Maximum water consumption for hot water. Examples of calculation of hot water systems

DHW calculations, BKN. We find the volume, DHW power, BKN (snake) power, warm-up time, etc.

In this article, we will consider practical problems for finding the volume of accumulation hot water, DHW heating capacity. The power of the heating equipment. Hot water availability time for various equipment and the like.

Consider examples of tasks:

Task 1. Find the capacity of instantaneous water heater

Instantaneous water heater- this is a water heater the volume of water in which it can be so small that its existence is useless for the accumulation of water. Therefore, it is considered that an instantaneous water heater is not intended to accumulate hot water. And we do not take this into account in the calculations.

Given: The water flow is 0.2 l/s. Temperature cold water 15 degrees Celsius.

To find: The power of an instantaneous water heater, provided that it heats the water up to 45 degrees.

Decision

Answer: The power of the instantaneous water heater will be 25120 W = 25 kW.

Practically not advisable to consume a large number of electricity. Therefore, it is necessary to accumulate (accumulate hot water) and reduce the load on the electrical wires.

Instantaneous water heaters have unstable heating of hot water. The hot water temperature will depend on the water flow through the instantaneous water heater. Switching power or temperature sensors do not allow for good temperature stabilization.

If you want to find the outlet temperature of an existing instantaneous water heater at a certain flow rate.

Task 2. Electric water heater (boiler) heating time

We have an electric water heater with a volume of 200 liters. The power of electric heating elements is 3 kW. It is necessary to find the time for heating water from 10 degrees to 90 degrees Celsius.

Given:

Wt \u003d 3kW \u003d 3000 W.

Find: The time it takes for the volume of water in the water heater tank to heat up from 10 to 90 degrees.

Decision

The power consumption of heating elements does not change from the temperature of the water in the tank. (How the power changes in heat exchangers will be considered in another problem.)

It is necessary to find the power of the heating elements, as for a flowing water heater. And this power will be enough to heat the water in 1 hour.

If it is known that with a heating element power of 18.6 kW the tank will heat water in 1 hour, then it is not difficult to calculate the time with a heating element power of 3 kW.

Answer: The time for heating water from 10 to 90 degrees with a capacity of 200 liters will be 6 hours 12 minutes.

Task 3. Boiler heating time indirect heating

Consider for example an indirect heating boiler: Buderus Logalux SU200

Rated power: 31.5 kW. It is not clear why this was found. But see the table below.

Volume 200 liters

The snake is made from steel pipe DN25. Inner diameter 25 mm. Outer 32 mm.

The hydraulic loss in the serpentine pipe indicates 190 mbar at a flow rate of 2 m3/h. Which corresponds to 4.6 .

Of course, this resistance is great for water and a new pipe. Most likely, risks were laid down for the overgrowth of the pipeline, for a coolant with high viscosity and resistance at the joints. It is better to specify big losses so that no one miscalculates.

Heat exchange area 0.9 m2.

Fits 6 liters of water in a serpentine pipe.

The length of this serpentine pipe is approximately 12 meters.

Warm-up time is 25 minutes. It is not clear how this was calculated. We look at the table.

BKN snake power table

Consider a table for determining the power of a snake

Consider SU200 snake heat dissipation power 32.8 kW

At the same time, the flow rate in the DHW circuit is 805 l / h. 10 degrees in, 45 degrees out

Another variant

Consider SU200 coil heat dissipation power 27.5 kW

A heat carrier with a temperature of 80 degrees flows into the snake with a flow rate of 2 m3 / hour.

At the same time, the flow rate in the DHW circuit is 475 l / h. 10 degrees in, 60 degrees out

Other characteristics

Unfortunately, I will not provide you with a calculation of the heating time for an indirect heating boiler. Because it's not just one formula. Here weave a lot of values: Starting from the heat transfer coefficient formulas, correction factors for different heat exchangers(since water convection also introduces its own deviations), and ends with an iteration of calculations for changed temperatures over time. Here, most likely in the future I will make a calculation calculator.

You will have to be content with what the manufacturer of the BKN (Indirect Heating Boiler) tells us.

And the manufacturer tells us the following:

That the water will be ready in 25 minutes. Provided that the flow into the snake will be 80 degrees with a flow rate of 2 m3 / hour. The power of the boiler, which gives the heated coolant, should not be lower than 31.5 kW. Ready-to-drink water is considered 45-60 degrees. 45 degrees wash in the shower. 60 is very hot water, for example for washing dishes.

Task 4. How much hot water do you need for a 30 minute shower?

Let's calculate for example with electric water heater. Since the electric heating element has a constant return of thermal energy. The power of heating elements is 3 kW.

Given:

Cold water 10 degrees

The minimum temperature from the tap is 45 degrees

The maximum water temperature in the tank is 80 degrees

Comfortable flow rate of flowing water from the tap 0.25 l/s.

Decision

First, we find the power that will provide a given water flow

Answer: 0.45 m3 = 450 liters of water will be needed in order to wash the accumulated hot water. Provided that the heaters do not heat the water at the time of consumption of hot water.

It may seem to many that there is no accounting for the entry of cold water into the tank. How to calculate the loss of thermal energy when a water temperature of 10 degrees falls into water of 80 degrees. Obviously there will be a loss of thermal energy.

It proves in the following way:

Energy spent on heating the tank from 10 to 80:

That is, a 450-liter tank with a temperature of 80 degrees already contains 36 kW of thermal energy.

We take energy from this tank: 450 liters of water with a temperature of 45 degrees (through a tap). Thermal energy of water with a volume of 450 liters at a temperature of 45 degrees = 18 kW.

This is proven by the law of conservation of energy. Initially, there were 36 kW of energy in the tank, 18 kW were taken away, 18 kW remained. These 18 kW of energy contain water with a temperature of 45 degrees. That is, 70 degrees divided in half got 35 degrees. 35 degrees + 10 degrees of cold water, we get a temperature of 45 degrees.

The main thing here is to understand what the law of conservation of energy is. This energy from the tank cannot escape to no one knows where! We know that 18 kW came out through the tap, and 36 kW was originally in the tank. Taking 18 kW from the tank, we will lower the temperature in the tank to 45 degrees (to an average temperature of (80 + 10) / 2 = 45).

Let's now try to find the volume of the tank when the boiler is heated to 90 degrees.

Used energy consumption of hot water at the outlet of the tap 18317 W

Answer: The volume of the tank is 350 liters. An increase of just 10 degrees reduced the volume of the tank by 100 liters.

To many, this may seem unrealistic. This can be explained as follows: 100/450 = 0.22 is not that much. Stored temperature difference (80-45)

We prove that this is a fair formula in another way:

Of course, this is a rough theoretical calculation! In the theoretical calculation, we take into account the fact that the temperature in the tank between the upper and lower layers instantly mixes. If we take into account the fact that the water is hotter at the top and colder at the bottom, then the volume of the tank can be reduced by the temperature difference. No wonder vertical tanks are considered more efficient in terms of thermal energy conservation. Since the greater the height of the tank, the higher the temperature difference between the upper and lower layers. With rapid consumption of hot water, this temperature difference is higher. When there is no water flow, very slowly the temperature in the tank becomes uniform.

We'll just drop 45 degrees 10 degrees lower. For place 45 will be 35 degrees.

Answer: Due to the temperature shift, we reduced the volume of the tank by another 0.35-0.286=64 liters.

We calculated on the condition that at the time of consumption of hot water, the heaters did not work and did not heat the water.

Let's now calculate under the condition that the tank starts to heat the water at the moment the hot water is consumed.

Let's add another power of 3 kW.

For 30 minutes of work, we will get half the power of 1.5 kW.

Then you need to subtract this power.

Answer: The volume of the tank will be 410 liters.

Task 5. Calculation of additional capacity for domestic hot water

Consider private house area of ​​200 m2. The maximum power consumption for home heating is 15 kW.

4 people live in the house.

To find: Additional capacity for domestic hot water

That is, we need to find the power of the boiler, taking into account: House heating power + hot water heating.

For this purpose, it is better to use scheme number 4:

Decision

It is necessary to find how many liters of hot water a person consumes per day:

SNiP 2.04.01-85 * states that according to statistics, 300 liters per person per day are consumed. Of these, 120 liters for hot water with a temperature of 60 degrees. These are urban statistics mixed with people who are not used to spending so much water per day. I can offer my consumption statistics: If you like to take hot baths every day, you can spend 300-500 liters of hot water per day for only one person.

The volume of water per day for 4 people:

That is, it is necessary to add 930 W. = 15930 W to the house heating power of 15 kW.

But if you take into account the fact that at night (from 23:00 - 7:00) you do not consume hot water, then you get 16 hours when you consume hot water:

Answer: Boiler power = 15 kW + 1.4 kW for DHW. = 16.4 kW.

But in this calculation there is a risk that at the time of high consumption of hot water at certain hours you will stop heating the house for a long time.

If you want to have good expense hot water for a private house, then we choose a BKN of at least 30 kW. This will allow you to have an unlimited flow rate of 0.22 l/s. with a temperature of at least 45 degrees. The boiler power should not be less than 30 kW.

In general, in the tasks of this article there was a bias towards energy conservation. We did not consider what is happening at a particular moment, but went for the calculation in a different way. We went for the indisputable method of conservation of energy. The energy expended at the outlet of the tap will then be equal to the energy coming from the boiler equipment. Knowing the powers in two different places you can find the time spent.

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The main parameters of residential buildings are water supply, sewerage system and supply electrical energy. Regardless of the number of residents (a private house or a multi-storey building), the calculation of the main networks must be carried out in accordance with certain rules, using the appropriate formulas. It does not take much time to create the correct electrical circuit, it is much harder to decide on the water supply. Of particular difficulty is the design and calculation of hot water supply. To correctly perform all operations, you need to know not only technical side issue, but also the regulatory framework.

The most commonly chosen type of circulation networks. The principle of operation of such a system is the constant circulation of the liquid. The only downside circulation system hot water is too high price. The costs are justified only when the maximum number of users for a residential building is reached.

Also, in addition to the high pricing policy, the constant circulation of water leads to significant heat losses, which entails additional costs. In the presence of a circulation system, designers try to minimize the length of the pipeline. This option allows you to create additional savings on the transportation of liquid.

What is a waiting period and how is it calculated?

The waiting period is the time period that elapses from the time the tap is opened by the user until the hot water is supplied. They try to reduce this time as much as possible, for this they optimize the hot water supply system, make adjustments, and if the performance is poor, they upgrade it.

To set the waiting period, generally accepted norms are used. To calculate it correctly, you need to know the following:

• To reduce the waiting period, you should create a high water pressure in the system. But setting too high pressure parameters can damage the pipeline.
• To reduce the waiting period, increase throughput device through which the user receives liquid.
• The waiting period increases in direct proportion to the internal diameter of the pipeline, and also if there is a circuit at a great distance from the consumer.

The correct sequence for calculating the waiting period is:

• Determining the number of consumers. After the exact figure, you should make a small margin, as there are peak hot water costs.
• Determining the characteristics of the pipeline: length, internal diameter of the pipes, as well as the material from which they are made.
• Multiplying the length of the pipeline and its internal diameter by the specific volume of water, which is measured in l / s.
• Determining the shortest and most convenient fluid path. This parameter also includes the sections of the contour located the farthest from the water tap. All volumes of water are also added.
• The amount of liquid is divided by the flow of water carried out in one second. When obtaining this parameter, the total fluid pressure in the system is also taken into account.

To achieve the most accurate results, you should correctly calculate the specific volume of the pipeline. For this, the following formula is applied:

Cs = 10 (F/100)2 3.14/4 where F is the inside diameter of the pipeline.

When determining the specific volume, you cannot use the value of both the external and nominal diameters of pipes. This will significantly reduce the accuracy of the calculations. There are tables in which the value of the specific volume is pre-calculated for certain materials (copper and steel).

Calculation of hot water consumption per day

The amount of hot water that the user needs for a day is a parameter calculated in advance. Typically, such data is taken from tables, where they are divided according to the type of room and its quadrature. European parameters should not be confused with other countries, they are strikingly different from each other.

On average, the consumption of hot water per person per day is from 25 to 50 liters. Compiling and calculating the amount of hot water per person is possible only after the status of the room or building is known.

How to calculate the pipeline

For long-term operation of a hot liquid transportation system, it is necessary to calculate the pipeline under peak load conditions. This allows you to make a certain margin, which will eliminate the occurrence of malfunctions in the system with a sharp increase in pressure.

For the calculation of the pipeline, most often, ready-made diagrams and tables with relevant data are used. The material most often taken is copper or galvanized steel. You should be aware that an important calculation parameter is the equivalent Fixture Unit. This device is called a conditional element for a certain type of water folding mechanisms.

Pipeline calculation sequence:

• The calculation begins with the determination of the Fixture Unit parameter, which is mandatory for each draw point.
• The main hot water transportation network is divided into separate sections(nodes). The principle is based on the design of the heating system.
• Find the total number of Fixture Units that will be located on the various sites.
• Based on the total amount of the Fixture Unit and the type of building, find the estimated flow rate for each section of the system.
• Design flow, also referred to as throughput, is an important consideration in determining the diameter of a pipeline. The inner diameter of the pipes is determined with the condition that the final figures will not exceed the generally established limits.

When calculating the circulation network, you can use the general position that there are 3 l / s for each element of the Fixture Unit. A separate item is the calculation of the recirculation pump, which has a certain throughput. To determine this parameter, it is necessary to know the exact number of water points.

To provide the circulation network with additional savings, a thermostat is installed on the pump. The thermostat ensures that the device turns on when the temperature of the transported liquid drops. When the water temperature on the return circuit reaches a value less than the nominal value by 5 degrees, the pump turns off.

What you need to have to start calculating hot water supply

It is impossible to start calculating the hot water supply system without having technical and design documentation for the house. At the same time, the size of the house is not important; for a private plot, the same plan is required as for a multi-storey building.

The calculation begins with a certified architectural plan, on which correct location buildings, as well as the placement of sanitary appliances. The location of the house will help you choose the supply of the water supply system along the shortest path.

You need to know the number of people who will live in the building. It is natural that the exact number of residents cannot be found out, so it is better to calculate according to the maximum data. These figures will allow us to calculate right time peak loads.

Determine the place where the hot water supply equipment will be placed. This section must be indicated on the diagram without fail.

Hot water supply is called the supply of water from elevated temperature through a centralized pipeline and internal engineering structures to private and multi-apartment buildings (including non-residential premises and premises of joint ownership). This article is devoted to the calculation of hot water supply.

In this article you will learn:

• How is the calculation of hot water.
• What formula is used to calculate the standard for hot water supply.
• How to recalculate hot water supply for general house needs.
• Why control the quality of hot water.

Calculation of the hot water supply system

The calculation of the hot water supply system is based on the calculation of heat for this type of water supply. The fact is that the average temperature of cold water is 10 ° C, but at the outlet this figure is much lower, which creates discomfort when using water for the consumer from the mixer (60 ° C). Based on this, when calculating the temperature, it is recommended to increase it to 50 ° C.

The algorithm for calculating the average heat consumption for hot water extraction looks like this:

qm = m* t* c *∆t, kW*h,

where m is water consumption, l/h; t is the operating time, h; ∆t is the temperature difference; c is the specific heat capacity, kW x h/(l x °C).

Calculation of the standard for hot water supply

The rate of water supply (cubic meters per month for 1 person) is determined as follows:

N = Sum (Q x n) x (4.5 + 0.07 + L) x 10 where

Q - water consumption by 1 water-folding mechanism for 1 operation; n - the number of operations for using 1 water-folding device for i - 7 days; L is the number of floors in an apartment building or residential building.

Consumption rates and average water temperature per operation

The indicator of hot water supply (cubic meters per month per 1 person) is calculated as follows:

Calculation of payment for hot water supply: 2 options

Calculation No. 1 - Calculation in the residential area, a hot water consumption meter is installed.

If an individual metering device for hot water supply is installed in the apartment, the calculation of the amount of payment for hot water supply will be made according to formula No. 1, as the product of the amount of hot water consumed in the apartment according to indications individual device accounting and tariff for hot water supply established for the region and service provider:

Formula #1

P i \u003d V i p x T cr

V i p - volume(quantity) of hot water supply consumed during the billing period in a residential or non-residential premises, determined according to the readings of an individual or general (apartment) meter;

T kr - tariff(price) for hot water supply, established in accordance with the legislation Russian Federation.

DHW calculation example

Based on meter readings, in January 2017. 4 m3 of hot water was used.

The cost of 1 m3 of hot water in this region, taking into account the services of an intermediary, is 90 rubles. 00 kop.

Having such data, it is possible to calculate hot water supply for this particular case:

4 x 90.00 = RUB 360.00

Calculation No. 2 - a hot water consumption meter is not installed in the living room.

For such cases, formula No. 4 is used, which takes into account data on hot water consumption rates in the region, the number of people living in the apartment and the cost of hot water supply, taking into account the region and supplier.

Formula #4

P i = n i x N j x T cr

• the number of citizens permanently and/or temporarily residing in the apartment;
• the norm established for hot water supply for the region;
• tariff set for hot water supply for the region and service provider.

DHW calculation example

If we take as a basis that three people live in the room, the rate of hot water consumption in this region is 3.5 m 3 / person, and the tariff for hot water supply is 90 rubles. 00 kop. for 1 m 3, then you can calculate the amount of payment for using hot water in a given living space as follows:

3 x 3.5 x 90.00 = 945.00 rubles.

Calculation of hot water supply for general house needs

May 06, 2011 The Government of the Russian Federation signed Decree No. 354 on a new procedure for calculating the amount of payment for utilities. According to this document, apartment residents must pay not only for hot water consumed by them at home, but also for hot water supply, which serves general house needs. These changes caused dissatisfaction among citizens and, first of all, because it was not clear what kind of surpluses water is coming speech and what it is spent on in such significant volumes.

Below is the calculation of payment for hot water supply for general house purposes.

• Calculation No. 1 - calculation of the DHW of a house on which a hot water consumption meter is not installed.

The calculation of the amount to pay for the consumed hot water for general house purposes is carried out according to the formulas No. 10, 15, which allow you to determine the amount of hot water consumed and the amount of the required payment, respectively.

Formula #10

P i one \u003d V i one x T cr

• V i od- the amount of hot water that was used for general house purposes in an apartment building and falls on a residential or non-residential premises for the billing period;
• T cr- the cost of hot water supply according to the laws of the Russian Federation.

Formula #15

V i one.5 \u003d N one x S o and x (S i / S about)

• N one- the rate of consumption of hot water supplied for the billing period and spent for general house purposes in an apartment building;
• Si- the total area of ​​residential and non-residential premises in an apartment building;
• S about- the total area of ​​all residential and non-residential premises in an apartment building;
• S oi- the total area of ​​common premises in an apartment building.

Calculation Sample

The rate of hot water consumption for general house purposes in the region is 0.3 m 3 per 1 m 2. The total area of ​​​​premises under common house management is 400 m 2. The total area of ​​all residential premises of a given apartment building equal to 4,000 m 2. total area one apartment - 45 m 2. In this region, payment for hot water is set at 90 rubles. 00 kop. for 1 m 3. Using these data, we get the following calculations:

0.3 x 400 x 45 / 4000 = 1.35 cubic meters 1.35 x 90 = 121.50 rubles

• Calculation No. 2 - calculation of the DHW of a house on which a hot water consumption meter is installed

To calculate the payment for the consumption of hot water, formulas No. 10, 12 are used, which allow you to determine the volume of hot water and the amount of payment, respectively.

Formula #12

Calculation Sample

The amount of hot water that was consumed according to the common house meter is 2,000 m 3. The amount of hot water consumed in all residential premises according to indications individual counters, equal to 1 200 m 3. The amount of hot water consumed in those apartments where there are no individual meters is 500 m 3. The total area of ​​apartments in the house is 4,000 m2. The area of ​​one apartment is 45 m 2.

The cost of 1 m 3 of hot water in the region under consideration, taking into account the interests of the service provider, is 90 rubles. 00 kop.

Based on the above data, the calculation of payment for hot water supply for general house purposes is as follows:

(2,000 - 1,200 - 500) x 45/4000 = 3.375 cubic meters 3.375 x 90.00 = 303.75 rubles

Summarizing the presented examples of calculations, it should be said that in the absence of a collective meter, the volume of hot water for common house needs will be determined by the area of ​​\u200b\u200bpremises in common house ownership and the tariff for hot water supply.

It is important to know that if extra cubic meters of hot water are found, a common house meter will allow you to understand the causes of this phenomenon. If there is no such meter, then it is not possible to find the cause of the surplus and influence the amount of payment for the general house consumption of hot water.

Calculation of the load of hot water supply

The calculation of the load of hot water supply is required to be made when:

• reduction of calculated thermal loads;
• reduction of heating costs;
• coordination of changes in the composition of heat-consuming installations (change in the number of heaters or disassembly of the ventilation system). This happens if the type of ventilation is changed in the room or a thermal curtain is installed;
• the need to confirm that the new heat load and heat consumption are in line with the design norms;
• planning your own heating system;
• planning individual node heat supply;
• if necessary, correct distribution of heat load between sub-subscribers;
• connection to the common heating main of new facilities (single and/or complex structures);
• signing a new contract with a heat supplier;
• the need to specify thermal loads in non-residential premises for individual institutions;
• repayment by organizations of the cost of services by calculation (in cases where it is impossible to install a meter);
• unreasonable increase in the consumption of heat energy by the supplier or management company.

As for the rights of consumers in the field of calculating thermal energy for hot water supply, they are fixed:

• in all standard contracts concluded regarding the supply of heat and energy resources;
• in the order of the Ministry of Regional Development of the Russian Federation dated December 28, 2009 No. No. 610 “On approval of the rules for establishing and changing (revising) thermal loads”.

According to this document, the re-consideration of contractual indicators should be preceded by the creation of a technical report, which will reflect the calculation of heat loads, as well as arguments for the need to adjust or reduce the heat load on a particular object.

In addition, the order of the Ministry of Regional Development of the Russian Federation of December 28, 2009 No. No. 610 allows adjustments to be made to the calculation of heat for hot water supply, heating and ventilation in the following cases:

• during the overhaul;
• when restoring internal engineering structures aimed at reducing waste of energy resources;
• when strengthening the thermal insulation of a particular object;
• when carrying out other procedures aimed at saving energy resources.

Before starting the review of thermal loads for buildings in operation and connecting new objects to the general system, it is required:

• collect all available information about the object;
• implement audit the power system of the facility;
• to carry out the calculation of thermal loads for hot water supply, heating and ventilation based on the results of the check;
• write a technical report;
• discuss the report with the supplier of heat and power resources;
• make adjustments to the existing one or sign a new contract with the energy supplier company.

Hydraulic calculation of hot water supply

The main goal of the hydraulic calculation of hot water supply is the calculation of the dimensions (in particular, the diameter) of the pipes through which water is supplied, and the costs of pressure. The starting value for the implementation of such calculations is considered to be the second flow rate, taking into account the value of the residual circulation:

qh, сir = qh (1 + kсir), l/s,

in this case, kсir is the residual circulation index.

To calculate this parameter, it is required to divide the second flow by the circulation inside the hot water supply system. The formula will look like this:

kсir = f(qh/qсir).

In this situation, the conditions are such that kсir ≠ 0 only in the very first parts of the pipeline, despite the fact that qh/qсir is greater than two. In all other cases kсir will be equal to 0. An important point is that the hydraulic calculation is made before the circulation calculation. This fact implies that the specialist is forced to put forward a hypothesis about the parameters of the qh / qсir ratio (for residential buildings, qh / qсir is usually greater than 2.0) and argue it.

The calculation of the size of the cost of pressure in the water risers, united by an annular jumper into sectional nodes, is made on the basis of the estimated water flow with an index of 0.7. For the estimated flow rate in the annular sections, it is customary to take the highest second flow rate for one of the devices that is subject to maintenance as the lowest threshold.

As for the speed of movement of water in the hot water pipeline, it should not exceed three meters per second. But at the same time, it has been proven that the speed of water, exceeding one and a half meters per second, is the cause of noise.

In order to calculate the diameter of the riser when the resistance does not match, it is customary to take the estimated flow and pressure at the very base of the riser as a basis. If the resistance indicators are identical, the diameter of the extreme riser is taken as a single value.

To carry out a competent hydraulic calculation of any direction, it is required to have an idea about the basic laws of hydrodynamics (among other things, the Darcy-Weisbach equation). But you need to be prepared that each area will impose its own specifics on the implementation of the hydraulic calculation (for example, the calculation in the field of hot water supply is very typical, which eliminates the need to calculate the pressure costs separately).

There is an algorithm for calculating pressure losses in sections of the hot water supply system:

Н = i×l(1 + kl), mm,

where i - specific linear head loss, mm/m; l is the length of the section; kl is an index that takes into account pressure losses in local resistances.

Indicators i are taken from the relevant directories.

Do not forget that there are cases when hard water from the pipeline is heated for hot water supply. This situation is fraught with the appearance of growths inside the pipes (the so-called hardness salts). In this situation, a nomogram is used to calculate the index i.

• Available and required pressure in DHW systems in the drawdown mode

The pressure guaranteed at the inlet and used, if necessary, to supply water for the purposes of hot water supply is called available. Another type of pressure - required, is characterized by the fact that it serves to pass the resistance of the hydraulics when water is supplied to the most remote (remotely and in height) device.

If we take a closed hot water supply system as an example, then the available pressure will be the pressure of the cold water supply at the junction with the hot pipeline. And to calculate the required pressure, the following formula is used:

Nreb \u003d Npod + Nsch + Nvn + Ng + Nsv,

where Нpod - pressure loss in the supply pipelines in the drawdown mode; Нсч - pressure loss in the water meter (water meter); Hvp - pressure loss in the water heater; Hg - the difference between the geodetic indicators of the highest located device and the junction of the hot water supply system with cold water supply; Hsv - free pressure on the device ("on the spout").

For an open system for the supply of heat resources, which involves analysis directly from the heating main, the pressure in the return water supply of the heating main at the hot water supply system connection point will be available. The calculation of the required pressure (in the absence of a water heater) will be carried out as follows:

Nreb \u003d Npod + Nsch + Ng + Hsv,

where Hg is determined from the specific place of connection to the heating main. In hot water supply systems operating on the principle of gravity under the influence of the water column in accumulating vessels, the available pressure is taken directly from the geodetic difference between the indicators of the water level in such a vessel and the device located as high as possible. The calculation of the required pressure for this situation looks like this:

Nreb \u003d Npod + Hsv

Recalculation and calculation of hot water supply

Article 542 of the Civil Code of the Russian Federation establishes that the quality of the energy resources provided must meet the criteria fixed by the law of the Russian Federation, as well as the clauses of the contract for the supply of energy resources. Article 538 of the Civil Code of the Russian Federation prescribes that the above rules be applied to relations arising from the supply of energy resources, since no other procedure is provided for by law.

The temperature of hot water in the water intake units is regulated by clause 2.4 of SanPiN 2.1.4.2496-09 " Hygiene requirements to ensuring the safety of hot water supply systems”, approved by the Decree of the Chief State Sanitary Doctor of the Russian Federation dated April 07, 2009 No. No. 20. According to this document, t at the outlet should not go beyond 60 - 75 °C. The prescriptions of SanPin must be strictly observed by those legal entities who, by occupation, are associated with the implementation and establishment of the work of the hot water supply line.

Subparagraph “B” of paragraph 17 of the Rules for Concluding Contracts for the Supply of Energy Resources indicates the importance in this area of ​​such an indicator as the quality of the resources provided, which should ensure the maintenance of common house property at the proper level. Public services must be provided to citizens in full compliance with the Rules for the provision of public services and the terms of connection apartment buildings and uniting them common networks engineering and technical support to centralized networks engineering and technical support (clause 20 of the Rules for Concluding Contracts for the Supply of Energy Resources).

According to clause 5, annex 1 to the Rules for the provision of public services, the quality of public services in the field of hot water supply must meet the following criteria: ensure compliance temperature regime in the water intake unit in accordance with the law of the Russian Federation on technical regulation and the provisions of SanPin.

The responsibilities of the repair and construction organization, which is responsible for the supply of water, include ensuring its quality and the desired temperature (in the range from 60 to 75 ° C), although the law of the Russian Federation does not give strict instructions on this issue. The supplier company is responsible for ensuring that the coolant reaches the citizens in the proper quality. If the water temperature indicator turns out to be less than the lower limit established by the regulations (Resolution of the AS WSO dated October 12, 2015 No. F04-24751 / 2015 in case No. A45-19993 / 2014), citizens have the right to file a claim with the court, which will oblige the defendant (company - energy supplier) to correct the violations.

Clause 5, annex 1 to the Rules for the provision of public services allows you to allow deviations from the temperature indicators established by law. So, the deviation from the accepted temperature at night from 00 h. 00 min. until 05:00 can be 5°C; in the afternoon from 05 h. 00 min. until 00 h. 00 min. - 3°C. Despite the existence of such reservations, such a provision is not considered the norm. Decision of the Supreme Court of the Russian Federation of May 31, 2013 No. No. AKPI13-394 states that such deviations are indicators of the provision of services of inadequate quality.

In order for the hot water temperature to be 60 ° C at the water intake points, it must be an order of magnitude higher at the entrance to the house. However, as already mentioned, there are no legislative regulations regarding this particular indicator, therefore, in the case of going to court, we can only talk about the fact that the repair and construction company must ensure that the water temperature at the entrance to the house is not less than 60 ° C.

When can the MKD manager apply for the recalculation of the cost of hot water

Paragraph 2 of Article 542 of the Civil Code of the Russian Federation gives citizens the right to refuse to pay for energy resources of inappropriate quality. But the supplier company is also allowed to demand from citizens in this case compensation for energy losses.

There are also legislative regulations regarding changing the procedure for paying for consumed energy resources if they were of inadequate quality or were supplied with interruptions exceeding the allowable period (subparagraph “e” of paragraph 22 of the Rules for Concluding Resource Supply Contracts). Regulate the procedure for recalculating payment Rules for the provision of utility services.

The current legislation of the Russian Federation recognizes the unconditional advantage of the system for monitoring consumed resources by installing meters in the border area between the area of ​​responsibility of the supplier company and the property of citizens. If a meter is installed on the house and there were no complaints about its operation, then the indicators of this device can be considered proof of delivery quality water. The repair and construction organization must provide evidence refuting this information, otherwise the payment for the resources expended must be recalculated (decisions of the AS UO dated January 11, 2017 No. F09-10932 / 16 in case No. A60-59444 / 2015).

This provision is also confirmed by subparagraph “B” of paragraph 111 of the Rules for the provision of public services, which determines the date and time of the start of the provision of low-quality services in accordance with the date and time fixed by the devices intended for this (for example, OPU, IPU, etc.). Moreover, the presence of a meter and its readings eliminates the procedure for confirming the fact of providing services of inadequate quality in accordance with the requirements of section X of the Rules for the provision of public services (decisions of the AS PO dated January 16, 2017 No. F06-15316 / 2016 in case No. A12-4577 / 2016).

In cases where the relevant measuring instruments not installed on the building, to confirm the fact of the provision of poor-quality services, you will need to collect a number of documents, as well as follow the procedure specified in section X of the Rules for the provision of public services:

• fix the citizen's signal to the emergency dispatch service (paragraphs 105, 106, subparagraph "b" of paragraph 111);
• agree with the citizen on the timing of verification of the information provided about the violation, notify the repair and construction organization that the service it provides will be checked if the supplier does not know the reasons for the violation (clause 108);
• check at the consumer's signal, all data obtained in the course of it must be recorded in writing according to certain form(p. 109). The audit is intended to confirm a violation in the quality of the service provided (the act of measuring the temperature at the point of analysis in the living room) and to find out its causes (the act of measuring the temperature at the entrance to the house).

Summary tables and calculations compiled by the management company unilaterally, in the absence of quality control acts public service will not be accepted by the court as evidence (Resolution of the AC of the Central Organ of October 20, 2016 No. F10-2735 / 2016 in case No. A14-6593 / 2015).

Please note that the regulations do not connect the establishment of the fact of supply of a low-quality resource with the fact that the utility service provider recalculates the fee for the low-quality service to the owners of the premises (Resolution of the AS ZSO dated September 19, 2016 No. F04-3939/2016 in case No. A03-12727/2015), although such a condition can be included in the resource supply agreement on the basis of an agreement between the parties, and then it must be observed.

How is hot water calculated?

Subparagraph "D" of paragraph 22 of the Rules for Concluding Contracts for the Supply of Resources says that the recalculation of the cost of a poor-quality service is carried out in accordance with the Rules for the provision of public services. This is confirmed by the Decision of the Supreme Court of the Russian Federation No. AKPI13-394, which states that if there are no additional documents that fix the procedure for recalculation, a representative of citizens living in an apartment building can claim a reduction in fees for the provision of services in violation of their quality in accordance with the requirements of SanPin. Moreover, the recalculation should be carried out in the same way as the recalculation for direct consumers (decisions of the AC of the Central Organ of February 29, 2016 No. F10-5264 / 2015 in case No. A09-1717 / 2015).

Paragraph 101 of the Rules for the provision of public services prescribes to reduce the payment for hot water supply for the billing period by the total amount of payment for the entire period of provision of low-quality services in the cases specified in the documents (see Appendices 1 and 2 of the Rules for the provision of public services).

You can determine the total cost of services with a violation of quality by multiplying the cost of the service for the entire billing period (Appendix 2 of the Rules for the provision of public services) by the ratio of the duration of the provision of low-quality services within this period to the total duration of the provision of public services for the billing period.

The following values ​​are used to calculate utility bills for hot water supply:

Pi - the amount of payment for the provided utility service for the billing period (according to Appendix 2 to the Rules for the provision of utility services);

Δ - the total amount of payment for all days of the provision of low-quality services (or the amount by which the payment should be reduced for the billing period);

t - the duration of the provision of low-quality services within one billing period.

The duration of the billing period is determined by the entire duration of the supply of energy resources in accordance with the principles of the constancy and non-stop of this process. Based on the previously described rules for calculating payment (paragraph 2 of clause 101 of the Rules for the provision of utility services), the following formula can be drawn up (assuming that the month consists of 31 days):

Δ = Рi x t / 31 days

Reduction of payment for violation of the temperature regime occurs according to following principle: payment is reduced by 0.1% for every 3°C that is different from the norm (Appendix 2 to the Rules for the provision of utilities) and for each hour in the aggregate throughout the entire billing period in accordance with Section IX of the Rules for the provision of utilities. If the temperature of hot water falls below 40 °C, then each hour of provision of the service in this way in the aggregate for the entire billing period is paid at the rate of payment for the use of cold water.

The calculations are based on the following parameters:

• the amount of payment for the relevant service for the billing period, within which failures in the organization of hot water supply were recorded (Pi1);
• the amount by which the payment for the service is reduced (in %) varies depending on fluctuations in water temperature: - 0.1% for every 3 °C;
• the duration of the provision of services with quality violations in the aggregate for the entire billing period, expressed in hours, (t1) and taking into account the rule of section IX of the already mentioned rules.

Based on all the above information, the calculation of the amount of the fee reduction is carried out according to following algorithm:

Δ = Рi1 x % x t1

The provision of paragraph 5 of Appendix 1 to the Rules for the Provision of Public Services makes it possible to apply exactly this formula, despite the prescriptions of paragraph 101 of the same Rules.

Unfortunately, in the definitions given earlier there are rough edges that cause numerous disputes and even lead to filing claims. Basically, the misunderstanding is related to two values, the first of which (Pi1) helps to determine the size of the reduction in pay. According to paragraph 5 of App. 1 to the Rules for the provision of public services, this payment is characterized as payment for the billing period within which temperature violations were made. However, it is worth considering in more detail the concept of the billing period and outline its scope.

Paragraph 37 of the Rules for the provision of public services speaks of the billing period as a period of time equal to one calendar month. This is confirmed by calculations in the Letter of the Ministry of Regional Development of the Russian Federation dated June 04, 2007. No. 10611-YuT/07. It is known that in private clarifications the Ministry of Construction is also of the opinion that a monthly fee should be taken into account in the calculation.

It should be noted that the definitions current Rules provision of communal services coincide in meaning with the wording that has already ceased to have its meaning in the form of performance criteria in the part under consideration (paragraph 5 of Appendix 1).

Paragraph 101 of the Rules for the Provision of Utility Services states that payment for services for a billing period equal to a month is subject to a reduction by the total amount of payment for each period for the provision of services with violations equal to one day. Thus, it is necessary to calculate the cost of providing low-quality services for 1 day.

The decision of the Supreme Court of the Russian Federation No. AKPI13-394 decides that clause 5 of Appendix 1 to the Rules for the Provision of Public Services fixes such a change in the rules for paying for public services of insufficient quality, in which it is impossible not to pay at all for the supplied water with a violation of quality. If we take the value of the payment for the month as the value of the Pi1 parameter, then even in the case of short and non-serious violations, the amount of the reduction in payment will very quickly approach this indicator, and the citizen will have to be exempted from paying for the hot water supply service for the month in question. Based on this thesis, often judges reject the claims of managers apartment buildings who provided calculations of the amount of payment, taking into account the amount of payment per month.

So, the Decree of the AC VBO of October 14, 2016 No. No. F01-3504/2016 in case No. A39-6742/2014 says that the developed system of payment for the period of poor-quality implementation of the water supply service, in which the degree of reduction in the amount of payment for the supply of hot water is considered cumulatively for the billing month, implies the possibility of not paying a spent low-quality resource, however, this is wrong. If we take the case in which the temperature of the water supplied to consumers was below the norm by 18 ° C continuously for 9 days, then according to such a calculation system, the payment for hot water per month will be 00 rubles. 00 kop. Having studied in more detail paragraph 101 of the Rules for the provision of public services, one can understand that the settlement period for the provision of a service with a violation of quality should be considered 1 day, which is confirmed by the opinion of many representatives of the panel of judges (see the decisions of the AS ZSO of October 25, 2016 No. F04-4511 / 2016 in the case No. А45-26014/2015, AS UO dated 31.03.2017 No. Ф09-1379/17 in case No. А60-14516/2016, dated 06.02.2017 No. Ф09-11636/16 in case No. А71-4808/2015).

However, in some cases, the judges take the other side and recognize the legitimacy of calculating the amount of payment with a billing period of one month (see, for example, the Decree of the AC ZSO dated 15.06.2016 No. F04-2184 / 2016 in case No. A03-21553 / 2014).

As a possible way out, managers of an apartment building can request from the Ministry of Construction documentary evidence of an objective procedure for calculating a reduction in payment for hot water supply of inadequate quality, which can be used in court as an evidence base. However, the court has the right not to accept this document as evidence, substantiating its position by the fact that the proposed documents do not have the status of normative acts.

In the case when the amount of payment for one day is taken as the basis and a meter is installed on the house, it is more correct to make calculations based on the actual amount of water used per day, which was recorded by the device. If there is no counter, then the calculations are carried out using a formula that requires dividing the total amount of the resource accounted for and delivered to the house by the number of days in the month.

Clause 5 of Appendix 1 to the Rules for the Provision of Public Services prescribes a reduction in the amount of payment for hot water by 0.1% for every 3 ° C of violation of the norm. The following criteria are also introduced here: a deviation from temperature standards 5°C at night and 3°C during the day. Thus, the exact interpretation of this regulation implies that the payment for consumed hot water should not be reduced if its temperature at night did not fall over 55 °C and below 57 °C during the day. However, if the temperature continues to fall from the already reduced levels, then for every subsequent 3°C ​​(i.e. up to 54°C), the payment will be reduced by 0.1% every hour (at 51°C - 0.2%, etc.). d.). This approach also found support among representatives of the arbitration (decisions of the AC UA of March 31, 2017 No. F09-1379 / 17 in case No. A60-14516 / 2016, the Arbitration Court of the Far East of May 24, 2016 No. F03-976 / 2016 in case No. A24-1520 / 2015).

But Decision of the Armed Forces of the Russian Federation No. AKPI13-394 says that the establishment in paragraph 5 of Appendix 1 to the Rules for the provision of public services tolerances from the temperature regime prescribed by SanPiN 2.1.4.2496-09, in fact, means making adjustments to the sanitary and epidemiological standards governing the level of hot water quality, aimed at observing anti-epidemic measures. Such a situation is in conflict with the already mentioned legislative norms and requires the recognition of this norm as invalid in this context. Thus, we return to the fact that any deviation from the prescribed norms will be equated to violations of the quality of the service. The discussed criteria continue to apply in terms of the conditions and procedure for changing the amount of payment. Based on this, it can be concluded that a percentage of 0.1% reduction in payment for the use of hot water of inadequate quality should be charged for any violation of the temperature regime (starting from 57°C during the day and 55°C at night). In accordance with the documentary base, this approach looks more correct. He also finds support in the judiciary.

Guided by these considerations, the managers of apartment buildings should support their position with a calculation that promises great benefits, and build their line on the fact that no deviation from the temperature standards should be allowed.

There is also a nuance related to whether it is possible to calculate the exact amount of payment reduction if the deviation from the norm does not coincide with the “step” prescribed in the regulations. There is a point of view that recommends calculating the reduction in tenths of the payment if the temperature drops by less than 3°C. An example can be given when the water temperature during the daytime dropped to 55°C. In this case, it is possible to calculate that the percentage of the reduction in the payment for the service will be 0.167% (5/3 x 0.1%). However, the question arises as to the legitimacy of such calculations. Paragraph 5 of Appendix 1 to the Rules for the Provision of Public Services does not allow us to say that this correct solution. We remember that for every 3°C the payment decreases by 0.1%, this allows us to deduce a certain pattern.

It is this method of carrying out the calculation that is given in the Letter of the Ministry of Regional Development of the Russian Federation No. 10611-YuT / 07. A Resolution of the AS UO dated October 28, 2016 No. No. F09-9955/16 in case No. A71-5017/2015 emphasizes that the calculation of the Criminal Code is incorrect, because takes tenths of a degree into account.

Expert opinion

Why control the quality of hot water

A.N. Sokolova,

tax lawyer

The reality is that direct consumers of hot water supply (ordinary citizens, schools, kindergartens and other organizations) cannot from a technical point of view using necessary equipment control the quality of hot water, determine its characteristics such as color, turbidity, the amount of iron contained in water, and other substances, etc. Also, not everyone can seek legal advice. All this implies that producers and suppliers of heat and energy resources must approach their duties with full responsibility.

A similar position is also manifested in the implementation of strict control over the quality of services provided, in the prompt elimination of identified violations and the implementation of the correct calculation of citizens for the services provided in this case. Such a result can be achieved if all parties to the process of providing the population and other subjects with heat energy direct their efforts to control the quality of the services provided. It is important that the organizations responsible for the provision of energy resources in the matter of payment for services be guided by the letter of the law and do not insist on payments for cases of quality violations. Their actions should be based on the following regulations:

• paragraph 2 of Art. 542 of the Civil Code of the Russian Federation - for organizations engaged in the supply of energy resources;
• Rules for the provision of public services - for management companies.

If these standards are not adhered to, it will be very difficult to get the supplier companies to take proper measures to eliminate possible violations in the process of supplying energy resources. Violations of the rules for the provision of services in this area and the implementation of an incorrect calculation of the population for the low-quality resources provided do not allow optimizing the state of affairs in this area in many settlements.

Introduction:

The topic of calculating utility bills is one of the most difficult. For those who have not encountered the problem before, it is difficult to figure it out right away, and there seems to be no time for this.

However, let's try.

For calculations, RF GD No. 354 (procedure and methods for all occasions), RF GD No. 307 (only for heating and only until July 1, 2016, then RF GD No. 354 is valid), RF GD No. 306 (standards).

The text of the documents is complex, practically inaccessible to the mass payer. There is no clear notation physical quantities, which can confuse the reader, there are no names of physical quantities used in the calculation formulas and explanations. As if they were writing for themselves. Type we know ourselves, but the rest of us do not need to know.

And one more initial remark. Gentlemen from the Criminal Code and from the Developer often show great joy regarding the "energy efficiency" of new buildings, in particular in our area.

The essence of energy efficiency is a strict accounting of all communal resources and measures to save them. Let's see in the course of the discussion how justified such "joy".

Because we have a system DHW closed, that is, non-centralized, then the corresponding section of the RF PP No. 354 (Appendix 2, Section IV) is used for calculations, when the production of a utility service, in this case hot water supply, is carried out by the contractor (MC) on our ITP equipment with you from the common property.

Regarding this very concept of "production" of hot water supply by the contractor, we will not go into details for now. This is a separate rather "muddy" and controversial topic, who actually produces what and how.

We only note that according to the RF GD No. 354, clause 54 of the Rules, it is clearly defined that the payment for the maintenance of common property ( ITP equipment where the service provider heats water for domestic hot water) is charged separately. That is, "production" - operating costs for this common property are included in the payment for the maintenance and repair of common property and are not included in the calculation of payment for hot water supply.

So, what should be taken into account when calculating the DHW fee?

Total consumption of cold drinking water(via the cold water line) supplied for heating for hot water supply.

The total consumption of thermal energy taken in boilers from the heat carrier from the centralized supply of thermal energy (heating).

Everything seemed simple. I divided the total heat consumption (heating) by the total volume of cold water that was used for hot water supply and the order. Got specific consumption heat per cubic meter of hot water.

However, in our receipts there is no accounting for the total volume of cold water and hot water separately.

And the data individual consumption for hot water and cold water, it cannot be used due to the systematic measurement error of apartment meters. Therefore, the concept of ODN was introduced to eliminate this systematic error and to accurately calculate the total water consumption for the entire house by a common house meter.

In this sense, RF PP No. 354 is not quite correct and the campaign has long been outdated in some places, when it is proposed to use the total readings of the IPU as the basis for the calculations, if there is no common house meter, but at the same time, the authors of the regulatory text completely forgot about the systematic error of the apartment IPU (dead zone IPU at low water flow rates).

According to the law "On Energy Saving ...", the first thing to be done is to install common house metering devices, and where there is no technical possibility due to the design of the house, the technical possibility must be created by reconstructing (attaching) the premises for the installation of utility metering units.

The general house accounting of communal resources is not beneficial for public utilities, and therefore the process is sabotaged. AT " muddy water» cheating is easier.

Also, we don’t have a separate accounting for the consumption of thermal energy in the ITP, which is spent on DHW heating. At least this is not evident from the content of the information given in the receipt.

But what about the super duper energy efficient ITP? Isn't that too easy for a super duper energy efficient "space tech" ITP?

Have you installed one common cold water meter and one common heat energy meter for the entire unit and are happy like elephants?

And according to the Law, each individual house must be equipped with metering devices.

How does it differ then our ITP from the usual heating unit of the old Soviet house?

Why do we get "over the ears" every year about energy efficiency?

I'm looking for some crook - a "money pump" under an energy service contract "authoritatively" to say that we need to install metering devices to improve energy efficiency.

It is already clear to us that a comprehensive accounting of communal resources is needed.

Who prevented the installation of a two-channel heat energy meter? Was it difficult to plug in a meter to account for the consumption of make-up water for the DHW system?

And if they do exist, then why are their readings not used in calculations and not indicated in receipts?

Water consumption for the needs of hot water supply should be determined according to the norms of hot water consumption, taking into account the likelihood of using water taps. Determine the load on DHW system according to the maximum consumption of hot water and take it into account when choosing a heat source. Hello dear friends! We are used to using hot water every day and can hardly imagine comfortable life if you can not take a warm bath or you have to wash dishes under a tap from which a cold trickle pours. Water of the desired temperature and in the right amount is what the owner of every private house dreams of. Today we will determine the estimated consumption of water and heat for the hot water supply of our house. You must understand that at this stage it is not particularly important for us where we get this heat. Perhaps we will take it into account when choosing the power of the heat supply source and will heat water for the needs of hot water supply in the boiler. Perhaps we will heat the water in a separate electric boiler or a gas column, and perhaps it will be brought to us.

Well, what if there are no technical capabilities to carry out the hot water system at home, then we will go to our own or village bath. Our parents mostly went to the city baths, and now a mobile Russian bath has called under your window. Of course, life does not stand still and the presence of a bathtub and a shower cabin in the house today is no longer a luxury, but a simple necessity. Therefore, we will provide a hot water system in the house. The amount of load on the hot water supply system at home and, ultimately, the choice of heat source power will depend on the correct calculation of hot water supply. So come to this calculation need to be very serious. Before choosing the scheme and equipment of the DHW system at home, we need to calculate the main parameter of any system - the maximum hot water consumption per hour of maximum water consumption (Q g.v max, kg / h).

Practically, with the help of a stopwatch and a measuring container, we determine the flow of hot water, l / min when filling the bath

Calculation of the hourly maximum consumption of hot water per hour of its maximum water consumption

To calculate this consumption, let's turn to the hot water consumption rates (according to chapter SNiP 2-34-76), see table 1.

Hot water consumption rates (according to the chapter SNiP 2-34-76)

Table 1

g i.s - average for the heating period, l / day;

g and - the highest water consumption, l / day;

g i.h - the highest water consumption, l / h.

Dear friends, I want to warn you against one common mistake. Many developers, and even young inexperienced designers, calculate the hourly maximum flow hot water formula

G max =g and.h *U, kg/h

g i.h - hot water consumption rate, l / h, the highest water consumption, is taken according to table 1; U - the number of consumers of hot water, U = 4 people.

G max = 10 * 4 = 40 kg/h or 0.67 l/min

Q g.v max \u003d 40 * 1 * (55 - 5) \u003d 2000 kcal/h or 2.326 kW

Having calculated the water flow in this way and choosing the power of the heat source to heat this flow, you calmed down. But getting under the shower, you will be surprised to find that only 3 drops of water per second drip on your dirty and sweaty bald head. Neither washing your hands, nor rinsing the dishes, not to mention taking a bath, is out of the question. So what's the deal? And the mistake is that the maximum hourly water consumption for the day of the highest water consumption is not correctly determined. It turns out that all hot water consumption rates according to Table 1 should only be used to calculate the flow rate through individual devices and the probability of using their action. These norms are not applicable for determining costs based on the number of consumers, by multiplying the number of consumers by the specific consumption! This is precisely the main mistake made by many calculators when determining the heat load on the DHW system.

If we need to determine the performance of heat generators (boilers) or heaters in the absence of hot water storage tanks for subscribers (our case), then the estimated load on the DHW system must be determined by the maximum hourly consumption of hot water (heat) per day of the highest water consumption according to the formula

Q g.v max =G max * c * (t g.sr -t x), kcal/h

G max - the maximum hourly consumption of hot water, kg / h. The maximum hourly consumption of hot water, G max, taking into account the likelihood of using water folding devices, should be determined by the formula

G max = 18 *g * K and * α h * 10 3, kg / h

g - hot water consumption rate, l / with water folding devices. In our case: for a washbasin g y \u003d 0.07 l / s; for washing g m = 0.14 l / s; for a shower g d \u003d 0.1 l / s; for a bath g in \u003d 0.2 l / s. Choose greater value, that is, g \u003d g in \u003d 0.2 l / s; K and - dimensionless coefficient of use of a water-folding device for 1 hour of the highest water consumption. For a bathtub with a characteristic (highest) flow rate of hot water g x \u003d 200 l / h, given coefficient will be equal to K and = 0.28; α h is a dimensionless value determined depending on the total number N of water-folding devices and the probability of using them Р h for 1 hour of the highest water consumption. In turn, the probability of using water folding devices can be determined by the formula

R h =g and.h *U / 3600 * K and *g*N

g i.h - hot water consumption rate per hour of the highest water consumption, l / h. It is taken according to table 1, g i.h = 10l / h; N is the total number of taps installed in the house, N = 4.

R h \u003d 10 * 4 / 3600 * 0.28 * 0.2 * 4 \u003d 0.0496. At R h< 0,1 и любом N по таблице (N * Р ч = 0,198) определяем α ч = 0,44

G max \u003d 18 * 0.2 * 0.28 * 0.44 * 10 3 \u003d 444 kg / h or 7.4 l / min.

Q g.v max \u003d 444 * 1 * (55 - 5) \u003d 22200 kcal / h or 25.8 kW

No, neither the desired temperature, nor the proper flow of hot water - discomfort

As you can see, dear friends, the consumption of water and, accordingly, heat has increased by about 10 times. In addition, the heat consumption for hot water supply (25.8 kW) is 2 times more than the total heat consumption for heating and ventilation of the house (11.85 + 1.46 = 13.31 kW). If this data is presented to the “Customer”, then his hair will stand on end and he will demand that they explain to him - what is the matter here? So let's help him. Tables 2 and 3 below will help us with this. Now let's turn to table 2 and calculate the hourly highest flow water when loading all water consumers at the same time. Adding all the typical flow rates, we get 530 l/h. As you can see, the total typical flow rate turned out to be more than the calculated one (444l/h) by 86 l/h. And this is not surprising, since the likelihood that all water folding devices will work at the same time is very small. We have and so the value of meeting the demand for hot water from the maximum is 84%. In reality, this value is even less - about 50%. Let's try to get a real value, for this we use table 3. Do not forget that hot water consumption rates are developed for consumers at t g.av = 55 ° C, but we will find costs from the table at t g.av = 40 ° C.

The minimum total consumption of hot water, with an average water temperature equal to tg.w = 40 ° C and the simultaneous operation of all water intake devices with a security of this flow rate of 84%, will be equal to G min \u003d [ (5 * 1.5) + (20 * 5) + (30 * 6) + (120 * 10)] * 0.84 \u003d 342.3 l / h (239.6 l / h at t g.v \u003d 55 ° C)

The maximum total consumption of hot water, with an average water temperature equal to 40 ° C and the simultaneous operation of all water intake devices with a security of this flow rate of 84%, will be equal to G max \u003d [ (15 * 3) + (30 * 5) + (90 * 6 ) + (200 * 15)] * 0.84 \u003d 869.4 l / h (608.6 l / h at t g.v \u003d 55 ° C)

The average consumption at t g.w. = 55 ° C will be equal to G medium = (G min + G max) / 2 = (239.6 + 608.6) / 2 = 424.1 l / h. So we got what we were looking for - 424.1 l / h instead of 444 l / h according to the calculation.

Hot water consumption rates for water-folding devices (chapter SNiP 2-34-76)

table 2

Hot water consumption rates for various water intake devices

Table 3

Fence point	Sink	Kitchen sink	Economical shower	Shower standard	Shower comfort.	Bath
DHW temperature, o C	35-40	55	40	40	40	40
Consumption time, min	1,5-3	5	6	6	6	10-15
Hot water consumption for household needs, l	5-15	20-30	30	50	90	120-200

Thus, when calculating hot water supply, it is imperative to take into account such nuances: the number of residents; frequency of using the bathroom, shower; the number of bathrooms where hot water is used; specifications plumbing elements (for example, the volume of the bathroom); the expected temperature of the heated water, as well as the likelihood of using water taps at the same time. In the following posts, we will take a closer look at three common hot water systems. Depending on the method of heating water, these systems, for private country house, subdivided: DHW with storage water heater(boiler); DHW with instantaneous water heater; DHW with a double-circuit boiler.

What do you think I'm doing?!!!

The obtained values ​​of water and heat consumption for DHW needs – G max \u003d 444 kg / h or 7.4 l / min and Q g.v max \u003d 22200 kcal / h or 25.8 kW we accept, with subsequent clarification, when choosing a heat source. Today we have completed the 4th point of our plan for the house - we have calculated the hourly maximum consumption of hot water for a private house. If you haven't joined yet, please join!

Sincerely, Gregory