of interesting innovations, clarifications, views, interests of the subscriber (client) or the representative of the contracting organization (which has undertaken the obligation to coordinate the calculation of heat loads in heating networks) with representatives of urban heating networks. In general, the process is often difficult, but surmountable.

The list of documents to be submitted for approval looks something like this:

Application (written directly in thermal networks);
Calculation of thermal loads (in full);
License, list of licensed works and services of the contractor performing the calculations;
Registration certificate for the building or premises;
The right establishing the documentation for the ownership of the object, etc.

Usually for term for approval of the calculation of thermal loads accepted - 2 weeks (14 working days) subject to the submission of documentation in full and in the required form.

Services for calculating the thermal loads of the building and related tasks

When concluding or re-executing an agreement on the supply of heat from city heating networks or designing and installing a commercial heat metering unit, heating networks notify the owner of the building (premises) of the need to:

get technical conditions (TU);
provide a calculation of the thermal load of the building for approval;
project for the heating system;
project for the ventilation system;
and etc.

We offer our services for carrying out the necessary calculations, designing heating systems, ventilation and subsequent approvals in urban heating networks and other regulatory authorities.

You can order both a separate document, project or calculation, as well as execution of all necessary documents on a turnkey basis from any stage.

Discuss the topic and leave feedback: "CALCULATION OF HEAT LOSSES AND LOADS" on FORUM #image.jpg

We will be glad to continue cooperation with you by offering:

Supply of equipment and materials at wholesale prices

Design work

Assembly / installation / commissioning

Further maintenance and provision of services at reduced prices (for regular customers)

1. Heating

1.1. The estimated hourly heat load of heating should be taken according to standard or individual building designs.

If the value of the calculated outdoor air temperature adopted in the project for designing heating differs from the current standard value for a particular area, it is necessary to recalculate the estimated hourly heat load of the heated building given in the project according to the formula:

where Qo max is the calculated hourly heat load of the heating of the building, Gcal/h;

Qo max pr - the same, according to a standard or individual project, Gcal / h;

tj - design air temperature in the heated building, °С; taken in accordance with Table 1;

to - design outdoor air temperature for designing heating in the area where the building is located, according to SNiP 23-01-99, ° С;

to.pr - the same, according to a standard or individual project, °С.

Table 1. Estimated air temperature in heated buildings

In areas with an estimated outdoor air temperature for heating design of -31 °С and below, the value of the calculated air temperature inside heated residential buildings should be taken in accordance with the chapter SNiP 2.08.01-85 equal to 20 °С.

1.2. In the absence of design information, the estimated hourly heat load of heating an individual building can be determined by aggregated indicators:

where  is a correction factor that takes into account the difference in the calculated outdoor temperature for heating design to from to = -30 °С, at which the corresponding qo value is determined; taken according to table 2;

V is the volume of the building according to the external measurement, m3;

qo - specific heating characteristic of the building at to = -30 °С, kcal/m3 h°С; taken according to tables 3 and 4;

Ki.r - design factor infiltration due to thermal and wind pressure, i.e. the ratio of heat losses from a building with infiltration and heat transfer through external fences at an outside air temperature calculated for heating design.

Table 2. Correction factor  for residential buildings

Table 3. Specific heating characteristic of residential buildings

External building volume V, m3	Specific heating characteristic qo, kcal/m3 h °C
building before 1958	building after 1958

Table 3a. Specific heating characteristic of buildings built before 1930

Table 4. Specific thermal characteristic of administrative, medical, cultural and educational buildings, children's institutions

Name of buildings	Volume of buildings V, m3	Specific thermal characteristics
for heating qo, kcal/m3 h °C	for ventilation qv, kcal/m3 h °C

Administrative buildings, offices


	over 15000


	over 10000
Cinemas

	over 10000




	over 30000
The shops

	over 10000
Kindergartens and nurseries

Schools and higher education institutions

	over 10000
Hospitals


	over 15000


	over 10000
Laundries

	over 10000
Catering establishments, canteens, kitchen factories

	over 10000
Laboratories

	over 10000
fire stations

The value of V, m3, should be taken according to the information of a typical or individual design of a building or a technical inventory bureau (BTI).

If the building has an attic floor, the value V, m3, is determined as the product of the horizontal cross-sectional area of the building at the level of its first floor (above the basement floor) and the free height of the building - from the level of the finished floor of the first floor to the upper plane of the attic floor heat-insulating layer, with roofs, combined with attic ceilings - up to the average mark of the top of the roof. Protruding beyond the surface of the walls architectural details and niches in the walls of the building, as well as unheated loggias, when determining the estimated hourly heat load of heating, are not taken into account.

If there is a heated basement in the building, 40% of the volume of this basement must be added to the resulting volume of the heated building. Construction volume of the underground part of the building (basement, ground floor) is defined as the product of the area of the horizontal section of the building at the level of its first floor and the height of the basement (ground floor).

The calculated infiltration coefficient Ki.r is determined by the formula:

where g - free fall acceleration, m/s2;

L - free height of the building, m;

w0 - calculated wind speed for the given area during the heating season, m/s; accepted according to SNiP 23-01-99.

It is not necessary to enter into the calculation of the calculated hourly heat load of the heating of the building the so-called correction for the effect of wind, because. this quantity has already been taken into account in formula (3.3).

In areas where the design value of the outdoor air temperature for heating design is up to  -40 °С, for buildings with unheated basements, additional heat losses through the unheated floors of the first floor in the amount of 5% should be taken into account.

For buildings completed by construction, the calculated hourly heat load of heating should be increased for the first heating period for stone buildings built:

In May-June - by 12%;

In July-August - by 20%;

In September - by 25%;

In the heating period - by 30%.

1.3. The specific heating characteristic of a building qo, kcal/m3 h °C, in the absence of a qo value corresponding to its construction volume in Tables 3 and 4, can be determined by the formula:

where a \u003d 1.6 kcal / m 2.83 h ° С; n = 6 - for buildings under construction before 1958;

a \u003d 1.3 kcal / m 2.875 h ° С; n = 8 - for buildings under construction after 1958

1.4. If a part of a residential building is occupied by a public institution (office, shop, pharmacy, laundry collection point, etc.), the estimated hourly heating load must be determined according to the project. If the calculated hourly heat load in the project is indicated only for the whole building, or is determined by aggregated indicators, the heat load of individual rooms can be determined by the heat exchange surface area of the installed heating devices using general equation describing their heat transfer:

Q = k F t, (3.5)

where k is the heat transfer coefficient of the heating device, kcal/m3 h °C;

F - heat exchange surface area of the heating device, m2;

t - temperature difference of the heating device, °С, defined as the difference between the average temperature of the convective-radiative heating device and the air temperature in the heated building.

The methodology for determining the calculated hourly heat load of heating on the surface of installed heating devices of heating systems is given in.

1.5. When heated towel rails are connected to the heating system, the calculated hourly heat load of these heaters can be determined as the heat transfer of uninsulated pipes in a room with an estimated air temperature tj \u003d 25 ° C according to the method given in.

1.6. In the absence of design data and the determination of the estimated hourly heat load for heating industrial, public, agricultural and other non-standard buildings (garages, heated underground passages, swimming pools, shops, kiosks, pharmacies, etc.) according to aggregated indicators, the values of this load should be refined according to the heat exchange surface area of the installed heating devices of heating systems in accordance with the methodology given in. Initial information for calculations is revealed by the representative heat supply organization in the presence of a representative of the subscriber with the preparation of the relevant act.

1.7. The consumption of thermal energy for the technological needs of greenhouses and conservatories, Gcal/h, is determined from the expression:

, (3.6)

where Qcxi is the consumption of thermal energy for i-e technological operations, Gcal/h;

n is the number of technological operations.

In its turn,

Qcxi \u003d 1.05 (Qtp + Qv) + Qfloor + Qprop, (3.7)

where Qtp and Qv are heat losses through the building envelope and during air exchange, Gcal/h;

Qpol + Qprop - consumption of thermal energy for heating irrigation water and steaming the soil, Gcal/h;

1.05 - coefficient taking into account the consumption of thermal energy for heating domestic premises.

1.7.1. Heat loss through building envelope, Gcal/h, can be determined by the formula:

Qtp = FK (tj - to) 10-6, (3.8)

where F is the surface area of the building envelope, m2;

K is the heat transfer coefficient of the enclosing structure, kcal/m2 h °C; for single glazing, K = 5.5 can be taken, for a single-layer film fence K = 7.0 kcal / m2 h ° C;

tj and to are the process temperature in the room and the calculated outdoor air for the design of the corresponding agricultural facility, °С.

1.7.2. Heat losses during air exchange for greenhouses with glass coatings, Gcal/h, are determined by the formula:

Qv \u003d 22.8 Finv S (tj - to) 10-6, (3.9)

where Finv is the inventory area of the greenhouse, m2;

S - volume coefficient, which is the ratio of the volume of the greenhouse and its inventory area, m; can be taken in the range from 0.24 to 0.5 for small greenhouses and 3 or more m - for hangars.

Heat losses during air exchange for film-coated greenhouses, Gcal/h, are determined by the formula:

Qv \u003d 11.4 Finv S (tj - to) 10-6. (3.9a)

1.7.3. The consumption of thermal energy for heating irrigation water, Gcal/h, is determined from the expression:

, (3.10)

where Fcreep is the useful area of the greenhouse, m2;

n - duration of watering, h.

1.7.4. The consumption of thermal energy for steaming the soil, Gcal/h, is determined from the expression:

2. Supply ventilation

2.1. If there is a standard or individual design of the building and the compliance of the installed equipment of the supply ventilation system with the project, the calculated hourly heat load of ventilation can be taken according to the project, taking into account the difference in the values of the calculated outdoor temperature for designing ventilation adopted in the project, and the current standard value for the area where the considered building.

Recalculation is carried out according to a formula similar to formula (3.1):

, (3.1a)

Qv.pr - the same, according to the project, Gcal / h;

tv.pr is the calculated outdoor air temperature at which the heat load of supply ventilation in the project is determined, °С;

tv is the calculated outdoor air temperature for designing supply ventilation in the area where the building is located, °С; accepted according to the instructions of SNiP 23-01-99.

2.2. In the absence of projects or inconsistency of the installed equipment with the project, the calculated hourly heat load of supply ventilation must be determined from the characteristics of the equipment actually installed, in accordance with the general formula describing the heat transfer of air heaters:

Q = Lc (2 + 1) 10-6, (3.12)

where L is the volumetric flow rate of heated air, m3/h;

 - density of heated air, kg/m3;

c is the heat capacity of the heated air, kcal/kg;

2 and 1 - calculated values of air temperature at the inlet and outlet of the calorific unit, °С.

The methodology for determining the estimated hourly heat load of supply air heaters is set out in.

It is permissible to determine the calculated hourly heat load of supply ventilation public buildings according to aggregated indicators according to the formula:

Qv \u003d Vqv (tj - tv) 10-6, (3.2a)

where qv is the specific thermal ventilation characteristic of the building, depending on the purpose and construction volume of the ventilated building, kcal/m3 h °C; can be taken from Table 4.

3. Hot water supply

3.1. The average hourly heat load of hot water supply of a consumer of thermal energy Qhm, Gcal/h, during the heating period is determined by the formula:

where a is the rate of water consumption for hot water supply of the subscriber, l / unit. measurements per day; must be approved by the local government; in the absence of approved norms, it is adopted according to the table of Appendix 3 (mandatory) SNiP 2.04.01-85;

N - the number of units of measurement, referred to the day, - the number of residents, students in educational institutions, etc.;

tc - tap water temperature during the heating season, °С; in the absence of reliable information, tc = 5 °С is accepted;

T - the duration of the operation of the hot water supply system of the subscriber per day, h;

Qt.p - heat losses in the local hot water supply system, in the supply and circulation pipelines outdoor network hot water supply, Gcal/h.

3.2. The average hourly heat load of hot water supply in the non-heating period, Gcal, can be determined from the expression:

, (3.13a)

where Qhm is the average hourly heat load of hot water supply during the heating period, Gcal/h;

 - coefficient taking into account the decrease in the average hourly load of hot water supply in the non-heating period compared to the load in the heating period; if the value of  is not approved by the authority local government,  is taken equal to 0.8 for the housing and communal sector of cities in central Russia, 1.2-1.5 - for resorts, southern cities and towns, for enterprises - 1.0;

ths, th - hot water temperature in non-heating and heating periods, °C;

tcs, tc - tap water temperature during the non-heating and heating period, °C; in the absence of reliable information, tcs = 15 °С, tc = 5 °С are accepted.

3.3. Heat losses by pipelines of the hot water supply system can be determined by the formula:

where Ki is the heat transfer coefficient of a section of an uninsulated pipeline, kcal/m2 h °C; you can take Ki = 10 kcal/m2 h °C;

di and li - diameter of the pipeline in the section and its length, m;

tн and tк - temperature of hot water at the beginning and end of the calculated section of the pipeline, °С;

tamb - ambient temperature, °С; take the form of laying pipelines:

In furrows, vertical channels, communication shafts of sanitary cabins tacr = 23 °С;

In bathrooms tamb = 25 °С;

In kitchens and toilets tamb = 21 °С;

On stairwells tocr = 16 °С;

In the underground laying channels of the external hot water supply network tcr = tgr;

In tunnels tcr = 40 °С;

In unheated basements tocr = 5 °С;

In attics tambi = -9 °С (at the average outdoor temperature of the coldest month of the heating period tн = -11 ... -20 °С);

 - efficiency of thermal insulation of pipelines; accepted for pipelines with a diameter of up to 32 mm  = 0.6; 40-70 mm  = 0.74; 80-200 mm  = 0.81.

Table 5. Specific heat losses of pipelines of hot water supply systems (according to the place and method of laying)

Place and method of laying	Thermal losses of the pipeline, kcal / hm, with a nominal diameter, mm


Main supply riser in a ditch or communication shaft, insulated
Riser without heated towel rails, insulated, in the sanitary cabin shaft, furrow or utility shaft
Same with towel rails.
Riser uninsulated in the sanitary cabin shaft, furrow or communication shaft or open in the bathroom, kitchen
Distribution insulated pipelines (supply):
in the basement, stairwell
in a cold attic
in a warm attic
Circulation pipelines isolated:
in the basement
in a warm attic
in a cold attic
Circulation pipelines uninsulated:
in apartments
on the stairwell
Circulation risers in the duct of a sanitary cabin or bathroom:
isolated
uninsulated

Note. In the numerator - specific heat losses of pipelines of hot water supply systems without direct water intake in heat supply systems, in the denominator - with direct water intake.

Table 6. Specific heat losses of pipelines of hot water supply systems (by temperature difference)

Temperature drop, °С

Thermal losses of the pipeline, kcal / h m, with a nominal diameter, mm

Note. If the hot water temperature difference is different from its given values, the specific heat losses should be determined by interpolation.

3.4. With absence background information required to calculate heat losses by hot water supply pipelines, heat losses, Gcal/h, can be determined by applying a special coefficient Kt.p, taking into account the heat losses of these pipelines, according to the expression:

Qt.p = Qhm Kt.p. (3.15)

The heat flow to hot water supply, taking into account heat losses, can be determined from the expression:

Qg = Qhm (1 + Kt.p). (3.16)

Table 7 can be used to determine the values of the coefficient Kt.p.

Table 7. Coefficient taking into account heat losses by pipelines of hot water supply systems

studfiles.net

How to calculate the heat load for heating a building

In houses that have been put into operation in recent years, these rules are usually met, so the calculation of the heating power of the equipment is based on standard coefficients. An individual calculation can be carried out at the initiative of the owner of the housing or the communal structure involved in the supply of heat. This happens when spontaneous replacement of heating radiators, windows and other parameters.

See also: How to calculate the power of a heating boiler by area of \u200b\u200bthe house

Calculation of norms for heating in an apartment

In an apartment served by a utility company, the calculation of the heat load can only be carried out upon transfer of the house in order to track the parameters of SNIP in the premises taken on balance. Otherwise, the owner of the apartment does this in order to calculate his heat losses in the cold season and eliminate the shortcomings of insulation - use heat-insulating plaster, glue insulation, mount penofol on the ceilings and install metal-plastic windows with a five-chamber profile.

The calculation of heat leaks for the public utility in order to open a dispute, as a rule, does not give a result. The reason is that there are heat loss standards. If the house is put into operation, then the requirements are met. At the same time, heating devices comply with the requirements of SNIP. Replacing batteries and extracting more heat is prohibited, as the radiators are installed according to approved building standards.

The method of calculating the norms for heating in a private house

Private houses are heated by autonomous systems, which at the same time calculates the load is carried out to comply with the requirements of SNIP, and the correction of heating power is carried out in conjunction with work to reduce heat loss.

Calculations can be done manually using a simple formula or a calculator on the website. The program helps to calculate the required capacity of the heating system and heat leakage, typical for the winter period. Calculations are carried out for a certain thermal zone.

Basic principles

The methodology includes a number of indicators that together allow us to assess the level of insulation of the house, compliance with SNIP standards, as well as the power of the heating boiler. How it works:

depending on the parameters of walls, windows, insulation of the ceiling and foundation, you calculate heat leakage. For example, your wall consists of a single layer of clinker bricks and frame bricks with insulation, depending on the thickness of the walls, they have a certain thermal conductivity in combination and prevent heat from escaping in winter. Your task is to ensure that this parameter is not less than recommended in SNIP. The same is true for the foundation, ceilings and windows;
find out where heat is lost, bring the parameters to standard ones;
calculate the power of the boiler based on the total volume of rooms - for every 1 cubic meter. m of the room takes 41 W of heat (for example, a hallway of 10 m² with a ceiling height of 2.7 m requires 1107 W of heating, two 600 W batteries are needed);
you can calculate from the opposite, that is, from the number of batteries. Each section of the aluminum battery gives 170 W of heat and heats 2-2.5 m of the room. If your house requires 30 battery sections, then the boiler that can heat the room must be at least 6 kW.

The worse the house is insulated, the higher the heat consumption from the heating system

An individual or average calculation is carried out for the object. The main point of conducting such a survey is that with good insulation and low heat leakage in winter, 3 kW can be used. In a building of the same area, but without insulation, at low winter temperatures, the power consumption will be up to 12 kW. Thus, the thermal power and load are estimated not only by area, but also by heat loss.

The main heat loss of a private house:

windows - 10-55%;
walls - 20-25%;
chimney - up to 25%;
roof and ceiling - up to 30%;
low floors - 7-10%;
temperature bridge in the corners - up to 10%

These indicators can vary for better and worse. They are evaluated depending on the types of windows installed, the thickness of the walls and materials, the degree of insulation of the ceiling. For example, in poorly insulated buildings, heat loss through walls can reach 45% percent, in which case the expression “we drown the street” is applicable to the heating system. Methodology and The calculator will help you evaluate the nominal and calculated values.

Specificity of calculations

This technique can still be found under the name "thermal calculation". The simplified formula looks like this:

Qt = V × ∆T × K / 860, where

V is the volume of the room, m³;

∆T is the maximum difference between indoors and outdoors, °С;

K is the estimated heat loss coefficient;

860 is the conversion factor in kWh.

The heat loss coefficient K depends on building structure, wall thickness and thermal conductivity. For simplified calculations, you can use the following parameters:

K \u003d 3.0-4.0 - without thermal insulation (non-insulated frame or metal structure);
K \u003d 2.0-2.9 - low thermal insulation (laying in one brick);
K \u003d 1.0-1.9 - average thermal insulation (brickwork in two bricks);
K \u003d 0.6-0.9 - good thermal insulation according to the standard.

These coefficients are averaged and do not allow estimating heat loss and heat load on the room, so we recommend using the online calculator.

gidpopechi.ru

Calculation of the heat load on the heating of a building: formula, examples

When designing a heating system, whether it is an industrial building or a residential building, it is necessary to carry out competent calculations and draw up a diagram of the heating system circuit. At this stage, experts recommend paying special attention to the calculation of the possible heat load on the heating circuit, as well as the amount of fuel consumed and heat generated.

This term refers to the amount of heat given off by heating devices. The carried out preliminary calculation of the heat load will allow avoiding unnecessary costs for the purchase of components of the heating system and for their installation. Also, this calculation will help to correctly distribute the amount of heat generated economically and evenly throughout the building.

There are many nuances in these calculations. For example, the material from which the building is built, thermal insulation, region, etc. Experts try to take into account as many factors and characteristics as possible to obtain a more accurate result.

The calculation of the heat load with errors and inaccuracies leads to inefficient operation of the heating system. It even happens that you have to redo sections of an already working structure, which inevitably leads to unplanned expenses. Yes, and housing and communal organizations calculate the cost of services based on data on heat load.

Main Factors

An ideally calculated and designed heating system must maintain the set temperature in the room and compensate for the resulting heat losses. When calculating the indicator of the heat load on the heating system in the building, you need to take into account:

Purpose of the building: residential or industrial.

Characteristics of the structural elements of the structure. These are windows, walls, doors, roof and ventilation system.

Housing dimensions. The larger it is, the more powerful the heating system should be. Be sure to take into account the area of window openings, doors, exterior walls and the volume of each interior space.

The presence of rooms for special purposes (bath, sauna, etc.).

Degree of equipment with technical devices. That is, the presence of hot water supply, ventilation systems, air conditioning and the type of heating system.

Temperature regime for a single room. For example, in rooms intended for storage, it is not necessary to maintain a comfortable temperature for a person.

Number of points with hot water supply. The more of them, the more the system is loaded.

Area of glazed surfaces. Rooms with French windows lose a significant amount of heat.

Additional terms. In residential buildings, this can be the number of rooms, balconies and loggias and bathrooms. In industrial - the number of working days in a calendar year, shifts, the technological chain of the production process, etc.

Climatic conditions of the region. When calculating heat losses, street temperatures are taken into account. If the differences are insignificant, then a small amount of energy will be spent on compensation. While at -40 ° C outside the window it will require significant expenses.

Features of existing methods

The parameters included in the calculation of the heat load are in SNiPs and GOSTs. They also have special heat transfer coefficients. From the passports of the equipment included in the heating system, digital characteristics are taken regarding a specific heating radiator, boiler, etc. And also traditionally:

The heat consumption, taken to the maximum for one hour of operation of the heating system,

The maximum heat flow from one radiator,

Total heat costs in a certain period (most often - a season); if you need an hourly calculation of the load on heating network, then the calculation must be carried out taking into account the temperature difference during the day.

The calculations made are compared with the heat transfer area of the entire system. The index is quite accurate. Some deviations happen. For example, for industrial buildings, it will be necessary to take into account the reduction in heat energy consumption on weekends and holidays, and in residential buildings - at night.

Methods for calculating heating systems have several degrees of accuracy. To reduce the error to a minimum, it is necessary to use rather complex calculations. Less accurate schemes are used if the goal is not to optimize the costs of the heating system.

Basic calculation methods

To date, the calculation of the heat load on the heating of a building can be carried out in one of the following ways.

Three main

Aggregated indicators are taken for calculation.
The indicators of the structural elements of the building are taken as the base. Here, it will be important to calculate the heat loss used to heat the internal volume of air.
All objects included in the heating system are calculated and summarized.

One exemplary

There is also a fourth option. It has a fairly large error, because the indicators are taken very average, or they are not enough. Here is the formula - Qot \u003d q0 * a * VH * (tEN - tHRO), where:

q0 - specific thermal characteristic of the building (most often determined by the coldest period),
a - correction factor (depends on the region and is taken from ready-made tables),
VH is the volume calculated from the outer planes.

Example of a simple calculation

For a building with standard parameters (ceiling heights, room sizes and good thermal insulation characteristics) you can apply a simple ratio of parameters, corrected by a factor depending on the region.

Suppose that a residential building is located in the Arkhangelsk region, and its area is 170 square meters. m. The heat load will be equal to 17 * 1.6 \u003d 27.2 kW / h.

Such a definition of thermal loads does not take into account many important factors. For example, design features buildings, temperatures, the number of walls, the ratio of the areas of walls and window openings, etc. Therefore, such calculations are not suitable for serious heating system projects.

Calculation of a heating radiator by area

It depends on the material from which they are made. Most often today, bimetallic, aluminum, steel are used, much less often cast iron radiators. Each of them has its own heat transfer index (thermal power). Bimetal radiators with a distance between the axes of 500 mm, on average they have 180 - 190 watts. Aluminum radiators have almost the same performance.

The heat transfer of the described radiators is calculated for one section. Steel plate radiators are non-separable. Therefore, their heat transfer is determined based on the size of the entire device. For example, the thermal power of a two-row radiator 1,100 mm wide and 200 mm high will be 1,010 W, and a steel panel radiator 500 mm wide and 220 mm high will be 1,644 W.

The calculation of the heating radiator by area includes the following basic parameters:

Ceiling height (standard - 2.7 m),

Thermal power (per sq. m - 100 W),

One outer wall.

These calculations show that for every 10 sq. m requires 1,000 W of thermal power. This result is divided by the heat output of one section. The answer is required amount radiator sections.

For the southern regions of our country, as well as for the northern ones, decreasing and increasing coefficients have been developed.

Average calculation and exact

Given the factors described, the average calculation is carried out according to the following scheme. If for 1 sq. m requires 100 W of heat flow, then a room of 20 square meters. m should receive 2,000 watts. A radiator (popular bimetallic or aluminum) of eight sections emits about 150 watts. We divide 2,000 by 150, we get 13 sections. But this is a rather enlarged calculation of the thermal load.

The exact one looks a little intimidating. Actually, nothing complicated. Here is the formula:

Qt = 100 W/m2 × S(room)m2 × q1 × q2 × q3 × q4 × q5 × q6 × q7, where:

q1 - type of glazing (ordinary = 1.27, double = 1.0, triple = 0.85);
q2 – wall insulation (weak or absent = 1.27, 2-brick wall = 1.0, modern, high = 0.85);
q3 - the ratio of the total area of window openings to the floor area (40% = 1.2, 30% = 1.1, 20% - 0.9, 10% = 0.8);
q4 - outdoor temperature (the minimum value is taken: -35оС = 1.5, -25оС = 1.3, -20оС = 1.1, -15оС = 0.9, -10оС = 0.7);
q5 - the number of external walls in the room (all four = 1.4, three = 1.3, corner room = 1.2, one = 1.2);
q6 - type of design room above the design room (cold attic = 1.0, warm attic = 0.9, residential heated room = 0.8);
q7 - ceiling height (4.5 m = 1.2, 4.0 m = 1.15, 3.5 m = 1.1, 3.0 m = 1.05, 2.5 m = 1.3).

Using any of the methods described, it is possible to calculate the heat load of an apartment building.

Approximate calculation

These are the conditions. Minimum temperature in the cold season - -20оС. Room 25 sq. m with triple glazing, double-leaf windows, ceiling height of 3.0 m, two-brick walls and an unheated attic. The calculation will be as follows:

Q = 100 W/m2 × 25 m2 × 0.85 × 1 × 0.8(12%) × 1.1 × 1.2 × 1 × 1.05.

The result, 2 356.20, is divided by 150. As a result, it turns out that 16 sections need to be installed in a room with the specified parameters.

If calculation is required in gigacalories

In the absence of a heat energy meter on an open heating circuit, the calculation of the heat load for heating the building is calculated by the formula Q = V * (T1 - T2) / 1000, where:

V - the amount of water consumed by the heating system, calculated in tons or m3,
T1 - a number indicating the temperature of hot water, measured in ° C, and for calculations, the temperature corresponding to a certain pressure in the system is taken. This indicator has its own name - enthalpy. If it is not possible to remove temperature indicators in a practical way, they resort to an average indicator. It is in the range of 60-65oC.
T2 is the temperature of cold water. It is quite difficult to measure it in the system, so constant indicators have been developed that depend on temperature regime on the street. For example, in one of the regions, in the cold season, this indicator is taken equal to 5, in summer - 15.
1,000 is the coefficient for obtaining the result immediately in gigacalories.

In the case of a closed circuit, the heat load (gcal/h) is calculated differently:

Qot \u003d α * qo * V * (tin - tn.r) * (1 + Kn.r) * 0.000001, where

α is a coefficient designed to correct climatic conditions. It is taken into account if the street temperature differs from -30 ° C;
V - the volume of the building according to external measurements;
qo - specific heating index of the structure at a given tn.r = -30 ° C, measured in kcal / m3 * C;
tv is the calculated internal temperature in the building;
tn.r - estimated street temperature for drafting a heating system;
Kn.r – infiltration coefficient. It is due to the ratio of heat losses of the calculated building with infiltration and heat transfer through external structural elements at the street temperature, which is set within the framework of the project being drawn up.

The calculation of the heat load turns out to be somewhat enlarged, but it is this formula that is given in the technical literature.

Inspection with a thermal imager

Increasingly, in order to increase the efficiency of the heating system, they resort to thermal imaging surveys of the building.

These works are carried out at night. For a more accurate result, you must observe the temperature difference between the room and the street: it must be at least 15 °. Fluorescent and incandescent lamps are switched off. It is advisable to remove carpets and furniture to the maximum, they knock down the device, giving some error.

The survey is carried out slowly, the data are recorded carefully. The scheme is simple.

The first stage of work takes place indoors. The device is moved gradually from doors to windows, paying special attention to corners and other joints.

The second stage is the examination of the external walls of the building with a thermal imager. The joints are still carefully examined, especially the connection with the roof.

The third stage is data processing. First, the device does this, then the readings are transferred to a computer, where the corresponding programs complete the processing and give the result.

If the survey was conducted by a licensed organization, then it will issue a report with mandatory recommendations based on the results of the work. If the work was carried out personally, then you need to rely on your knowledge and, possibly, the help of the Internet.

highlogistic.ru

Calculation of the heat load for heating: how to correctly perform?

The first and most important stage in the difficult process of organizing the heating of any real estate object (whether it be a country house or an industrial facility) is the competent design and calculation. In particular, it is necessary to calculate the heat loads on the heating system, as well as the volume of heat and fuel consumption.

Thermal loads

Performing preliminary calculations is necessary not only in order to obtain the entire range of documentation for organizing the heating of a property, but also to understand the volumes of fuel and heat, the selection of one or another type of heat generators.

Thermal loads of the heating system: characteristics, definitions

The definition of “heat load on heating” should be understood as the amount of heat that is collectively given off by heating devices installed in a house or other facility. It should be noted that before installing all the equipment, this calculation is made to exclude any troubles, unnecessary financial costs and work.

Calculation of heat loads for heating will help to organize uninterrupted and efficient work real estate heating systems. Thanks to this calculation, you can quickly complete absolutely all the tasks of heat supply, ensure their compliance with the norms and requirements of SNiP.

A set of instruments for performing calculations

The cost of an error in the calculation can be quite significant. The thing is that, depending on the calculated data received, the maximum expenditure parameters will be allocated in the housing and communal services department of the city, limits and other characteristics will be set, from which they are repelled when calculating the cost of services.

The total heat load on a modern heating system consists of several main load parameters:

For a common central heating system;
On the floor heating system (if available in the house) - underfloor heating;
Ventilation system (natural and forced);
Hot water supply system;
For all kinds of technological needs: swimming pools, baths and other similar structures.

Calculation and components of thermal systems at home

The main characteristics of the object, important to take into account when calculating the heat load

The most correctly and competently calculated heat load on heating will be determined only when absolutely everything, even the smallest details and parameters, is taken into account.

This list is quite large and can include:

Type and purpose of real estate objects. A residential or non-residential building, an apartment or an administrative building - all this is very important for obtaining reliable thermal calculation data.

Also, the load rate, which is determined by heat supplier companies and, accordingly, heating costs, depends on the type of building;

Architectural part. The dimensions of all kinds of external fences (walls, floors, roofs), the dimensions of openings (balconies, loggias, doors and windows) are taken into account. The number of storeys of the building, the presence of basements, attics and their features are important;
Temperature requirements for each room in the building. This parameter should be understood as temperature regimes for each room of a residential building or zone of an administrative building;
The design and features of external fences, including the type of materials, thickness, the presence of insulating layers;

Physical indicators of room cooling - data for calculating the heat load

The nature of the premises. As a rule, it is inherent in industrial buildings, where for a workshop or site it is necessary to create some specific thermal conditions and modes;
Availability and parameters of special premises. The presence of the same baths, pools and other similar structures;
The degree of maintenance - the presence of hot water supply, such as central heating, ventilation and air conditioning systems;
The total number of points from which hot water is drawn. It is on this characteristic that special attention should be paid, because what more number points - the greater the heat load on the entire heating system as a whole;
The number of people living in the home or in the facility. The requirements for humidity and temperature depend on this - factors that are included in the formula for calculating the heat load;

Equipment that can affect thermal loads

Other data. For an industrial facility, such factors include, for example, the number of shifts, the number of workers per shift, and working days per year.

As for a private house, you need to take into account the number of people living, the number of bathrooms, rooms, etc.

Calculation of heat loads: what is included in the process

Do-it-yourself calculation of the heating load itself is carried out even at the design stage of a country cottage or other real estate object - this is due to simplicity and the absence of extra cash costs. At the same time, the requirements of various norms and standards, TCP, SNB and GOST are taken into account.

The following factors are mandatory for determination during the calculation of thermal power:

Heat losses of external protections. Includes the desired temperature conditions in each of the rooms;
The power required to heat the water in the room;
The amount of heat required to heat the air ventilation (in the case when forced ventilation is required);
The heat needed to heat the water in the pool or bath;

Gcal/hour - a unit of measurement of thermal loads of objects

Possible developments of the further existence of the heating system. It implies the possibility of outputting heating to the attic, to the basement, as well as all kinds of buildings and extensions;

Heat loss in a standard residential building

Advice. With a "margin", thermal loads are calculated in order to exclude the possibility of unnecessary financial costs. This is especially true for a country house, where additional connection of heating elements without preliminary study and preparation will be prohibitively expensive.

Features of calculating the heat load

As already mentioned earlier, the design parameters of indoor air are selected from the relevant literature. At the same time, heat transfer coefficients are selected from the same sources (passport data of heating units are also taken into account).

The traditional calculation of heat loads for heating requires a consistent determination of the maximum heat flow from heating devices (all heating batteries actually located in the building), the maximum hourly heat energy consumption, as well as the total heat power consumption for a certain period, for example, the heating season.

Distribution of heat flows from various types of heaters

The above instructions for calculating thermal loads, taking into account the surface area of heat exchange, can be applied to various real estate objects. It should be noted that this method allows you to competently and most correctly develop a justification for using efficient heating as well as energy inspections of houses and buildings.

An ideal calculation method for the standby heating of an industrial facility, when temperatures are expected to drop during non-working hours (holidays and weekends are also taken into account).

Methods for determining thermal loads

Currently, thermal loads are calculated in several main ways:

Calculation of heat losses by means of enlarged indicators;
Determination of parameters through various elements of enclosing structures, additional losses for air heating;
Calculation of heat transfer of all heating and ventilation equipment installed in the building.

Enlarged method for calculating heating loads

Another method for calculating the loads on the heating system is the so-called enlarged method. As a rule, such a scheme is used in the case when there is no information about projects or such data does not correspond to the actual characteristics.

Examples of heat loads for residential apartment buildings and their dependence on the number of people living and area

For an enlarged calculation of the heat load of heating, a rather simple and uncomplicated formula is used:

Qmax from.=α*V*q0*(tv-tn.r.)*10-6

The following coefficients are used in the formula: α is a correction factor that takes into account the climatic conditions in the region where the building was built (applied when the design temperature is different from -30C); q0 specific heating characteristic, selected depending on the temperature of the coldest week of the year (the so-called "five days"); V is the outer volume of the building.

Types of thermal loads to be taken into account in the calculation

In the course of calculations (as well as when selecting equipment), a large number of various thermal loads are taken into account:

seasonal loads. As a rule, they have the following features:

Throughout the year, there is a change in thermal loads depending on the air temperature outside the premises;
Annual expenses heat, which are determined by the meteorological features of the region where the object for which the heat loads are calculated is located;

Thermal load regulator for boiler equipment

Changing the load on the heating system depending on the time of day. Due to the heat resistance of the building's external enclosures, such values are accepted as insignificant;
Heat energy consumption of the ventilation system by hours of the day.

Year-round thermal loads. It should be noted that for heating and hot water supply systems, most domestic facilities have heat consumption throughout the year, which changes quite a bit. So, for example, in summer the cost of thermal energy in comparison with winter is reduced by almost 30-35%;
Dry heat - convection heat transfer and thermal radiation from other similar devices. Determined by dry bulb temperature.

This factor depends on the mass of parameters, including all kinds of windows and doors, equipment, ventilation systems and even air exchange through cracks in the walls and ceilings. It also takes into account the number of people who can be in the room;

Latent heat is evaporation and condensation. Based on wet bulb temperature. The amount of latent heat of humidity and its sources in the room is determined.

Heat loss of a country house

In any room, humidity is affected by:

People and their number who are simultaneously in the room;
Technological and other equipment;
Air flows that pass through cracks and crevices in building structures.

Thermal load regulators as a way out of difficult situations

As you can see in many photos and videos of modern industrial and domestic heating boilers and other boiler equipment, they come with special heat load regulators. The technique of this category is designed to provide support for a certain level of loads, to exclude all kinds of jumps and dips.

It should be noted that RTN can significantly save on heating bills, because in many cases (and especially for industrial enterprises) certain limits are set that cannot be exceeded. Otherwise, if jumps and excesses of thermal loads are recorded, fines and similar sanctions are possible.

An example of the total heat load for a certain area of the city

Advice. Loads on heating, ventilation and air conditioning systems are an important point in designing a house. If it is impossible to carry out the design work on your own, then it is best to entrust it to specialists. At the same time, all formulas are simple and uncomplicated, and therefore it is not so difficult to calculate all the parameters by yourself.

Loads on ventilation and hot water supply - one of the factors of thermal systems

Thermal loads for heating, as a rule, are calculated in combination with ventilation. This is a seasonal load, it is designed to replace the exhaust air with clean air, as well as heat it up to the set temperature.

Hourly heat consumption for ventilation systems is calculated according to a certain formula:

Qv.=qv.V(tn.-tv.), where

Measurement of heat loss in a practical way

In addition to, in fact, ventilation, thermal loads are also calculated on the hot water supply system. The reasons for such calculations are similar to ventilation, and the formula is somewhat similar:

Qgvs.=0.042rv(tg.-tx.)Pgav, where

r, in, tg., tx. - design temperature of hot and cold water, water density, as well as a coefficient that takes into account the values of the maximum load of hot water supply to the average value established by GOST;

Comprehensive calculation of thermal loads

In addition to, in fact, theoretical issues of calculation, some practical work. So, for example, comprehensive thermal surveys include mandatory thermography of all structures - walls, ceilings, doors and windows. It should be noted that such works make it possible to determine and fix the factors that have a significant impact on the heat loss of the building.

Device for calculations and energy audit

Thermal imaging diagnostics will show what the real temperature difference will be when a certain strictly defined amount of heat passes through 1m2 of enclosing structures. Also, it will help to find out the heat consumption at a certain temperature difference.

Practical measurements are an indispensable component of various computational works. In combination, such processes will help to obtain the most reliable data on thermal loads and heat losses that will be observed in a particular building over a certain period of time. A practical calculation will help to achieve what the theory does not show, namely the "bottlenecks" of each structure.

Conclusion

The calculation of thermal loads, as well as the hydraulic calculation of the heating system, is an important factor, the calculations of which must be made before starting the organization of the heating system. If all the work is done correctly and the process is approached wisely, you can guarantee trouble-free operation of heating, as well as save money on overheating and other extra costs.

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Heating boilers

One of the main components of comfortable housing is the presence of a well-thought-out heating system. At the same time, the choice of the type of heating and the required equipment is one of the main questions that need to be answered at the design stage of the house. An objective calculation of the heating boiler power by area will eventually allow you to get a completely efficient heating system.

We will now tell you about the competent conduct of this work. In this case, we consider the features inherent in different types of heating. After all, they must be taken into account when carrying out calculations and the subsequent decision to install one or another type of heating.

Basic calculation rules

room area (S);
specific power of the heater per 10 m² of heated area - (W sp.). This value is determined adjusted for the climatic conditions of a particular region.

This value (W beats) is:

for the Moscow region - from 1.2 kW to 1.5 kW;
for the southern regions of the country - from 0.7 kW to 0.9 kW;
for the northern regions of the country - from 1.5 kW to 2.0 kW.

Let's do the calculations

The power calculation is carried out as follows:

W cat. \u003d (S * Wsp.): 10

Advice! For simplicity, a simplified version of this calculation can be used. In it Wud.=1. Therefore, the heat output of the boiler is defined as 10kW per 100m² of heated area. But with such calculations, at least 15% must be added to the obtained value in order to get a more objective figure.

Calculation example

As you can see, the instructions for calculating the heat transfer intensity are simple. But, nevertheless, we will accompany it with a concrete example.

The conditions will be as follows. The area of heated premises in the house is 100m². Specific power for the Moscow region is 1.2 kW. Substituting the available values into the formula, we get the following:

W boiler \u003d (100x1.2) / 10 \u003d 12 kilowatts.

Calculation for different types of heating boilers

The degree of efficiency of the heating system depends primarily on right choice her type. And of course, from the accuracy of the calculation of the required performance of the heating boiler. If the calculation of the thermal power of the heating system was not carried out accurately enough, then negative consequences will inevitably arise.

If the heat output of the boiler is less than required, it will be cold in the rooms in winter. In the case of excess performance, there will be an overexpenditure of energy and, accordingly, the money spent on heating the building.

House heating system

To avoid these and other problems, it is not enough just to know how to calculate the power of a heating boiler.

It is also necessary to take into account the features inherent in systems using different types of heaters (you can see a photo of each of them later in the text):

solid fuel;
electric;
liquid fuel;
gas.

The choice of one or another type largely depends on the region of residence and the level of infrastructure development. Equally important is the availability of the possibility of acquiring a certain type of fuel. And, of course, its cost.

Solid fuel boilers

The calculation of the power of a solid fuel boiler must be made taking into account the features characterized by the following features of such heaters:

low popularity;
relative accessibility;
the possibility of autonomous operation - it is provided for in a number of modern models of these devices;
economy during operation;
the need for additional fuel storage space.

solid fuel heater

Another characteristic feature that should be taken into account when calculating the heating power of a solid fuel boiler is the cyclicity of the temperature obtained. That is, in rooms heated with its help, the daily temperature will fluctuate within 5ºС.

Therefore, such a system is far from the best. And if possible, it should be abandoned. But, if this is not possible, there are two ways to smooth out the existing shortcomings:

Using a bulb, which is needed to adjust the air supply. This will increase the burning time and reduce the number of furnaces;
The use of water heat accumulators with a capacity of 2 to 10 m². They are included in the heating system, allowing you to reduce energy costs and, thereby, save fuel.

All this will reduce the required performance of a solid fuel boiler for heating a private house. Therefore, the effect of the application of these measures must be taken into account when calculating the power of the heating system.

Electric boilers

Electric boilers for home heating are characterized by the following features:

high cost of fuel - electricity;
possible problems due to network outages;
environmental friendliness;
ease of management;
compactness.

electric boiler

All these parameters should be taken into account when calculating the power of an electric heating boiler. After all, it is not purchased for one year.

Oil boilers

They have the following characteristic features:

not eco-friendly;
convenient in operation;
require additional storage space for fuel;
have an increased fire hazard;
use fuel, the price of which is quite high.

Oil heater

gas boilers

In most cases are the most the best option organization of the heating system. Domestic gas heating boilers have the following characteristic features, which must be taken into account when calculating the power of the heating boiler:

ease of operation;
do not require a place to store fuel;
safe in operation;
low cost of fuel;
economy.

A gas boiler

Calculation for heating radiators

Let's say you decide to install a heating radiator with your own hands. But first you need to buy it. And choose exactly the one that suits the power.

First, we determine the volume of the room. To do this, multiply the area of the room by its height. As a result, we get 42m³.
Further, you should know that it takes 41 watts to heat 1m³ of a room in central Russia. Therefore, to find out the desired performance of the radiator, we multiply this figure (41 W) by the volume of the room. As a result, we get 1722W.
Now let's calculate how many sections our radiator should have. Make it simple. Each element of a bimetallic or aluminum radiator has a heat transfer of 150W.
Therefore, we divide the performance we obtained (1722W) by 150. We get 11.48. Round up to 11.
Now you need to add another 15% to the resulting figure. This will help smooth out the increase in required heat transfer during the most severe winters. 15% of 11 is 1.68. Round up to 2.
As a result, we add 2 more to the existing figure (11). We get 13. So, to heat a room with an area of 14m², we need a radiator with a power of 1722W, which has 13 sections.

Now you know how to calculate the desired performance of the boiler, as well as the heating radiator. Take advantage of our advice and provide yourself with an efficient and at the same time not wasteful heating system. If you need more detailed information, then you can easily find it in the corresponding video on our website.

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All this equipment, indeed, requires a very respectful, prudent attitude - mistakes lead not only to financial losses, but to losses in health and attitude to life.

When we decide to build our own private house, we are primarily guided by largely emotional criteria - we want to have our own separate housing, independent of city utilities, much larger in size and made according to our own ideas. But somewhere in the soul, of course, there is an understanding that you will have to count a lot. The calculations relate not so much to the financial component of all work, but to the technical one. One of the most important types of calculations will be the calculation of the mandatory heating system, without which there is no escape.

First, of course, you need to take up the calculations - a calculator, a piece of paper and a pen will be the first tools

To begin with, decide what is called, in principle, about the methods of heating your home. After all, you have several options for providing heat at your disposal:

Autonomous heating electrical devices. It is possible that such devices are good, and even popular, as auxiliary means of heating, but they cannot be considered as the main ones.

Electric heating floors. But this method of heating may well be used as the main one for a single living room. But there is no question of providing all the rooms in the house with such floors.

Heating fireplaces. A brilliant option, it warms not only the air in the room, but also the soul, creates an unforgettable atmosphere of comfort. But then again, no one considers fireplaces as a means of providing heat throughout the house - only in the living room, only in the bedroom, and nothing more.

centralized water heating. Having “torn off” yourself from the high-rise building, you, nevertheless, can bring its “spirit” into your home by connecting to a centralized heating system. Is it worth it!? Is it worth it again to rush "out of the fire, but into the frying pan." This should not be done, even if such a possibility exists.

Autonomous water heating. But this method of providing heat is the most efficient, which can be called the main one for private houses.

You can not do without a detailed plan of the house with a layout of equipment and wiring of all communications

After resolving the issue in principle

When the solution to the fundamental question of how to provide heat in the house using an autonomous water system has taken place, you need to move on and understand that it will be incomplete if you do not think about

Installation of reliable window systems, which will not just “lower” all your successes in heating to the street;

Additional insulation of both external and internal walls Houses. The task is very important and requires a separate serious approach, although it is not directly related to the future installation of the heating system itself;

Fireplace installation. Recently, this auxiliary heating method has been increasingly used. It may not replace general heating, but it is such an excellent support for it that in any case it helps to significantly reduce heating costs.

The next step is to create a very accurate diagram of your building with all the elements of the heating system integrated into it. Calculation and installation of heating systems without such a scheme is impossible. The elements of this scheme will be:

Heating boiler, as the main element of the entire system;
A circulation pump that provides the coolant current in the system;
Pipelines, as a kind of "blood vessels" of the entire system;
Heating batteries are those devices that have long been known to everyone and which are the final elements of the system and are responsible in our eyes for the quality of its work;
Devices for monitoring the state of the system. An accurate calculation of the volume of the heating system is unthinkable without the presence of such devices that provide information about the actual temperature in the system and the volume of the passing coolant;
Locking and adjusting devices. Without these devices, the work will be incomplete, it is they who will allow you to regulate the operation of the system and adjust according to the readings of the control devices;
Various fitting systems. These systems could well be attributed to pipelines, but their influence on the successful operation of the entire system is so great that fittings and connectors are separated into a separate group of elements for the design and calculation of heating systems. Some experts call electronics the science of contacts. You can, without fear of making a big mistake, call the heating system - in many ways, the science of the quality of the compounds that provide the elements of this group.

The heart of the entire hot water heating system is the heating boiler. Modern boilers are entire systems for providing the entire system with hot coolant

Helpful advice! When it comes to the heating system, this word “coolant” often appears in the conversation. It is possible, with some degree of approximation, to consider ordinary “water” as the medium that is intended to move through the pipes and radiators of the heating system. But there are some nuances that are associated with the way water is supplied to the system. There are two ways - internal and external. External - from an external cold water supply. In this situation, indeed, the coolant will be ordinary water, with all its shortcomings. Firstly, in general availability, and, secondly, purity. When choosing this method of introducing water from the heating system, we highly recommend installing a filter at the inlet, otherwise severe contamination of the system cannot be avoided in just one season of operation. If a completely autonomous filling of water into the heating system is chosen, then do not forget to “flavor” it with all kinds of additives against solidification and corrosion. It is water with such additives that is already called a coolant.

Types of heating boilers

Among the heating boilers available for your choice are the following:

Solid fuel - can be very good in remote areas, in the mountains, in the Far North, where there are problems with external communications. But if access to such communications is not difficult, solid fuel boilers are not used, they lose in the convenience of working with them, if it is still necessary to keep one level of heat in the house;

Electric - and where now without electricity. But you need to understand that the cost of this type of energy in your house when using electric heating boilers will be so high that the solution to the question “how to calculate the heating system” in your house will lose any meaning - everything will go into electric wires;

Liquid fuel. Such boilers on gasoline, solarium, suggest themselves, but they, due to their non-environmental friendliness, are very unloved by many, and rightly so;

Domestic gas heating boilers are the most common types of boilers, very easy to operate and do not require a supply of fuel. The efficiency of such boilers is the highest of all available on the market and reaches 95%.

Pay special attention to the quality of all materials used, there is no time for savings, the quality of each component of the system, including pipes, must be perfect

Boiler calculation

When they talk about the calculation of an autonomous heating system, they first of all mean the calculation of the heating gas boiler. Any example of calculating the heating system includes the following formula for calculating the boiler power:

W \u003d S * Wsp / 10,

S is the total area of the heated room in square meters;
Wsp - specific power of the boiler per 10 sq.m. premises.

The specific power of the boiler is set depending on the climatic conditions of the region of its use:

for the Middle band, it ranges from 1.2 to 1.5 kW;
for areas of the level of Pskov and above - from 1.5 to 2.0 kW;
for Volgograd and below - from 0.7 - 0.9 kW.

But, after all, our climate of the XXI century has become so unpredictable that, by and large, the only criterion when choosing a boiler is your acquaintance with the experience of other heating systems. Perhaps, understanding this unpredictability, for simplicity, it has long been accepted in this formula to always take the specific power as a unit. Although do not forget about the recommended values.

Calculation and design of heating systems, to a large extent - the calculation of all junction points, the latest will help here connecting systems, of which there are many on the market.

Helpful advice! This desire is to get acquainted with existing, already working, systems autonomous heating will be very important. If you decide to establish such a system at home, and even with your own hands, then be sure to get acquainted with the heating methods used by your neighbors. Getting a "heating system calculation calculator" first hand will be very important. You will kill two birds with one stone - you will get a good adviser, and maybe in the future a good neighbor, and even a friend, and avoid mistakes that your neighbor may have made at one time.

Circulation pump

The method of supplying the coolant to the system largely depends on the heated area - natural or forced. Natural does not require any additional equipment and involves the movement of the coolant through the system due to the principles of gravity and heat transfer. Such a heating system can also be called passive.

Active heating systems, in which a circulation pump is used to move the coolant, are much more widespread. It is more common to install such pumps on the line from radiators to the boiler, when the water temperature has already subsided and cannot adversely affect the operation of the pump.

There are certain requirements for pumps:

they must be quiet, because they work constantly;
they should consume little, again due to their permanent job;
they must be very reliable, and this is the most important requirement for pumps in a heating system.

Piping and radiators

The most important component of the entire heating system, which any user constantly encounters, is pipes and radiators.

When it comes to pipes, we have three types of pipes at our disposal:

steel;
copper;
polymeric.

Steel - the patriarchs of heating systems, used from time immemorial. Now steel pipes are gradually disappearing "from the scene", they are inconvenient to use, and, in addition, require welding and are subject to corrosion.

Copper pipes are very popular, especially if hidden wiring is carried out. Such pipes are extremely resistant to external influences, but, unfortunately, are very expensive, which is the main brake on their widespread use.

Polymer - as a solution to the problems of copper pipes. It is polymer pipes that are the hit of use in modern systems heating. High reliability, resistance to external influences, a huge selection of additional auxiliary equipment specifically for use in heating systems with polymer pipes.

The heating of the house is largely ensured by the precise selection of the piping system and the laying of pipes.

Calculation of radiators

The thermotechnical calculation of the heating system necessarily includes the calculation of such an indispensable element of the network as a radiator.

The purpose of calculating the radiator is to obtain the number of its sections for heating a room of a given area.

Thus, the formula for calculating the number of sections in a radiator is:

K = S / (W / 100),

S - the area of the heated room in square meters (we heat, of course, not the area, but the volume, but the standard height of the room is 2.7 m);
W - heat transfer of one section in Watts, characteristic of the radiator;
K is the number of sections in the radiator.

Providing heat in the house is a solution to a whole range of tasks, often not related to each other, but serving the same purpose. Installing a fireplace can be one of these standalone tasks.

In addition to the calculation, radiators also require compliance with certain requirements during their installation:

installation must be carried out strictly under the windows, in the center, a long and generally accepted rule, but some manage to break it (such an installation prevents the movement of cold air from the window);
The "ribs" of the radiator must be aligned vertically - but this requirement, somehow no one particularly claims to violate it, is obvious;
something else is not obvious - if there are several radiators in the room, they should be located on the same level;
it is necessary to provide at least 5 cm gaps from the top to the window sill and from the bottom to the floor from the radiator, ease of maintenance plays an important role here.

Skillful and accurate placement of radiators ensures the success of the whole end result - here you can not do without diagrams and modeling of the location depending on the size of the radiators themselves

Calculation of water in the system

The calculation of the volume of water in the heating system depends on the following factors:

the volume of the heating boiler - this characteristic is known;
pump performance - this characteristic is also known, but it should, in any case, provide the recommended speed of movement of the coolant through the system of 1 m / s;
the volume of the entire pipeline system - this must already be calculated in fact, after the installation of the system;
the total volume of radiators.

The ideal, of course, is to hide all communications behind a plasterboard wall, but this is not always possible, and it raises questions from the point of view of the convenience of future maintenance of the system.

Helpful advice! Accurately calculate required volume water in the system is often not immediately possible with mathematical accuracy. So they act a little differently. First, the system is filled, presumably by 90% of the volume, and its performance is checked. As you work, vent excess air and continue filling. Hence, there is a need for an additional reservoir with a coolant in the system. As the system operates, a natural decrease in the coolant occurs as a result of evaporation and convection processes, therefore, the calculation of the replenishment of the heating system consists in monitoring the loss of water from the additional reservoir.

Definitely turn to the experts.

Many repair work Of course, you can also do housework by yourself. But creating a heating system requires too much knowledge and skills. Therefore, even having studied all the photo and video materials on our website, even having familiarized yourself with such indispensable attributes of each element of the system as an “instruction”, we still recommend that you contact professionals for installing a heating system.

As the top of the entire heating system - the creation of warm heated floors. But the feasibility of installing such floors should be very carefully calculated.

The cost of errors when installing an autonomous heating system is very high. It's not worth the risk in this situation. The only thing left for you is the smart maintenance of the entire system and the call of the masters for its maintenance.

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Competently made calculations of the heating system for any building - a residential building, workshop, office, shop, etc., will guarantee its stable, correct, reliable and silent operation. In addition, you will avoid misunderstandings with housing and communal services workers, unnecessary financial costs and energy losses. Heating can be calculated in several stages.

When calculating heating, many factors must be taken into account.

Calculation stages

First you need to know the heat loss of the building. This is necessary to determine the power of the boiler, as well as each of the radiators. Heat losses are calculated for each room with an external wall.

Note! The next step is to check the data. Divide the resulting numbers by the quadrature of the room. Thus, you will get specific heat losses (W/m²). As a rule, this is 50/150 W / m². If the received data is very different from those indicated, then you made a mistake. Therefore, the price of assembling the heating system will be too high.

Next, you need to choose the temperature regime. It is advisable to take the following parameters for calculations: 75-65-20 ° (boiler-radiators-room). Such a temperature regime, when calculating heat, complies with the European heating standard EN 442.

Heating scheme.

Then you need to select the power of the heating batteries, based on the data on heat losses in the rooms.
After that, a hydraulic calculation is carried out - heating without it will not be effective. It is needed to determine the diameter of the pipes and the technical properties of the circulation pump. If the house is private, then the pipe section can be selected according to the table, which will be given below.
Next, you need to decide on a heating boiler (domestic or industrial).
Then the volume of the heating system is found. You need to know its capacity in order to choose an expansion tank or make sure that the volume of the water tank already built into the heat generator is enough. Any online calculator will help you get the necessary data.

Thermal calculation

To carry out the heat engineering stage of designing a heating system, you will need initial data.

What you need to get started

House project.

First of all, you will need a building project. It should indicate the external and internal dimensions of each of the rooms, as well as windows and external doorways.
Next, find out the data on the location of the building in relation to the cardinal points, as well as the climatic conditions in your area.
Gather information about the height and composition of the outer walls.
You will also need to know the parameters of the floor materials (from the room to the ground), as well as the ceiling (from the premises to the street).

After collecting all the data, you can start calculating the heat consumption for heating. As a result of the work, you will collect information on the basis of which you can carry out hydraulic calculations.

Required formula

Building heat loss.

Calculation of thermal loads on the system should determine the heat losses and boiler output. In the latter case, the formula for calculating heating is as follows:

Mk = 1.2 ∙ Tp, where:

Mk is the power of the heat generator, in kW;
Tp - heat loss of the building;
1.2 is a margin equal to 20%.

Note! This safety factor takes into account the possibility of a pressure drop in the gas pipeline system in winter, in addition to unforeseen heat losses. For example, as the photo shows, due to a broken window, poor thermal insulation of doors, severe frosts. Such a margin allows you to widely regulate the temperature regime.

It should be noted that when the amount of thermal energy is calculated, its losses throughout the building are not evenly distributed, on average, the figures are as follows:

external walls lose about 40% of the total figure;
20% goes through the windows;
floors give about 10%;
10% escapes through the roof;
20% leave through ventilation and doors.

Material coefficients

Thermal conductivity coefficients of some materials.

K1 - type of windows;
K2 - thermal insulation of walls;
K3 - means the ratio of the area of \u200b\u200bwindows and floors;
K4 - the minimum temperature regime outside;
K5 - the number of external walls of the building;
K6 - number of storeys of the structure;
K7 - the height of the room.

As for windows, their heat loss coefficients are:

traditional glazing - 1.27;
double-glazed windows - 1;
three-chamber analogues - 0.85.

The larger the windows are relative to the floors, the more heat the building loses.

When calculating the consumption of thermal energy for heating, keep in mind that the material of the walls has the following coefficient values:

concrete blocks or panels - 1.25 / 1.5;
timber or logs - 1.25;
masonry in 1.5 bricks - 1.5;
masonry in 2.5 bricks - 1.1;
foam concrete blocks – 1.

At negative temperatures, heat leakage also increases.

Up to -10°, the coefficient will be equal to 0.7.
From -10° it will be 0.8.
At -15 °, you need to operate with a figure of 0.9.
Up to -20° - 1.
From -25° the value of the coefficient will be 1.1.
At -30° it will be 1.2.
Up to -35°, this value is 1.3.

When you calculate thermal energy, keep in mind that its loss also depends on how many external walls there are in the building:

one external wall - 1%;
2 walls - 1.2;
3 outer walls - 1.22;
4 walls - 1.33.

The greater the number of floors, the more difficult the calculations.

The number of floors or the type of premises located above the living room affect the coefficient K6. When the house has two floors or more, the calculation of heat energy for heating takes into account the coefficient 0.82. If at the same time the building has a warm attic, the figure changes to 0.91, if this room is not insulated, then to 1.

The height of the walls affects the level of the coefficient as follows:

2.5 m - 1;
3 m - 1.05;
3.5 m - 1.1;
4 m - 1.15;
4.5 m - 1.2.

Among other things, the method for calculating the need for thermal energy for heating takes into account the area of \u200b\u200bthe room - Pk, as well as the specific value of heat losses - UDtp.

The final formula for the necessary calculation of the heat loss coefficient looks like this:

Tp \u003d UDtp ∙ Pl ∙ K1 ∙ K2 ∙ K3 ∙ K4 ∙ K5 ∙ K6 ∙ K7. In this case, UDtp is 100 W/m².

Calculation example

The building for which we will find the load on the heating system will have the following parameters.

Windows with double glazing, i.e. K1 is 1.
External walls - foam concrete, the coefficient is the same. 3 of them are external, in other words K5 is 1.22.
The square of the windows is 23% of the same indicator of the floor - K3 is 1.1.
Outside temperature is -15°, K4 is 0.9.
The attic of the building is not insulated, in other words, K6 will be 1.
The height of the ceilings is three meters, i.е. K7 is 1.05.
The area of the premises is 135 m².

Knowing all the numbers, we substitute them into the formula:

Fri = 135 ∙ 100 ∙ 1 ∙ 1 ∙ 1.1 ∙ 0.9 ∙ 1.22 ∙ 1 ∙ 1.05 = 17120.565 W (17.1206 kW).

Mk = 1.2 ∙ 17.1206 = 20.54472 kW.

Hydraulic calculation for heating system

An example of a hydraulic calculation scheme.

This design stage will help you choose the right length and diameter of pipes, as well as correctly balance the heating system using radiator valves. This calculation will give you the opportunity to choose the power of the electric circulation pump.

High quality circulation pump.

According to the results of hydraulic calculations, you need to find out the following numbers:

M is the amount of water flow in the system (kg/s);
DP - head loss;
DP1, DP2… DPn, - head loss, from heat generator to each battery.

The flow rate of the coolant for the heating system is found by the formula:

M = Q/Cp ∙ DPt

Q means the total heating power, taken taking into account the heat losses of the house.
Cp is the specific heat capacity of water. To simplify the calculations, it can be taken as 4.19 kJ.
DPt is the temperature difference at the inlet and outlet of the boiler.

In the same way, it is possible to calculate the consumption of water (coolant) in any section of the pipeline. Select sections so that the fluid velocity is the same. According to the standard, division into sections must be carried out before reduction or tee. Next, sum up the power of all batteries to which water is supplied through each pipe interval. Then substitute the value in the above formula. These calculations must be made for the pipes in front of each of the batteries.

V is the speed of advancement of the coolant (m/s);
M - water consumption in the pipe section (kg / s);
P is its density (1 t/m³);
- F is the cross-sectional area of the pipes (m²), it is found by the formula: π ∙ r / 2, where the letter r means the inner diameter.

DPptr = R ∙ L,

R means specific friction loss in the pipe (Pa/m);
L is the length of the section (m);

After that, calculate the pressure loss on the resistances (fittings, fittings), the action formula:

Dms = Σξ ∙ V²/2 ∙ P

Σξ denotes the sum of the coefficients of local resistance in a given section;
V - water velocity in the system
P is the density of the coolant.

Note! In order for the circulation pump to sufficiently provide heat to all batteries, the pressure loss on the long branches of the system should not be more than 20,000 Pa. The coolant flow rate should be from 0.25 to 1.5 m/s.

If the speed is above the specified value, noise will appear in the system. The minimum speed value of 0.25 m / s is recommended by snip No. 2.04.05-91 so that the pipes do not air.

Pipes made of different materials have different properties.

In order to comply with all the voiced conditions, it is necessary to choose the right diameter of the pipes. You can do this according to the table below, which shows the total power of the batteries.

At the end of the article, you can watch a tutorial video on its topic.

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For installation, heating design standards must be observed

Numerous companies, as well as individuals, offer the population heating design with its subsequent installation. But do you really, if you are managing a construction site, do you definitely need a specialist in the field of calculation and installation of heating systems and appliances? The fact is that the price of such work is quite high, but with some effort, you can do it yourself.

How to heat your house

It is impossible to consider the installation and design of heating systems of all types in one article - it is better to pay attention to the most popular ones. Therefore, let's dwell on the calculations of the water radiator heating and some features of boilers for heating water circuits.

Calculation of the number of radiator sections and installation location

Sections can be added and removed by hand

Some Internet users have an obsessive desire to find SNiP for heating calculations in Russian Federation, but such settings simply do not exist. Such rules are possible for a very small region or country, but not for a country with the most diverse climate. The only thing that can be advised to lovers of printed standards is to refer to the tutorial on designing water heating systems for the universities of Zaitsev and Lyubarets.
The only standard that deserves attention is the amount of heat energy that should be released by a radiator per 1m2 of the room, with an average ceiling height of 270 cm (but not more than 300 cm). The heat transfer power should be 100W, therefore, the formula is suitable for calculations:

Knumber of sections \u003d S room area * 100 / P power of one section

For example, you can calculate how many sections you need for a room of 30m2 with a specific power of one section of 180W. In this case, K=S*100/P=30*100/180=16.66. Round this number up for the margin and get 17 sections.

Panel radiators

But what if the design and installation of heating systems is carried out by panel radiators, where it is impossible to add or remove part heater. In this case, it is necessary to select the battery power according to the cubic capacity of the heated room. Now we need to apply the formula:

P panel radiator power = V volume of heated room * 41 required amount of W per 1 cu.

Let's take a room of the same size with a height of 270 cm and get V=a*b*h=5*6*2?7=81m3. Let's substitute the initial data to the formula: P=V*41=81*41=3.321kW. But such radiators do not exist, so let's go up and get a device with a power reserve of 4 kW.

The radiator must be hung under the window

Whatever metal the radiators are made of, the rules for designing heating systems provide for their location under the window. The battery heats the air enveloping it, and as it heats up, it becomes lighter and rises. These warm streams create a natural barrier to cold streams moving from window panes, thus increasing the efficiency of the appliance.
Therefore, if you have calculated the number of sections or calculated the required radiator power, this does not mean at all that you can limit yourself to one device if there are several windows in the room (for some panel radiators, the instructions mention this). If the battery consists of sections, then they can be divided, leaving the same amount under each window, and you just need to purchase a few pieces of water for panel heaters, but of less power.

Boiler selection for the project

Covtion gas boiler Bosch Gaz 3000W

The terms of reference for the design of the heating system also include the choice of a domestic heating boiler, and if it runs on gas, then in addition to the difference in design power, it may turn out to be convection or condensing. The first system is quite simple - in this case, thermal energy arises only from gas combustion, but the second is more complex, because water vapor is also involved there, as a result of which fuel consumption is reduced by 25-30%.
You can also choose between open or closed chamber combustion. In the first situation, you need a chimney and natural ventilation - this is a cheaper way. The second case involves the forced supply of air into the chamber by a fan and the same removal of combustion products through a coaxial chimney.

gas boiler

If the design and installation of heating provides for a solid fuel boiler for heating a private house, then it is better to give preference to a gas generating device. The fact is that such systems are much more economical than conventional units, because the combustion of fuel in them occurs almost without a trace, and even that evaporates in the form of carbon dioxide and soot. When burning wood or coal from the lower chamber, the pyrolysis gas falls into another chamber, where it burns to the end, which justifies the very high efficiency.

Recommendations. There are other types of boilers, but about them now more briefly. So, if you opted for a liquid fuel heater, you can give preference to a unit with a multi-stage burner, thereby increasing the efficiency of the entire system.

Electrode boiler "Galan"

If you prefer electric boilers, then instead of a heating element it is better to purchase an electrode heater (see photo above). This is a relatively new invention in which the coolant itself serves as a conductor of electricity. But, nevertheless, it is completely safe and very economical.

Fireplace for heating a country house

Whether it is an industrial building or a residential building, you need to make competent calculations and draw up a diagram of the heating system circuit. At this stage, experts recommend paying special attention to the calculation of the possible heat load on the heating circuit, as well as the amount of fuel consumed and heat generated.

Thermal load: what is it?

This term refers to the amount of heat given off. The carried out preliminary calculation of the heat load will allow avoiding unnecessary costs for the purchase of components of the heating system and for their installation. Also, this calculation will help to correctly distribute the amount of heat generated economically and evenly throughout the building.

Main Factors

Purpose of the building: residential or industrial.

Characteristics of the structural elements of the structure. These are windows, walls, doors, roof and ventilation system.

The presence of rooms for special purposes (bath, sauna, etc.).

Degree of equipment with technical devices. That is, the presence of hot water supply, ventilation systems, air conditioning and the type of heating system.

For a single room. For example, in rooms intended for storage, it is not necessary to maintain a comfortable temperature for a person.

Number of points with hot water supply. The more of them, the more the system is loaded.

Area of glazed surfaces. Rooms with French windows lose a significant amount of heat.

Features of existing methods

The heat consumption, taken to the maximum for one hour of operation of the heating system,

The maximum heat flow from one radiator,

Total heat costs in a certain period (most often - a season); if an hourly calculation of the load on the heating network is required, then the calculation must be carried out taking into account the temperature difference during the day.

Basic calculation methods

To date, the calculation of the heat load on the heating of a building can be carried out in one of the following ways.

Three main

Aggregated indicators are taken for calculation.
The indicators of the structural elements of the building are taken as the base. Here, the calculation of the internal volume of air going to warm up will also be important.
All objects included in the heating system are calculated and summarized.

One exemplary

There is also a fourth option. It has a fairly large error, because the indicators are taken very average, or they are not enough. Here is the formula - Q from \u003d q 0 * a * V H * (t EH - t NPO), where:

q 0 - specific thermal characteristic of the building (most often determined by the coldest period),
a - correction factor (depends on the region and is taken from ready-made tables),
V H is the volume calculated from the outer planes.

Example of a simple calculation

For a building with standard parameters (ceiling heights, room sizes and good thermal insulation characteristics), a simple ratio of parameters can be applied, adjusted for a coefficient depending on the region.

Suppose that a residential building is located in the Arkhangelsk region, and its area is 170 square meters. m. The heat load will be equal to 17 * 1.6 \u003d 27.2 kW / h.

Such a definition of thermal loads does not take into account many important factors. For example, the design features of the structure, temperature, the number of walls, the ratio of the areas of walls and window openings, etc. Therefore, such calculations are not suitable for serious heating system projects.

It depends on the material from which they are made. Most often today, bimetallic, aluminum, steel are used, much less often cast-iron radiators. Each of them has its own heat transfer index (thermal power). Bimetallic radiators with a distance between the axes of 500 mm, on average, have 180 - 190 watts. Aluminum radiators have almost the same performance.

The calculation of the heating radiator by area includes the following basic parameters:

Ceiling height (standard - 2.7 m),

Thermal power (per sq. m - 100 W),

One outer wall.

These calculations show that for every 10 sq. m requires 1,000 W of thermal power. This result is divided by the heat output of one section. The answer is the required number of radiator sections.

For the southern regions of our country, as well as for the northern ones, decreasing and increasing coefficients have been developed.

Average calculation and exact

Given the factors described, the average calculation is carried out according to the following scheme. If for 1 sq. m requires 100 W of heat flow, then a room of 20 square meters. m should receive 2,000 watts. The radiator (popular bimetallic or aluminum) of eight sections allocates about Divide 2,000 by 150, we get 13 sections. But this is a rather enlarged calculation of the thermal load.

The exact one looks a little intimidating. Actually, nothing complicated. Here is the formula:

Q t \u003d 100 W / m 2 × S (rooms) m 2 × q 1 × q 2 × q 3 × q 4 × q 5 × q 6 × q 7, where:

q 1 - type of glazing (ordinary = 1.27, double = 1.0, triple = 0.85);
q 2 - wall insulation (weak or absent = 1.27, 2-brick wall = 1.0, modern, high = 0.85);
q 3 - the ratio of the total area of window openings to the floor area (40% = 1.2, 30% = 1.1, 20% - 0.9, 10% = 0.8);
q 4 - outdoor temperature (the minimum value is taken: -35 o C = 1.5, -25 o C = 1.3, -20 o C = 1.1, -15 o C = 0.9, -10 o C = 0.7);
q 5 - the number of external walls in the room (all four = 1.4, three = 1.3, corner room = 1.2, one = 1.2);
q 6 - type of calculation room above the calculation room (cold attic = 1.0, warm attic = 0.9, residential heated room = 0.8);
q 7 - ceiling height (4.5 m = 1.2, 4.0 m = 1.15, 3.5 m = 1.1, 3.0 m = 1.05, 2.5 m = 1.3).

Using any of the methods described, it is possible to calculate the heat load of an apartment building.

Approximate calculation

These are the conditions. The minimum temperature in the cold season is -20 ° C. Room 25 sq. m with triple glazing, double-leaf windows, ceiling height of 3.0 m, two-brick walls and an unheated attic. The calculation will be as follows:

Q \u003d 100 W / m 2 × 25 m 2 × 0.85 × 1 × 0.8 (12%) × 1.1 × 1.2 × 1 × 1.05.

The result, 2 356.20, is divided by 150. As a result, it turns out that 16 sections need to be installed in a room with the specified parameters.

If calculation is required in gigacalories

In the absence of a heat energy meter on an open heating circuit, the calculation of the heat load for heating the building is calculated by the formula Q \u003d V * (T 1 - T 2) / 1000, where:

V - the amount of water consumed by the heating system, calculated in tons or m 3,
T 1 - a number showing the temperature of hot water, measured in o C, and for calculations, the temperature corresponding to a certain pressure in the system is taken. This indicator has its own name - enthalpy. If it is not possible to remove temperature indicators in a practical way, they resort to an average indicator. It is in the range of 60-65 o C.
T 2 - temperature of cold water. It is quite difficult to measure it in the system, so constant indicators have been developed that depend on the temperature regime on the street. For example, in one of the regions, in the cold season, this indicator is taken equal to 5, in summer - 15.
1,000 is the coefficient for obtaining the result immediately in gigacalories.

In the case of a closed circuit, the heat load (gcal/h) is calculated differently:

Q from \u003d α * q o * V * (t in - t n.r.) * (1 + K n.r.) * 0.000001, where

The calculation of the heat load turns out to be somewhat enlarged, but it is this formula that is given in the technical literature.

Increasingly, in order to increase the efficiency of the heating system, they resort to buildings.

These works are carried out at night. For a more accurate result, you must observe the temperature difference between the room and the street: it must be at least 15 o. Fluorescent and incandescent lamps are switched off. It is advisable to remove carpets and furniture to the maximum, they knock down the device, giving some error.

The survey is carried out slowly, the data are recorded carefully. The scheme is simple.

The first stage of work takes place indoors. The device is moved gradually from doors to windows, paying special attention to corners and other joints.

The second stage is the examination of the external walls of the building with a thermal imager. The joints are still carefully examined, especially the connection with the roof.

The third stage is data processing. First, the device does this, then the readings are transferred to a computer, where the corresponding programs complete the processing and give the result.

The calculation of the heat load for heating a house was made according to the specific heat loss, the consumer approach to determining the reduced heat transfer coefficients - these are the main issues that we will consider in this post. Hello dear friends! We will calculate with you the heat load for heating the house (Qо.р) in various ways using enlarged meters. So what we know so far: 1. Estimated winter outdoor temperature for heating design tn = -40 °C. 2. Estimated (averaged) air temperature inside the heated house tv = +20 °C. 3. The volume of the house according to the external measurement V = 490.8 m3. 4. Heated area of the house Sot \u003d 151.7 m2 (residential - Szh \u003d 73.5 m2). 5. Degree day of the heating period GSOP = 6739.2 °C * day.

1. Calculation of the heat load for heating the house according to the heated area. Everything is simple here - it is assumed that the heat loss is 1 kW * hour per 10 m2 of the heated area of the house, with a ceiling height of up to 2.5 m. For our house, the calculated heat load for heating will be equal to Qо.р = Sot * wud = 151.7 * 0.1 = 15.17 kW. Determining the heat load in this way is not particularly accurate. The question is, where did this ratio come from and how does it correspond to our conditions. Here it is necessary to make a reservation that this ratio is valid for the Moscow region (tn = up to -30 ° C) and the house should be normally insulated. For other regions of Russia, specific heat losses wsp, kW/m2 are given in Table 1.

Table 1

What else should be taken into account when choosing the specific heat loss coefficient? Reputable design organizations require up to 20 additional data from the "Customer" and this is justified, since the correct calculation of heat loss by a house is one of the main factors determining how comfortable it will be in the room. Below are the typical requirements with explanations:
- the severity of the climatic zone - the lower the temperature "overboard", the more you have to heat. For comparison: at -10 degrees - 10 kW, and at -30 degrees - 15 kW;
– the condition of the windows – the tighter and more quantity glasses, the losses decrease. For example (at -10 degrees): standard double frame - 10 kW, double glazing - 8 kW, triple glazing- 7 kW;
- the ratio of the areas of windows and floor - than more window, the greater the losses. At 20% - 9 kW, at 30% - 11 kW, and at 50% - 14 kW;
– wall thickness or thermal insulation directly affect heat loss. So, with good thermal insulation and sufficient wall thickness (3 bricks - 800 mm), 10 kW is required, with 150 mm of insulation or a wall thickness of 2 bricks - 12 kW, and with poor insulation or a thickness of 1 brick - 15 kW;
- the number of external walls - is directly related to drafts and the multilateral effects of freezing. If the room has one outer wall, then 9 kW is required, and if - 4, then - 12 kW;
- the height of the ceiling, although not so significant, but still affects the increase in power consumption. At a standard height of 2.5 m, 9.3 kW is required, and at 5 m, 12 kW.
This explanation shows that a rough calculation of the required power of 1 kW of the boiler per 10 m2 of heated area is justified.

2. Calculation of the heat load for heating the house according to aggregated indicators in accordance with § 2.4 of SNiP N-36-73. To determine the heat load for heating in this way, we need to know the living area of the house. If it is not known, then it is accepted in the amount of 50% of total area Houses. Knowing the calculated outdoor air temperature for heating design, according to Table 2 we determine the aggregated indicator of the maximum hourly heat consumption per 1 m2 of living space.

table 2

For our house, the calculated heat load for heating will be equal to Qо.р = Szh * wsp.zh = 73.5 * 670 = 49245 kJ / h or 49245 / 4.19 = 11752 kcal / h or 11752/860 = 13.67 kW

3. Calculation of the heat load for heating the house according to the specific heating characteristic of the building.Determine heat load on this method we will be according to the specific thermal characteristic (specific heat loss of heat) and the volume of the house according to the formula:

Qo.r \u003d α * qo * V * (tv - tn) * 10-3, kW

Qо.р – estimated heat load on heating, kW;
α is a correction factor that takes into account the climatic conditions of the area and is used in cases where the calculated outdoor temperature tn differs from -30 ° C, is taken according to table 3;
qo – specific heating characteristic of the building, W/m3 * oC;
V is the volume of the heated part of the building according to the external measurement, m3;
tv is the design air temperature inside the heated building, °C;
tn is the calculated outdoor air temperature for heating design, °C.
In this formula, all quantities, except for the specific heating characteristic houses qo are known to us. The latter is a thermotechnical assessment of the construction part of the building and shows the heat flow required to increase the temperature of 1 m3 of the building volume by 1 °C. The numerical standard value of this characteristic, for residential buildings and hotels, is given in table 4.

Correction factor α

Table 3

tn	-10	-15	-20	-25	-30	-35	-40	-45	-50
α	1,45	1,29	1,17	1,08	1	0,95	0,9	0,85	0,82

Specific heating characteristic of the building, W/m3 * oC

Table 4

So, Qo.r \u003d α * qo * V * (tv - tn) * 10-3 \u003d 0.9 * 0.49 * 490.8 * (20 - (-40)) * 10-3 \u003d 12.99 kW. At the stage of the feasibility study of the construction (project), the specific heating characteristic should be one of the benchmarks. The thing is that in the reference literature, numerical value it is different, because it is given for different time periods, before 1958, after 1958, after 1975, etc. In addition, although not significantly, the climate on our planet has also changed. And we would like to know the value of the specific heating characteristic of the building today. Let's try to define it ourselves.

PROCEDURE FOR DETERMINING SPECIFIC HEATING CHARACTERISTICS

1. A prescriptive approach to the choice of heat transfer resistance of outdoor enclosures. In this case, the consumption of thermal energy is not controlled, and the values of heat transfer resistance of individual elements of the building must be at least standardized values, see Table 5. Here it is appropriate to give the Ermolaev formula for calculating the specific heating characteristics of the building. Here is the formula

qо = [Р/S * ((kс + φ * (kok – kс)) + 1/Н * (kpt + kpl)], W/m3 * оС

φ is the coefficient of glazing of the outer walls, we take φ = 0.25. This coefficient is taken as 25% of the floor area; P - the perimeter of the house, P = 40m; S - house area (10 * 10), S = 100 m2; H is the height of the building, H = 5m; ks, kok, kpt, kpl are the reduced heat transfer coefficients of the outer wall, skylights (windows), roof (ceiling), ceiling above the basement (floor), respectively. For the determination of the reduced heat transfer coefficients, both for the prescriptive approach and for the consumer approach, see tables 5,6,7,8. Well, with building dimensions we decided at home, but what about the building envelope of the house? What materials should the walls, ceiling, floor, windows and doors be made of? Dear friends, you must clearly understand that at this stage we should not be concerned about the choice of material for enclosing structures. The question is why? Yes, because in the above formula we will put the values of the normalized reduced heat transfer coefficients of enclosing structures. So, regardless of what material these structures will be made of and what their thickness is, the resistance must be certain. (Extract from SNiP II-3-79* Building heat engineering).

(prescriptive approach)

Table 5

(prescriptive approach)

Table 6

And only now, knowing GSOP = 6739.2 °C * day, by interpolation we determine the normalized resistance to heat transfer of enclosing structures, see table 5. The given heat transfer coefficients will be equal, respectively: kpr = 1 / Rо and are given in table 6. Specific heating characteristic at home qo \u003d \u003d [P / S * ((kc + φ * (kok - kc)) + 1 / H * (kpt + kpl)] \u003d \u003d 0.37 W / m3 * °C
The calculated heat load on heating with a prescriptive approach will be equal to Qо.р = α* qо * V * (tв - tн) * 10-3 = 0.9 * 0.37 * 490.8 * (20 - (-40)) * 10-3 = 9.81 kW

2. Consumer approach to the choice of resistance to heat transfer of external fences. In this case, the resistance to heat transfer of external fences can be reduced in comparison with the values \u200b\u200bindicated in Table 5, until the calculated specific heat energy consumption for heating the house exceeds the normalized one. The heat transfer resistance of individual fencing elements should not be lower than the minimum values: for the walls of a residential building Rc = 0.63Rо, for the floor and ceiling Rpl = 0.8Rо, Rpt = 0.8Rо, for windows Rok = 0.95Rо. The results of the calculation are shown in table 7. Table 8 shows the reduced heat transfer coefficients for the consumer approach. As for the specific consumption of thermal energy during the heating period, for our house this value is 120 kJ / m2 * oC * day. And it is determined according to SNiP 23-02-2003. We will determine this value when we calculate the heat load for heating in a more detailed way - taking into account the specific materials of the fences and their thermophysical properties (clause 5 of our plan for calculating the heating of a private house).

Rated resistance to heat transfer of enclosing structures
(consumer approach)

Table 7

Determination of the reduced heat transfer coefficients of enclosing structures
(consumer approach)

Table 8

Specific heating characteristic of the house qo \u003d \u003d [Р / S * ((kс + φ * (kok - kс)) + 1 / N * (kpt + kpl)] \u003d \u003d 0.447 W / m3 * ° C. Estimated heat load for heating at consumer approach will be equal to Qо.р = α * qо * V * (tв - tн) * 10-3 = 0.9 * 0.447 * 490.8 * (20 - (-40)) * 10-3 = 11.85 kW

Main conclusions:
1. Estimated heat load on heating for the heated area of the house, Qo.r = 15.17 kW.
2. Estimated heat load on heating according to aggregated indicators in accordance with § 2.4 of SNiP N-36-73. heated area of the house, Qo.r = 13.67 kW.
3. Estimated heat load for heating the house according to the normative specific heating characteristic of the building, Qo.r = 12.99 kW.
4. Calculated heat load for heating the house according to the prescriptive approach to the choice of heat transfer resistance of external fences, Qo.r = 9.81 kW.
5. Estimated heat load for home heating according to the consumer approach to the choice of heat transfer resistance of external fences, Qo.r = 11.85 kW.
As you can see, dear friends, the calculated heat load for heating a house with a different approach to its definition varies quite significantly - from 9.81 kW to 15.17 kW. What to choose and not to be mistaken? We will try to answer this question in the following posts. Today we have completed the 2nd point of our plan for the house. For those who haven't joined yet!

Sincerely, Grigory Volodin

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