What is a temperature chart for? Heating schedule for quality regulation of heat supply based on the average daily outdoor temperature

Computers have long and successfully worked not only on tables office workers, but also in production and technological processes. Automation successfully manages the parameters of building heat supply systems, providing inside them ...

The set required air temperature (sometimes changing during the day to save money).

But the automation must be correctly configured, give it the initial data and algorithms for work! This article discusses the optimal temperature graph heating - the dependence of the temperature of the coolant of the water heating system at various temperatures outside air.

This topic has already been discussed in the article about. Here we will not calculate the heat losses of the object, but consider the situation when these heat losses are known from previous calculations or from the data of the actual operation of the operating object. If the facility is operating, then it is better to take the value of heat loss at the calculated outdoor temperature from the statistical actual data of previous years of operation.

In the article mentioned above, to construct the dependences of the coolant temperature on the outdoor air temperature, a system of nonlinear equations is solved by a numerical method. This article will present "direct" formulas for calculating water temperatures on the "supply" and on the "return", which is an analytical solution to the problem.

About cell colors Excel sheet, which are used for formatting in articles, can be read on the page « ».

Calculation in Excel of the temperature graph of heating.

So, when setting the operation of the boiler and / or the heating unit from the outside temperature, the automation system must set the temperature schedule.

Perhaps it would be more correct to place the air temperature sensor inside the building and adjust the operation of the coolant temperature control system based on the temperature of the indoor air. But it is often difficult to choose the location of the sensor inside due to different temperatures in various premises object or due to the significant remoteness of this place from the thermal unit.

Consider an example. Let's say we have an object - a building or a group of buildings that receives thermal energy from one common closed source of heat supply - a boiler house and / or a thermal unit. A closed source is a source from which the selection of hot water for water supply is prohibited. In our example, we will assume that, in addition to the direct selection of hot water, there is also no heat extraction for heating water for hot water supply.

To compare and verify the correctness of the calculations, we take the initial data from the above article "Calculation of water heating in 5 minutes!" and compose in Excel a small program for calculating the heating temperature graph.

Initial data:

1. Estimated (or actual) heat loss of an object (building) Q p in Gcal/h at design outdoor air temperature t nr write down

to cell D3: 0,004790

2. Estimated air temperature inside the object (building) t time in °C enter

to cell D4: 20

3. Estimated outdoor temperature t nr in °C we enter

to cell D5: -37

4. Estimated supply water temperature t pr enter in °C

to cell D6: 90

5. Estimated return water temperature t op in °C enter

to cell D7: 70

6. Indicator of non-linearity of heat transfer of applied heating devices n write down

to cell D8: 0,30

7. The current (of interest to us) outdoor temperature t n in °C we enter

to cell D9: -10

Values ​​in cellsD3 – D8 for a specific object are written once and then do not change. Cell valueD8 can (and should) be changed by determining the coolant parameters for different weather.

Calculation results:

8. Estimated water flow in the system GR in t/h we calculate

in cell D11: =D3*1000/(D6-D7) =0,239

GR = QR *1000/(tetc — top )

9. Relative heat flux q determine

in cell D12: =(D4-D9)/(D4-D5) =0,53

q =(tvr — tn )/(tvr — tnr )

10. The temperature of the water at the "supply" tP in °C we calculate

in cell D13: =D4+0.5*(D6-D7)*D12+0.5*(D6+D7-2*D4)*D12^(1/(1+D8)) =61,9

tP = tvr +0,5*(tetc – top )* q +0,5*(tetc + top -2* tvr )* q (1/(1+ n ))

11. Return water temperature tabout in °C we calculate

in cell D14: =D4-0.5*(D6-D7)*D12+0.5*(D6+D7-2*D4)*D12^(1/(1+D8)) =51,4

tabout = tvr -0,5*(tetc – top )* q +0,5*(tetc + top -2* tvr )* q (1/(1+ n ))

Calculation in Excel of the water temperature at the "supply" tP and on the return tabout for selected outdoor temperature tn completed.

Let's make a similar calculation for several different outdoor temperatures and build a heating temperature graph. (You can read about how to build graphs in Excel.)

Let's reconcile the obtained values ​​​​of the heating temperature graph with the results obtained in the article "Calculation of water heating in 5 minutes!" - the values ​​match!

Results.

The practical value of the presented calculation of the heating temperature graph lies in the fact that it takes into account the type of installed devices and the direction of movement of the coolant in these devices. Heat transfer non-linearity coefficient n, which has a significant effect on the temperature graph of heating in different devices different.

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What should be the temperature of the coolant in the heating system in order to live comfortably in the house? This point is of interest to many consumers. When choosing a temperature regime, several factors are taken into account:

• the need to achieve the desired degree of space heating;
• ensuring reliable, stable, economical and long-term operation heating equipment;
• efficient transfer of thermal energy through pipelines.

The temperature of the coolant in the heating network

The heating system must function in such a way that it is comfortable to be in the room, which is why the standards are established. According to regulatory documents, temperature in residential buildings should not fall below 18 degrees, and for children's institutions and hospitals - this is 21 degrees of heat.

But it should be borne in mind that, depending on the air temperature outside the building, the building through the enclosing structures may lose different size heat. Therefore, the temperature of the coolant in the heating system, based on external factors, varies from 30 to 90 degrees. When water is heated above, decomposition begins in the heating structure coatings which is prohibited by health regulations.

To determine what the temperature of the coolant in the batteries should be, specially designed temperature charts are used for specific groups of buildings. They reflect the dependence of the degree of heating of the coolant on the state of the outside air. You can also use automatic adjustment according to indications located indoors.

Optimum temperature for the boiler room

To ensure efficient heat transfer in heating boilers, there should be more heat because than more heat can transfer a certain amount of water, the better the degree of heating. Therefore, at the outlet of the heat generator, they try to bring the temperature of the liquid closer to the maximum allowable values.

In addition, the minimum heating of water or other coolant in the boiler cannot be lowered below the dew point (usually this parameter is 60-70 degrees, but it largely depends on technical features unit model and type of fuel). Otherwise, when the heat generator burns, condensate appears, which, in combination with aggressive substances contained in the composition flue gases, leads to increased wear of the device.

Coordination of water temperature in the boiler and system

There are two options for coordinating high-temperature coolants in the boiler and lower temperatures in the heating system:

1. In the first case, the efficiency of the boiler should be neglected and, at the exit from it, the coolant should be given out to such a degree of heating that the system currently requires. This is how small boilers operate. But in the end, it turns out not always to supply the coolant in accordance with the optimal temperature regime according to the schedule (read: ""). AT recent times Increasingly, in small boiler houses, a water heating controller is mounted at the outlet, taking into account the readings, which fixes the coolant temperature sensor.
2. In the second case, the heating of water for transportation through networks at the outlet of the boiler room is maximized. Further, in the immediate vicinity of consumers,automatic control of the coolant temperature to the required values. This method is considered more progressive, it is used in many large heating networks, and since regulators and sensors have become cheaper, it is increasingly used in small heat supply facilities.

The principle of operation of heating regulators

The temperature controller of the coolant circulating in the heating system is a device that provides automatic control and adjustment temperature parameters water.

Composed this device shown in the photo, from the following elements:

• computing and switching node;
• operating mechanism on the hot coolant supply pipe;
• an actuating unit designed to mix in the coolant coming from the return. In some cases, set three-way valve;
• booster pump in the supply area;
• not always a booster pump in the "cold bypass" section;
• sensor on the coolant supply line;
• valves and stop valves;
• return sensor;
• outdoor air temperature sensor;
• several room temperature sensors.

Now it is necessary to understand how the temperature of the coolant is regulated and how the regulator functions.

At the outlet of the heating system (return), the temperature of the coolant depends on the volume of water that has passed through it, since the load is relatively constant. Covering the liquid supply, the regulator thereby increases the difference between the supply line and the return line to the required value (sensors are installed on these pipelines).

When, on the contrary, it is necessary to increase the flow of the coolant, then a booster pump is inserted into the heat supply system, which is also controlled by the regulator. In order to lower the temperature of the water inlet flow, a cold bypass is used, which means that part of the heat carrier that has already circulated through the system is again sent to the inlet.

As a result, the regulator, redistributing the heat carrier flows depending on the data recorded by the sensor, ensures compliance with the temperature schedule of the heating system.

Often, such a controller is combined with a hot water controller using one computing node. A device that regulates hot water supply is easier to manage and in terms of actuators. Using a sensor on the hot water supply line, the passage of water through the boiler is adjusted and, as a result, it steadily has a standard 50 degrees (read: "").

Advantages of using the regulator in heat supply

The use of the regulator in the heating system has the following positive aspects:

• it allows you to clearly maintain the temperature graph, which is based on the calculation of the temperature of the coolant (read: "");
• increased heating of water in the system is not allowed and thus economical consumption of fuel and thermal energy is ensured;
• heat production and its transportation take place in boiler houses at the most effective parameters, and the characteristics of the coolant and hot water required for heating are created by the regulator in the closest to the consumer thermal node or paragraph (read: " ");
• for all subscribers of the heating network, the same conditions are provided, regardless of the distance to the source of heat supply.

Watch also a video about the circulation of the coolant in the heating system:

The normative water temperature in the heating system depends on the air temperature. Therefore, the temperature graph for the supply of coolant to the heating system is calculated in accordance with weather conditions. In the article we will talk about the requirements of SNiP for the operation of the heating system for objects for various purposes.

from the article you will learn:

In order to economically and rationally use energy resources in the heating system, the heat supply is tied to the air temperature. The dependence of the water temperature in the pipes and the air outside the window is displayed as a graph. The main task of such calculations is to maintain comfortable conditions for residents in apartments. For this, the air temperature should be about + 20 ... + 22ºС.

The temperature of the coolant in the heating system

The stronger the frost, the faster the living quarters heated from the inside lose heat. To compensate for the increased heat loss, the temperature of the water in the heating system increases.

The calculations use normative indicator temperature. It is calculated according to special technique and included in the governing documents. This figure is based on the average temperature of the 5 coldest days of the year. The calculation is based on the 8 coldest winters over a 50-year period.

Why is the drawing up of a temperature schedule for the supply of coolant to the heating system happening in this way? The main thing here is to be ready for the most severe frosts that happen every few years. Climatic conditions in a particular region can change over several decades. This will be taken into account when recalculating the schedule.

The value of the average daily temperature is also important for calculating the margin of safety of heating systems. By understanding the ultimate load, you can accurately calculate the characteristics necessary pipelines, stop valves and other elements. This saves on the creation of communications. Given the scale of construction for urban heating systems, the amount of savings will be quite large.

The temperature in the apartment directly depends on how much the coolant is heated in the pipes. In addition, other factors also matter here:

• air temperature outside the window;
• wind speed. With strong wind loads, heat losses through doorways and windows increase;
• the quality of sealing joints on the walls, as well as the general condition of the decoration and insulation of the facade.

Building codes change as technology advances. This is reflected, among other things, in the indicators in the coolant temperature graph, depending on outdoor temperature. If the premises retain heat better, then energy resources can be spent less.

Developers in modern conditions more carefully approach the thermal insulation of facades, foundations, basements and roofs. This increases the value of objects. However, along with the growth of construction costs are reduced. The overpayment at the construction stage pays off over time and gives good savings.

The heating of the premises is directly affected not even by how hot the water in the pipes is. The main thing here is the temperature of the heating radiators. It is usually in the range of + 70 ... + 90ºС.

Several factors affect battery heating.

1. Air temperature.

2. Features of the heating system. The indicator indicated in the temperature chart for supplying coolant to the heating system depends on its type. AT single pipe systems heating of water up to + 105ºС is considered normal. Two-pipe heating due to better circulation gives a higher heat transfer. This allows you to reduce the temperature to + 95ºС. Moreover, if at the inlet the water needs to be heated, respectively, to + 105ºС and + 95ºС, then at the outlet its temperature in both cases should be at the level of + 70ºС.

So that the coolant does not boil when heated above + 100ºС, it is supplied to the pipelines under pressure. Theoretically, it can be quite high. This should provide a large supply of heat. However, in practice, not all networks allow water to be supplied under high pressure due to their deterioration. As a result, the temperature drops, and during severe frosts there may be a lack of heat in apartments and other heated premises.

3. The direction of the water supply to the radiators. At the top wiring, the difference is 2ºС, at the bottom - 3ºС.

4. Type of heaters used. Radiators and convectors differ in the amount of heat they give off, which means that they must work in different temperature conditions. Better performance heat transfer from radiators.

At the same time, the amount of heat released is affected, among other things, by the temperature of the outdoor air. It is she who is the determining factor in the temperature schedule for supplying coolant to the heating system.

When the water temperature is +95ºС, we are talking about the coolant at the entrance to the dwelling. Given the heat loss during transportation, the boiler room should heat it much more.

In order to supply water of the required temperature to the heating pipes in the apartments, a special equipment. It mixes hot water from the boiler room with the one that comes from the return.

Temperature chart for supplying coolant to the heating system

The graph shows what the water temperature should be at the entrance to the dwelling and at the exit from it, depending on the street temperature.

The presented table will help to easily determine the degree of heating of the coolant in the central heating system.

Temperature indicators of air outside, °С	Temperature indicators of water at the inlet, °С			Temperature indicators of water in the heating system, ° С		Temperature indicators of water after the heating system, °С

Representatives of utilities and resource-supplying organizations measure the water temperature using a thermometer. The 5th and 6th columns indicate the figures for the pipeline through which hot coolant. 7 column - for the return.

The first three columns indicate fever- these are indicators for heat generating organizations. These figures are given without taking into account heat losses that occur during the transportation of the coolant.

The temperature schedule for supplying coolant to the heating system is needed not only by resource-supplying organizations. If the actual temperature differs from the standard one, consumers have reasons to recalculate the cost of the service. In their complaints, they indicate how warm the air in the apartments is. This is the easiest parameter to measure. Inspecting authorities can already track the temperature of the coolant, and if it does not comply with the schedule, force the resource supplying organization to perform its duties.

A reason for complaints appears if the air in the apartment cools below the following values:

• in corner rooms in the daytime - below + 20ºС;
• in the central rooms in the daytime - below + 18ºС;
• in corner rooms at night - below +17ºС;
• in the central rooms at night - below +15ºС.

SNiP

Requirements for the operation of heating systems are fixed in SNiP 41-01-2003. Much attention in this document is given to security issues. In the case of heating, the heated coolant carries a potential hazard, which is why its temperature for residential and public buildings limited. It, as a rule, does not exceed + 95ºС.

If the water in the internal pipelines of the heating system is heated above + 100ºС, then the following safety measures are provided for at such facilities:

• heating pipes are laid in special mines. In the event of a breakthrough, the coolant will remain in these reinforced channels and will not be a source of danger to people;
• pipelines in high-rise buildings have special structural elements or devices that do not allow water to boil.

If the building has heating made of polymer pipes, then the temperature of the coolant should not exceed + 90ºС.

We have already mentioned above that in addition to the temperature schedule for supplying coolant to the heating system, responsible organizations need to monitor how hot the accessible elements of heating devices are. These rules are also given in SNiP. Permissible temperatures vary depending on the purpose of the room.

First of all, everything here is determined by the same security rules. For example, in children's and medical institutions allowable temperatures are minimal. AT in public places and there are usually no special restrictions for them at various production facilities.

Surface of heating radiators general rules should not be heated above +90ºС. If this figure is exceeded, Negative consequences. They consist, first of all, in the burning of paint on batteries, as well as in the combustion of dust in the air. This fills the indoor atmosphere with substances harmful to health. In addition, there may be harm to appearance heating appliances.

Another issue is safety in rooms with hot radiators. According to the general rules, it is supposed to protect heating devices, the surface temperature of which is above + 75ºС. Usually, lattice fences are used for this. They do not interfere with air circulation. At the same time, SNiP provides for mandatory protection of radiators in children's institutions.

In accordance with SNiP, Maximum temperature coolant varies depending on the purpose of the room. It is determined both by the characteristics of the heating of different buildings, and by security considerations. For example, in hospitals allowable temperature water in the pipes is the lowest. It is + 85ºС.

The maximum heated coolant (up to +150ºС) can be supplied to the following facilities:

• lobbies;
• heated pedestrian crossings;
• landings;
• technical premises;
• industrial buildings, in which there are no aerosols and dust prone to ignition.

The temperature schedule for supplying coolant to the heating system according to SNiP is used only in the cold season. In the warm season, the document in question normalizes the microclimate parameters only in terms of ventilation and air conditioning.

Maybe Russia is a cold country, but our apartments are warmer than in many European countries. Because it is central heating, subsidized by the state, and the British, Germans, French, deprived of this luxury, are forced to save and temper at the same time. It's in theory. But what about in practice? Is it good for you to heat and what to do if not?

Heating norms

Since central heating is a matter of state concern, the norms for heating in an apartment are determined centrally. GOST 30494-2011 says that during heating season temperature in living rooms ah, kitchen and bathrooms should not fall below 18 ° C. In cold regions, such as Yakutia or the Khabarovsk Territory, the temperature for living rooms is set from 20 ° C, and for the kitchen and bathroom - from 18 ° C.

From midnight to five o'clock in the morning, a decrease in the indicated norms by 3 ° C is allowed. During sleep, the human body needs less heat, and heating providers are legitimately taking advantage of this to save money.

If the specified GOST is a reference book for designers engineering systems, then all public utilities, without exception, compare hours and degrees with Decree of the Government of the Russian Federation No. 354 of 05/06/2011. It, in particular, establishes the beginning of the heating season. Batteries should be turned on on the sixth day after the temperature outside the window drops below 8°C. By the way, the rule of eight also applies to reverse side: as soon as the spring air reaches an average daily mark of 8 ° C and is able to maintain positions for five days in a row, the batteries will be turned off.

Often these limits heating period go against our personal comfort. Almost every autumn, communal services are bombarded with demands to turn on the heating in apartments earlier than planned, but they have every right to reject these demands, until, of course, the day specified by the Decree arrives.

How is the heating of apartment buildings

The heat that goes into our homes is generated at CHP or boiler houses. There, the water is heated to be piped into the houses. It must get to the batteries hot, so it must be very hot. Every schoolchild knows that water will boil at 100°C, but this does not happen with water in heating pipes.

A pressure of 7-8 atmospheres is created in the heat supply pipes, which raises the boiling point of water to 160-170°C.

Exist different schemes distribution of the heat carrier (this is how official documents call water in pipes and radiators) coming from the thermal power plant. In the most common, so-called independent scheme heating, water does not go directly to the apartments. First, it is sent to a heating point located in the basement of a high-rise building, where it passes through a heat exchanger and cools down to a temperature acceptable for supply to rooms. The water in the radiators should not be too hot - it is simply dangerous.

After passing through the radiators inside the house, the coolant, which has already cooled down by 25-35 ° C, returns to the same heat point - to heat up again and get into our homes.

Temperature in radiators

The only norm relating directly to heating batteries in apartment building, is the maximum coolant temperature. It should not exceed 95°C for two-pipe systems and 105°C for one-pipe systems. Finding out which system is installed in your apartment is easy: look at your radiator and count how many pipes are connected to it. Two-pipe systems are more widespread - they are more efficient and economical.

The lower limit of water temperature in heating batteries is not officially fixed in any way. The only rule: batteries must provide the established GOST 30494-2011 temperature norm in the rooms. It is clear, however, that if the batteries themselves are slightly warm, then they will not be able to heat the room to the 18 ° C required by GOST. Just a very, very small room.

What to measure and how to measure

So, the desired hour has come, and the heating season has begun, but the apartment is still cold. How to proceed?

The first step is to measure the heating in the apartment. In other words, measure the temperature in the rooms and compare it with the GOST standards indicated above (and listed in detail) to make sure that poor heating in the apartment - a reality, not your individual feelings.

If you have a base station, then you will see the exact air temperature in the form of a graph in your mobile application or web interface.

If all measurements comply with the rules, it is useless to complain, utilities will simply refer to the same GOST. You will have to insulate yourself.

However, if the measurements taken indicate that the heating temperature in the apartment does not correspond to the norm, then there are several options.

First you need to determine the cause of thermal problems.
Here is a short list of the most common:

1. Cork in batteries
Batteries can be cold due to the accumulation of air in the pipes - the so-called air locks. They prevent the water from circulating properly and proper heating in the apartment is broken. The plug can be removed by yourself by opening a special valve or, as it is also called, the Mayevsky tap. It is usually located near upper corner radiator. Be careful, and if you are not sure that you can fix the heating yourself, then it is better to seek help from a specialist.

2. Large heat loss of the apartment
A common problem in older homes is that the batteries are scalding hot, but still cold. It is useless to appeal to public utilities, you need to take care of thermal insulation on your own. Just don't get too carried away with sealing, because curing one can cripple the other. In particular, it often suffers from excessive warming measures. When installing airtight windows and filling cracks in the walls, think about how your rooms are.

Most apartments are heated with centralized system, which includes batteries located in every room of the house. The quality of the operation of this system is evidenced by the temperature of the radiator and the air temperature in the apartment.

Minimum temperatures

There is no document that would determine the norms for heating batteries. There are documents that regulate the temperature of the coolant and the temperature in the apartment. This can be explained by the different thermal conductivity of materials used for the production of heating batteries, as well as design features various models.

Cast iron, steel, copper and aluminum (they are most often used for the manufacture of radiators) have different thermal conductivity. This means that batteries made from these materials heat up and release heat differently. That is, provided that the coolant temperature at the inlet is 100 °C, it will not heat up to such a temperature. A copper device can (among the above 4 materials, copper conducts heat the best).

It would be possible to establish heating rates for radiators according to specific type material. However, the situation is complicated by manufacturers who use various tricks during development, as well as improving the heat dissipation of an individual device. So it is very difficult to develop universal temperature standards for water batteries.

Batteries heated to the same temperature with 5 and 11 create a different heat flux. Therefore, the room will warm up in different ways. In practice, when planning a water heating system, always calculate optimal dimensions and desired power heating batteries for each room. Therefore, when correct work of the entire heating system, the battery, which has a sensor and a thermostat, will give right amount heat.

It is best to measure the temperature of the coolant and check whether the resulting figure is normal. It can be done different ways. Some of these include measuring the temperature of the radiator and using correction values ​​depending on the material used to make the heating device.

Read also: Installation of bimetallic radiators

The minimum value of the coolant temperature is +30 °С (according to the resolution of the State Construction Committee dated September 27, 2003 No. 170). Such water should circulate through a system in which the coolant moves according to the “bottom-down” scheme when the outside temperature is +10 °C.

If it is 0 °С outside the window, water should flow to radiators having a sensor, as well as a device for adjusting the heating, not colder than +57 °С. The battery may reach nearly this temperature.

Maximum values

They are regulated by the document SNiP 41-01-2003 "Heating, ventilation and air conditioning". According to him, in a radiator with a temperature sensor, it is necessary to supply a coolant heated no more than:

• 95 ° С - when the water heating system is two-pipe;
• 105 °С - when heating system is single-pipe;
• 85-90 °C is the recommended upper limit. This recommendation is based on the fact that water boils at 100°C. Boiling is not allowed. Therefore, if such a coolant is supplied, then the managing organization is forced to apply additional measures to prevent boiling.

Long-term circulation of a coolant with a temperature of 115 ° C will quickly disable the radiators. It is better to supply water heated to 80 or 90 ° C.

How to measure the temperature of the coolant and radiator

The level of water heating is determined as follows:

1. Open the faucet.
2. Substitute a container with a thermometer placed in it.
3. Fill the container with water.
4. Waiting for the reaction of the measuring device.

The end result must be correct. Large deviations are possible. The maximum deviation is 4 °С. If it is -6 degrees outside and the coolant should be heated to 80 degrees, and the thermometer shows the number 84, then everything is fine. If there are downward deviations, then you need to go to the DEZ and file a complaint. If the batteries of the apartment are airy, then you should first go to the housing office.

The temperature of the radiator can be measured in one of 4 ways:

1. Take a thermometer, apply it to a radiator or heating pipe. 1-2 degrees are added to the result.
2. Use an infrared thermometer-pyrometer. This is a very accurate device. Thanks to special sensors, the error of the result is not more than 0.5 °C.
3. They take an alcohol thermometer, apply it to a water radiator and fix it using adhesive tape. The thermometer must be wrapped with foam rubber or any material with high thermal insulation properties. The fixed thermometer is left for long time and, looking at it, control the temperature heat flow and correct operation heating network, as well as adjust the battery performance.
4. Use such an electric measuring device, which has a "measure temperature" function. Use involves fixing a wire with a thermocouple and a sensor on a heat source. Then they turn it on and get a real figure.