Each heating system has certain characteristics. These include power, heat transfer and operating temperature. They determine the efficiency of work, directly affecting the comfort of living in the house. How to choose the right temperature schedule and heating mode, and its calculation?
Drawing up a temperature chart
Temperature chart The operation of the heating system is calculated using several parameters. Not only the degree of heating of the premises, but also the coolant consumption depends on the selected mode. This also affects the current costs of heating maintenance.
The compiled heating temperature schedule depends on several parameters. The main one is the level of water heating in the mains. It, in turn, consists of the following characteristics:
- Temperature in the supply and return pipeline. Measurements are taken in the corresponding boiler nozzles;
- Characteristics of the degree of air heating indoors and outdoors.
Correct calculation of the heating temperature schedule begins with calculating the difference between the temperatures hot water in the direct and supply pipes. This value has the following designation:
∆T=Tin-Tob
Where Tin– water temperature in the supply line, Tob– degree of water heating in the return pipe.
To increase the heat transfer of the heating system, it is necessary to increase the first value. To reduce coolant flow, ∆t should be minimal. This is precisely the main difficulty, since the temperature schedule of the heating boiler directly depends on external factors– heat losses in the building, air outside.
To optimize heating power, it is necessary to insulate the external walls of the house. This will reduce heat losses and energy consumption.
Temperature calculation
To determine the optimal temperature regime, it is necessary to take into account the characteristics of heating components - radiators and batteries. In particular, specific power (W/cm²). This will directly affect the thermal transfer of heated water to the air in the room.
It is also necessary to make a series preliminary calculations. This takes into account the characteristics of the house and heating devices:
- Heat transfer resistance coefficient of external walls and window designs. It must be at least 3.35 m²*C/W. Depends on the climatic characteristics of the region;
- Surface power of radiators.
The temperature graph of the heating system is directly dependent on these parameters. To calculate the heat loss of a house, you need to know the thickness of the external walls and the material of the building. The surface power of batteries is calculated using the following formula:
Ore=P/Fact
Where R– maximum power, W, fact– radiator area, cm².
According to the data obtained, a temperature regime for heating and a heat transfer graph are drawn up depending on the outside temperature.
To change heating parameters in a timely manner, install a heating temperature regulator. This device connects to outdoor and indoor thermometers. Depending on the current indicators, the operation of the boiler or the volume of coolant flow into the radiators is adjusted.
Weekly programmer is optimal temperature controller heating. With its help, you can automate the operation of the entire system as much as possible.
Central heating
For district heating, the temperature regime of the heating system depends on the characteristics of the system. Currently, there are several types of coolant parameters supplied to consumers:
- 150°C/70°C. To normalize the water temperature using elevator unit it mixes with the cooled flow. In this case, you can create an individual temperature schedule for the heating boiler room for a specific house;
- 90°С/70°С. Typical for small private heating systems designed to supply heat to several apartment buildings. In this case, you do not need to install the mixing unit.
The responsibility of utility services is to calculate the temperature heating schedule and control its parameters. In this case, the degree of air heating in residential premises should be at +22°C. For non-residential residents this figure is slightly lower – +16°C.
For centralized system drawing up the correct temperature schedule for the heating boiler room is required to ensure optimal comfortable temperature in apartments. The main problem is the lack feedback– it is impossible to regulate the coolant parameters depending on the degree of air heating in each apartment. This is why a temperature chart is drawn up. heating system.
A copy of the heating schedule can be requested from the Management Company. With its help you can control the quality of the services provided.
Heating system
Do similar calculations for autonomous systems Heating a private home is often not necessary. If the scheme includes indoor and outdoor temperature sensors– information about them will be sent to the boiler control unit.
Therefore, to reduce energy consumption, low-temperature heating modes are most often chosen. It is characterized by relatively low heating of water (up to +70°C) and a high degree of circulation. This is necessary for uniform heat distribution across all heating devices.
To implement such a temperature regime for the heating system, the following conditions will need to be met:
- Minimum heat losses in the house. However, one should not forget about normal air exchange - ventilation is mandatory;
- High thermal output of radiators;
- Installation of automatic temperature controllers in heating.
If there is a need to perform a correct calculation of the system’s operation, it is recommended to use special software systems. For self-calculation There are too many factors to consider. But with their help you can create approximate temperature graphs of heating modes.
However, it should be borne in mind that an accurate calculation of the heat supply temperature schedule is done for each system individually. The tables show the recommended values for the degree of heating of the coolant in the supply and return pipes depending on the outside temperature. When performing calculations, the characteristics of the building and the climatic features of the region were not taken into account. But even despite this, they can be used as a basis for creating a temperature chart for the heating system.
The maximum load of the system should not affect the quality of boiler operation. Therefore, it is recommended to purchase it with a power reserve of 15-20%.
Even the most accurate temperature schedule of a heating boiler room will exhibit deviations in calculated and actual data during operation. This is due to the operating features of the system. What factors can influence the current temperature regime of heat supply?
- Contamination of pipelines and radiators. To avoid this, the heating system should be cleaned periodically;
- Incorrect operation of the regulating and shut-off valves. The functionality of all components must be checked;
- Violation of the boiler operating mode – sharp jumps temperature as a consequence - pressure.
Maintaining the optimal temperature regime of the system is only possible with making the right choice its components. To do this, their operational and technical properties should be taken into account.
The battery heating can be adjusted using a thermostat, the operating principle of which can be found in the video:
Each management company strives to achieve economical heating costs apartment building. In addition, residents of private houses are trying to come. This can be achieved by drawing up a temperature graph that reflects the dependence of the heat produced by the carriers on the weather conditions outside. Proper Use This data allows you to optimally distribute hot water and heating to consumers.
What is a temperature graph
The coolant should not maintain the same operating mode, because outside the apartment the temperature changes. This is what you need to be guided by and, depending on it, change the temperature of the water in heating objects. Dependence of coolant temperature on outside temperature air is compiled by specialist technologists. To compile it, the values available for the coolant and the outside air temperature are taken into account.
During the design of any building, the size of the heat-providing equipment installed in it, the dimensions of the building itself and the cross-sections available in the pipes must be taken into account. In a high-rise building, residents cannot independently increase or decrease the temperature, since it is supplied from the boiler room. Adjustment of the operating mode is always carried out taking into account the temperature curve of the coolant. The temperature scheme itself is also taken into account - if the return pipe supplies water with a temperature above 70°C, then the coolant flow will be excessive, but if it is significantly lower, there will be a deficiency.
Important! The temperature schedule is drawn up in such a way that, at any outside air temperature in the apartments, a stable temperature is maintained. optimal level heating at 22 °C. Thanks to it, even the most severe frosts are not scary, because the heating systems will be ready for them. If it is -15 °C outside, then it is enough to track the value of the indicator to find out what the temperature of the water in the heating system will be at that moment. The harsher the weather outside, the hotter the water inside the system should be.
But the level of heating maintained indoors depends not only on the coolant:
- Outside temperature;
- The presence and strength of wind - its strong gusts significantly affect heat loss;
- Thermal insulation - high-quality structural parts of the building help to retain heat in the building. This is done not only during the construction of the house, but also separately at the request of the owners.
Table of coolant temperature versus outside air temperature
In order to calculate the optimal temperature regime, you need to take into account the characteristics of heating devices - batteries and radiators. The most important thing is to calculate their specific power; it will be expressed in W/cm2. This will most directly affect the transfer of heat from the heated water to the heated air in the room. It is important to take into account their surface power and the drag coefficient available window openings and external walls.
After all the values have been taken into account, you need to calculate the difference between the temperature in two pipes - at the entrance to the house and at the exit from it. The higher the value in the input pipe, the higher the value in the return pipe. Accordingly, indoor heating will increase under these values.
| Weather outside, C | at the entrance to the building, C | Return pipe, C |
| +10 | 30 | 25 |
| +5 | 44 | 37 |
| 0 | 57 | 46 |
| -5 | 70 | 54 |
| -10 | 83 | 62 |
| -15 | 95 | 70 |
Proper use of coolant involves attempts by house residents to reduce the temperature difference between the inlet and outlet pipes. It could be construction work for insulating a wall from the outside or thermal insulation of external heat supply pipes, insulating floors above a cold garage or basement, insulating the inside of a house, or several works performed simultaneously.
Heating in the radiator must also comply with the standards. In central heating systems it usually varies from 70 C to 90 C depending on the outside air temperature. It is important to consider that in corner rooms cannot be less than 20 C, although in other rooms of the apartment a decrease to 18 C is allowed. If the temperature outside drops to -30 C, then the heating in the rooms should rise by 2 C. In other rooms the temperature should also increase, provided that in rooms for various purposes it may be different. If there is a child in the room, then it can vary from 18 C to 23 C. In storerooms and corridors, heating can vary from 12 C to 18 C.
It is important to note! The average daily temperature is taken into account - if the temperature at night is about -15 C, and during the day - -5 C, then it will be calculated according to the value of -10 C. If at night it was about -5 C, and at daytime it rose to +5 C, then heating is taken into account at a value of 0 C.
Schedule for hot water supply to the apartment
In order to deliver optimal hot water to the consumer, CHP plants must send it as hot as possible. Heating lines are always so long that their length can be measured in kilometers, and the length of apartments is measured in thousands. square meters. Whatever the insulation of the pipes, heat is lost on the way to the user. Therefore, it is necessary to heat the water as much as possible. 
However, water cannot be heated above its boiling point. Therefore, a solution was found - to increase the pressure.
It is important to know! As it increases, the boiling point of water shifts upward. As a result, it reaches the consumer really hot. When the pressure increases, risers, mixers and taps are not affected, and all apartments up to the 16th floor can be provided with hot water supply without additional pumps. In a heating main, water usually contains 7-8 atmospheres, the upper limit is usually 150 with a margin.
It looks like this:
| Boiling temperature | Pressure |
| 100 | 1 |
| 110 | 1,5 |
| 119 | 2 |
| 127 | 2,5 |
| 132 | 3 |
| 142 | 4 |
| 151 | 5 |
| 158 | 6 |
| 164 | 7 |
| 169 | 8 |
Hot water supply to winter time year must be continuous. Exceptions to this rule include heat supply accidents. Hot water supply can only be turned off in summer period For preventative work. Such work is carried out both in heat supply systems closed type, and in open systems.
The standard water temperature in the heating system depends on the air temperature. Therefore, the temperature schedule for supplying coolant to the heating system is calculated in accordance with weather conditions. In this article we will talk about the SNiP requirements for the operation of a 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 relationship between the temperature of the water in the pipes and the air outside the window is displayed in the form of a graph. the main task Such calculations include maintaining comfortable conditions for residents in apartments. To do this, the air temperature should be about +20…+22ºС.
Coolant temperature in the heating system
The stronger the frost, the faster living spaces heated from the inside lose heat. To compensate for the increased heat loss, the temperature of the water in the heating system increases.
The standard temperature indicator is used in the calculations. It is calculated using a special method and entered into the management documentation. This indicator is based on the average temperature of the 5 coldest days of the year. For the calculation, the 8 coldest winters over a 50-year period are taken.
Why does drawing up a temperature schedule for the supply of coolant to the heating system happen this way? The main thing here is to be prepared for the most severe frosts, which 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 safety margin of heating systems. By understanding the maximum load, you can accurately calculate the characteristics of the required pipelines, shut-off valves and other elements. This saves on creating communications. Considering 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 hot the coolant in the pipes is. In addition, other factors are also important here:
- air temperature outside the window;
- wind speed. With strong wind loads, heat loss through doorways and windows increases;
- quality of sealing joints on walls, as well as general state finishing and insulation of the facade.
Building codes change as technology advances. This is reflected, among other things, in the indicators in the graph of the coolant temperature depending on the outside temperature. If rooms retain heat better, then less energy resources can be spent.
Developers in modern conditions more carefully approach the thermal insulation of facades, foundations, basements and roofs. This increases the cost of objects. However, at the same time as construction costs increase, heating and hot water costs decrease. Overpayment at the construction stage pays off over time and provides good savings.
The heating of rooms 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 within +70…+90ºС.
Several factors influence battery heating.
1. Air temperature.
2. Features of the heating system. The indicator indicated in the temperature schedule for the coolant supply to the heating system depends on its type. In single-pipe systems, heating water to +105ºС is considered normal. Due to better circulation, two-pipe heating provides 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.
To prevent the coolant from boiling 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 wear and tear. As a result, the temperature decreases and severe frosts There may be a lack of heat in apartments and other heated premises.
Observe the 4 main requirements for the quality of heat supply in apartment buildings. They are established by Appendix 1 to Rules No. 354. Help system experts have prepared a summary table with permissible deviations when supplying heat to the MKD.
3. Direction of water supply to radiators. With the upper wiring, the difference is 2ºС, with the lower wiring - 3ºС.
4. Type of heating devices used. Radiators and convectors differ in the amount of heat they give off, which means they must operate in different temperature conditions. Better performance heat transfer from radiators.
At the same time, the amount of heat released is influenced, among other things, by the temperature of the street air. It is this that is the determining factor in the temperature schedule of coolant supply to the heating system.
When the water temperature is +95ºС, we're talking about about the coolant at the entrance to the living space. Considering the heat loss during transportation, the boiler room must heat it much more.
To supply water to heating pipes in apartments desired temperature, special equipment is installed in the basement. It mixes hot water from the boiler room with that coming from the return.
Temperature graph of coolant supply to the heating system
The graph shows what the water temperature should be at the entrance to the living space and at the exit from it, depending on the street temperature.
The presented table will help you easily determine the degree of heating of the coolant in the system central heating.
|
Outside air temperature, °C |
Inlet water temperature, °C |
Temperature indicators of water in the heating system, °C |
Temperature indicators of water after the heating system, °C |
|||
Representatives of utility services and resource supply organizations measure water temperature using a thermometer. Columns 5 and 6 indicate the numbers for the pipeline through which the hot coolant is supplied. Column 7 – for return.
The first three columns indicate elevated temperature– these are indicators for heat generating organizations. These figures are given without taking into account heat losses occurring during the transportation of the coolant.
The temperature schedule for the supply of coolant to the heating system is needed not only by resource supply organizations. If the actual temperature differs from the standard temperature, consumers have grounds 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 fulfill its duties.
Is it possible to charge a fee for heating basements and loggias, whether to recalculate for a bathroom and how to calculate the fee when the radiator is dismantled - read the answers to these and other questions in the expert article.
A reason for complaints appears if the air in the apartment cools below the following values:
- in corner rooms during the daytime – below +20ºС;
- in the central rooms during 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 set out in SNiP 41-01-2003. Much attention is paid to security issues in this document. In the case of heating, the heated coolant poses a potential danger, which is why its temperature for residential and public buildings limited. As a rule, it does not exceed +95ºС.
If the water in the internal pipelines of the heating system heats up above +100ºС, then the following safety measures are provided at such facilities:
- Heating pipes are laid in special shafts. 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 prevent water from boiling.
If the building has heating from polymer pipes, then the coolant temperature should not exceed +90ºС.
We have already mentioned above that in addition to the temperature schedule for the supply of coolant to the heating system, responsible organizations need to monitor how hot the available heating elements 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 safety rules. For example, in children's and medical institutions permissible temperatures are minimal. IN in public places and there are usually no special restrictions placed on them at various production facilities.
The surface of heating radiators general rules should not be heated above +90ºС. When this figure is exceeded, Negative consequences. They consist, first of all, in the burning of paint on the batteries, as well as in the combustion of dust in the air. This fills the indoor atmosphere with substances that are harmful to health. In addition, there may be harm to appearance heating devices.
Another issue is ensuring safety in rooms with hot radiators. According to general rules, it is necessary to protect heating devices, whose surface temperature is above +75ºС. Typically, lattice fencing is used for this. They do not interfere with air circulation. At the same time, SNiP requires 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 heating characteristics of different buildings and by safety considerations. For example, in medical institutions permissible temperature the water in the pipes is the lowest. It is +85ºС.
The maximum heated coolant (up to +150ºС) can be supplied to the following objects:
- lobbies;
- heated pedestrian crossings;
- landings;
- technical premises;
- industrial buildings that do not contain aerosols and dust prone to fire.
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 microclimate parameters only from the point of view of ventilation and air conditioning.
Economical energy consumption in the heating system can be achieved if certain requirements are met. One option is to have a temperature diagram, which reflects the ratio of the temperature emanating from the heating source to external environment. The values of the values make it possible to optimally distribute heat and hot water to the consumer.
High-rise buildings are mainly connected to central heating. Sources that convey thermal energy, are boiler houses or thermal power plants. Water is used as a coolant. It is heated to a given temperature.
Having passed full cycle According to the system, the coolant, already cooled, returns to the source and reheating occurs. Sources are connected to consumers by heating networks. Since the environment changes temperature, thermal energy should be adjusted so that the consumer receives the required volume.
Heat regulation from central system can be done in two ways:
- Quantitative. In this form, the water flow changes, but its temperature remains constant.
- Qualitative. The temperature of the liquid changes, but its flow does not change.
In our systems, the second regulation option is used, that is, qualitative. Z Here there is a direct relationship between two temperatures: coolant and environment. And the calculation is carried out in such a way as to ensure the heat in the room is 18 degrees and above.
Hence, we can say that the temperature graph of the source is a broken curve. The change in its directions depends on temperature differences (coolant and outside air).
The dependency schedule may vary.
A specific diagram has a dependency on:
- Technical and economic indicators.
- CHP or boiler room equipment.
- Climate.
High coolant values provide the consumer with great thermal energy.
Below is an example of a diagram, where T1 is the coolant temperature, Tnv is the outside air:
A diagram of the returned coolant is also used. A boiler house or thermal power plant can estimate the efficiency of the source using this scheme. It is considered high when the returned liquid arrives chilled.
The stability of the scheme depends on the design values of fluid flow of high-rise buildings. If the flow through the heating circuit increases, the water will return uncooled, as the flow rate will increase. And vice versa, when minimum consumption, the return water will be sufficiently cooled.
The supplier's interest, of course, is in the supply of return water in a cooled state. But there are certain limits for reducing consumption, since a decrease leads to loss of heat. The consumer’s internal temperature in the apartment will begin to drop, which will lead to a violation building codes and the discomfort of ordinary people.
What does it depend on?
The temperature curve depends on two quantities: outside air and coolant. Frosty weather leads to an increase in coolant temperature. When designing a central source, the size of the equipment, building and pipe size are taken into account.
The temperature leaving the boiler room is 90 degrees, so that at minus 23°C, the apartments are warm and have a value of 22°C. Then the return water returns to 70 degrees. Such standards correspond to normal and comfortable living in the house.
Analysis and adjustment of operating modes is carried out using a temperature diagram. For example, the return of liquid with an elevated temperature will indicate high costs coolant. Underestimated data will be considered a consumption deficit.
Previously, for 10-story buildings, a scheme with calculated data of 95-70°C was introduced. The buildings above had their own chart of 105-70°C. Modern new buildings may have a different layout, at the discretion of the designer. More often, there are diagrams of 90-70°C, and maybe 80-60°C.
Temperature chart 95-70:
Temperature chart 95-70
How is it calculated?
A control method is selected, then a calculation is made. The calculated winter and reverse order of water supply, the amount of outside air, and the order at the break point of the diagram are taken into account. There are two diagrams: one of them considers only heating, the second considers heating with hot water consumption.
For an example of calculation, we will use methodological development"Roskommunenergo".
The input data for the heat generating station will be:
- Tnv– the amount of outside air.
- TVN- indoor air.
- T1– coolant from the source.
- T2– reverse flow of water.
- T3- entrance to the building.
We will look at several heat supply options with values of 150, 130 and 115 degrees.
At the same time, at the exit they will have 70°C.
The results obtained are compiled into a single table for subsequent construction of the curve:
So we got three various schemes, which can be taken as a basis. It would be more correct to calculate the diagram individually for each system. Here we examined the recommended values, without taking into account the climatic features of the region and the characteristics of the building.
To reduce energy consumption, just select a low temperature setting of 70 degrees and uniform heat distribution throughout the heating circuit will be ensured. The boiler should be taken with a power reserve so that the system load does not affect the quality operation of the unit.
Adjustment
Heating regulator
Automatic control is provided by the heating regulator.
It includes the following parts:
- Computing and matching panel.
- Actuator on the water supply section.
- Actuator, which performs the function of mixing liquid from the returned liquid (return).
- Boost pump and a sensor on the water supply line.
- Three sensors (on the return line, on the street, inside the building). There may be several of them in the room.
The regulator closes the liquid supply, thereby increasing the value between return and supply to the value specified by the sensors.
To increase the flow, there is a boost pump and a corresponding command from the regulator. The incoming flow is controlled by a "cold bypass". That is, the temperature decreases. Some of the liquid that has circulated along the circuit is sent to the supply.
Sensors collect information and transmit it to control units, resulting in a redistribution of flows that provide a rigid temperature scheme for the heating system.
Sometimes, a computing device is used that combines hot water and heating regulators.
The hot water regulator has more simple diagram management. The hot water sensor regulates the flow of water with a stable value of 50°C.
Advantages of the regulator:
- The temperature scheme is strictly maintained.
- Elimination of overheating of the liquid.
- Fuel efficiency and energy.
- The consumer, regardless of the distance, receives heat equally.
Table with temperature graph
The operating mode of boilers depends on the environmental weather.
If we take various objects, for example, a factory premises, multi-storey and a private house, all will have an individual thermal diagram.
In the table we show the temperature dependence diagram residential buildings from outside air:
| Outdoor temperature | Temperature of network water in the supply pipeline | Return water temperature |
| +10 | 70 | 55 |
| +9 | 70 | 54 |
| +8 | 70 | 53 |
| +7 | 70 | 52 |
| +6 | 70 | 51 |
| +5 | 70 | 50 |
| +4 | 70 | 49 |
| +3 | 70 | 48 |
| +2 | 70 | 47 |
| +1 | 70 | 46 |
| 0 | 70 | 45 |
| -1 | 72 | 46 |
| -2 | 74 | 47 |
| -3 | 76 | 48 |
| -4 | 79 | 49 |
| -5 | 81 | 50 |
| -6 | 84 | 51 |
| -7 | 86 | 52 |
| -8 | 89 | 53 |
| -9 | 91 | 54 |
| -10 | 93 | 55 |
| -11 | 96 | 56 |
| -12 | 98 | 57 |
| -13 | 100 | 58 |
| -14 | 103 | 59 |
| -15 | 105 | 60 |
| -16 | 107 | 61 |
| -17 | 110 | 62 |
| -18 | 112 | 63 |
| -19 | 114 | 64 |
| -20 | 116 | 65 |
| -21 | 119 | 66 |
| -22 | 121 | 66 |
| -23 | 123 | 67 |
| -24 | 126 | 68 |
| -25 | 128 | 69 |
| -26 | 130 | 70 |
SNiP
There are certain standards that must be observed in the creation of projects for heating networks and the transportation of hot water to the consumer, where the supply of water steam must be carried out at 400°C, at a pressure of 6.3 Bar. It is recommended that the heat supply from the source be released to the consumer with values of 90/70 °C or 115/70 °C.
Regulatory requirements must be met in compliance with the approved documentation with mandatory approval from the Ministry of Construction of the country.
There are certain patterns according to which the temperature of the coolant in central heating changes. In order to adequately track these fluctuations, there are special graphs.
Causes of temperature changes
To begin with, it is important to understand a few points:
- When weather conditions change, this automatically entails a change in heat loss. When cold weather sets in, to maintain an optimal microclimate in the home, an order of magnitude more thermal energy is spent than during the warm period. In this case, the level of heat consumed is not calculated using the exact temperature of the street air: for this, the so-called. "delta" of the difference between the street and the interior. For example, +25 degrees in an apartment and -20 outside its walls will entail exactly the same heat costs as at +18 and -27, respectively.
- The constancy of the heat flow from the radiators is ensured by the stable temperature of the coolant. As the temperature in the room decreases, there will be a slight rise in the temperature of the radiators: this is facilitated by an increase in the delta between the coolant and the air in the room. In any case, this will not be able to adequately compensate for the increase in heat losses through the walls. This is explained by the setting of restrictions for the lower temperature limit in the home by the current SNiP at +18-22 degrees.
It is most logical to solve the problem of increasing losses by increasing the temperature of the coolant. It is important that its increase occurs in parallel with the decrease in air temperature outside the window: the colder it is there, the greater the heat loss that needs to be replenished. To facilitate orientation in this matter, at some stage it was decided to create special tables for reconciling both values. Based on this, we can say that the temperature graph of the heating system means the derivation of the dependence of the level of water heating in the supply and return pipelines in relation to temperature conditions on the street.
Features of the temperature graph
The above graphs come in two varieties:
- For heat supply networks.
- For the heating system inside the house.
To understand how both of these concepts differ, it is advisable to first understand the features of central heating.
Connection between CHP and heating networks
The purpose of this combination is to communicate the proper heating level to the coolant, followed by its transportation to the place of consumption. Heating pipelines are usually several tens of kilometers long, with a total surface area of tens of thousands of square meters. Although the main networks are subject to careful thermal insulation, it is impossible to do without heat loss.
As you move between the thermal power plant (or boiler room) and the living quarters, some cooling is observed process water. The conclusion itself suggests itself: in order to convey to the consumer an acceptable level of heating of the coolant, it must be supplied inside the heating main from the thermal power plant in the maximum heated state. The rise in temperature is limited by the boiling point. It can be shifted towards higher temperatures if the pressure in the pipes is increased.
The standard pressure indicator in the supply pipe of the heating main is within 7-8 atm. This level, despite the pressure loss during coolant transportation, makes it possible to ensure effective work heating system in buildings up to 16 floors high. In this case, additional pumps are usually not needed.
It is very important that such pressure does not create a danger for the system as a whole: routes, risers, connections, mixing hoses and other components remain operational for a long time. Taking into account a certain margin for the upper limit of the supply temperature, its value is taken as +150 degrees. The most standard temperature curves for supplying coolant to the heating system range between 150/70 - 105/70 (supply and return temperatures).
Features of coolant supply to the heating system
The home heating system is characterized by a number of additional restrictions:
- The maximum heating value of the coolant in the circuit is limited to +95 degrees for two-pipe system and +105 for single pipe system heating. It should be noted that preschool educational institutions are characterized by the presence of more stringent restrictions: there the temperature of the batteries should not rise above +37 degrees. To compensate for this decrease in supply temperature, it is necessary to increase the number of radiator sections. Interior kindergartens located in regions with particularly harsh climatic conditions are literally crammed with batteries.
- It is advisable to achieve a minimum temperature delta of the heating supply schedule between the supply and return pipelines: otherwise, the degree of heating of the radiator sections in the building will have a big difference. To do this, the coolant inside the system must move as quickly as possible. However, there is a danger here: due to the high speed of water circulation inside the heating circuit, its temperature at the exit back into the route will be excessively high. As a result, this can lead to serious disruptions in the operation of the thermal power plant.
To overcome this problem, each house is equipped with one or more elevator modules. Thanks to them, the water flow from the supply pipeline is diluted with a portion from the return line. Using this mixture, it is possible to achieve rapid circulation of significant volumes of coolant without exposing the return pipeline to the danger of excessive heating. The heating system inside the dwellings is set by a separate heating temperature schedule, which takes into account the presence of an elevator. Two-pipe circuits are served by a heating temperature schedule of 95-70, single-pipe circuits - 105-70 (such schemes are almost never found in multi-storey buildings). Read also: “What temperature should be in central heating radiators - norms and standards.”
Influence of climatic zones on outside air temperature
The main factor directly influencing the preparation of a temperature schedule for heating season, is the calculated winter temperature. In the process of compilation, they try to ensure that highest values(95/70 and 105/70) at maximum frosts guaranteed the required SNiP temperature. The outside air temperature for heating calculations is taken from a special table climatic zones.
In this situation, you need to request a recalculation from the resource supply organization (hereinafter referred to as RSO). If you have a common house meter, the heating fee depends on the volume received apartment building coolant.
To influence the RSO, you need, with the participation of a RSO representative, to draw up a two-sided act of verifying the compliance of the coolant temperature with the temperature chart. You also have the right to submit a claim to RSO in connection with improper fulfillment of contractual obligations in terms of excessive temperature.
In accordance with Art. 15 of the Federal Law of July 27, 2010 N 190-FZ “On Heat Supply”, thermal energy consumers purchase thermal energy and coolant from the heat supply organization under a heat supply agreement. Also according to clause 1.1. “Methodological recommendations for regulating relations between RSO and consumers” ( Guidelines Ministry of Energy of Russia dated January 19, 2002) the receipt of thermal energy is carried out on the basis of a heat supply agreement concluded between the RSO and the subscriber.
One of essential conditions heat supply agreement is an indicator of the quality of thermal energy (for thermal energy supplied with network water), provided by RSO - this is the temperature of network water in the supply pipeline in accordance with the temperature schedule, the minimum pressure difference between the supply and return pipelines and limit value pressure in the return pipeline at the boundary of operational responsibility (clause 1.5 of Chapter 1 Heating “Methodological recommendations for regulating relations between the Distribution Region and consumers” of the Ministry of Energy of Russia dated January 19, 2002).
The resource supplying organization is obliged to maintain the temperature of the network water in the supply pipeline at the boundary of operational responsibility in accordance with the temperature schedule attached to the contract.
During periods when the outside air temperature decreases below the design values adopted for the design of heating systems, the temperature of the supply water must be maintained at the level of its value for the design outside air temperature.
The specific schedule depends on the climate, boiler room equipment and technical and economic indicators.
By virtue of clause 6.32 MDK 4-02.2001 “ Standard instructions By technical operation heating networks of municipal heat supply systems" (Order of the Gosstroy of Russia dated December 13, 2000 N 285), the water temperature in the supply line of the water network in accordance with the temperature schedule approved for the heat supply system must be set according to the average outside air temperature over a period of time within 18-24 hours , determined by the heating network manager depending on the length of the networks, climatic conditions and other factors.
According to clause 9.2.1. Order of the Ministry of Energy of Russia dated March 24, 2003 N 115 “On approval of the Rules for the technical operation of thermal power plants”, the deviation of the average daily temperature of water entering the heating systems must be within 3% of the established temperature schedule.
The average daily temperature of the return network water should not exceed the temperature specified by the temperature schedule by more than 5%.
The lower the outside temperature, the higher the temperature in the supply pipe.
Accordingly, the temperature of the return pipeline also changes according to this dependence.
And all systems that consume heat are designed taking these requirements into account.
The temperature schedule determines the operating mode of heating networks, providing central regulation of heat supply.
According to the temperature graph, the temperature of the supply and return water in the heating networks, as well as in the subscriber input, is determined depending on the outside air temperature.
The temperature schedule for regulating the heat load is developed from the conditions of the daily supply of thermal energy for heating, which ensures the need of buildings for thermal energy depending on the outside air temperature, in order to ensure a constant temperature in the premises at a level of at least 18 degrees.
The temperature schedule for regulating the heat load is approved by the heat supply organization (clause 2.3.2 of the MDK 4-03.2001).
According to Art. 539 of the Civil Code of the Russian Federation, under an energy supply agreement, RSO undertakes to supply energy to the subscriber (consumer) through the connected network, and the subscriber undertakes to pay for the received energy, as well as to comply with the regime of its consumption stipulated by the agreement, ensure the safe operation of the energy networks under its control and the serviceability of the devices used by it and equipment related to energy consumption.
In accordance with Art. 542 of the Civil Code of the Russian Federation, the quality of the supplied energy must meet the requirements established in accordance with the legislation Russian Federation, including with mandatory rules, or stipulated by the energy supply agreement.
In case of violation of RSO requirements for energy quality, the subscriber has the right to refuse to pay for such energy.
Based on the provisions of Part 2 of Art. 542 of the Civil Code of the Russian Federation, in order to exercise the right to refuse payment for energy established by this norm, the subscriber must prove the fact of violation of the RSO requirements for the quality of the resource.
In paragraph 2 of Art. 2 of the Federal Law of July 27, 2010 N 190-FZ “On Heat Supply” gives the concept of heat supply quality, which is understood as the totality of heat supply characteristics established by regulatory legal acts of the Russian Federation and (or) the heat supply agreement, including the thermodynamic parameters of the coolant.
The results obtained are compiled into a single table for subsequent construction of the curve:
So, we have three different schemes that can be used as a basis. It would be more correct to calculate the diagram individually for each system. Here we examined the recommended values, without taking into account the climatic features of the region and the characteristics of the building.
To reduce energy consumption, just select a low temperature setting of 70 degrees and uniform heat distribution throughout the heating circuit will be ensured. The boiler should be taken with a power reserve so that the system load does not affect the quality operation of the unit.
Adjustment
Automatic control is provided by the heating regulator.
It includes the following parts:
- Computing and matching panel.
- Actuator on the water supply section.
- Actuator, which performs the function of mixing liquid from the returned liquid (return).
- Boost pump and a sensor on the water supply line.
- Three sensors (on the return line, on the street, inside the building). There may be several of them in the room.
The regulator closes the liquid supply, thereby increasing the value between return and supply to the value specified by the sensors.
To increase the flow, there is a boost pump and a corresponding command from the regulator. The incoming flow is controlled by a "cold bypass". That is, the temperature decreases. Some of the liquid that has circulated along the circuit is sent to the supply.
Sensors collect information and transmit it to control units, resulting in a redistribution of flows that provide a rigid temperature scheme for the heating system.
Sometimes, a computing device is used that combines hot water and heating regulators.
The hot water regulator has a simpler control scheme. The hot water sensor regulates the flow of water with a stable value of 50°C.
Advantages of the regulator:
- The temperature scheme is strictly maintained.
- Elimination of overheating of the liquid.
- Fuel efficiency and energy.
- The consumer, regardless of the distance, receives heat equally.
Table with temperature graph
The operating mode of boilers depends on the environmental weather.
If we take various objects, for example, a factory building, a multi-storey building and a private house, they will all have an individual thermal diagram.
In the table we show the temperature diagram of the dependence of residential buildings on outside air:
| Outdoor temperature | Temperature of network water in the supply pipeline | Return water temperature |
| +10 | 70 | 55 |
| +9 | 70 | 54 |
| +8 | 70 | 53 |
| +7 | 70 | 52 |
| +6 | 70 | 51 |
| +5 | 70 | 50 |
| +4 | 70 | 49 |
| +3 | 70 | 48 |
| +2 | 70 | 47 |
| +1 | 70 | 46 |
| 70 | 45 | |
| -1 | 72 | 46 |
| -2 | 74 | 47 |
| -3 | 76 | 48 |
| -4 | 79 | 49 |
| -5 | 81 | 50 |
| -6 | 84 | 51 |
| -7 | 86 | 52 |
| -8 | 89 | 53 |
| -9 | 91 | 54 |
| -10 | 93 | 55 |
| -11 | 96 | 56 |
| -12 | 98 | 57 |
| -13 | 100 | 58 |
| -14 | 103 | 59 |
| -15 | 105 | 60 |
| -16 | 107 | 61 |
| -17 | 110 | 62 |
| -18 | 112 | 63 |
| -19 | 114 | 64 |
| -20 | 116 | 65 |
| -21 | 119 | 66 |
| -22 | 121 | 66 |
| -23 | 123 | 67 |
| -24 | 126 | 68 |
| -25 | 128 | 69 |
| -26 | 130 | 70 |
There are certain standards that must be observed in the creation of projects for heating networks and the transportation of hot water to the consumer, where the supply of water steam must be carried out at 400°C, at a pressure of 6.3 Bar. It is recommended that the heat supply from the source be released to the consumer with values of 90/70 °C or 115/70 °C.
Regulatory requirements must be met in compliance with the approved documentation with mandatory approval from the Ministry of Construction of the country.
Thermal parameters when entered into the MCD
Question:
What are the parameters thermal regime when entering into MKD?
Answer:
The temperature of the network water in the supply pipelines must correspond to the specified schedule, in accordance with the Rules for the technical operation of thermal power plants, approved by Order of the Ministry of Energy of the Russian Federation dated March 24, 2003 N 115 (hereinafter referred to as Rules N 115).
Graphs of the dependence of coolant temperatures in the supply and return pipelines are called the temperature graph of the heating system.
The heat source temperature graph is a curve that determines what the coolant temperature should be at the actual outside air temperature
In accordance with clause 6.2.58 of Rules No. 115, in the presence of a hot water supply load, the minimum water temperature in the supply pipeline of the network is provided for closed systems heat supply not lower than 70 degrees. WITH; For open systems heating of hot water supply not lower than 60 degrees. WITH.
According to clause 6.2.59 of Rules N 115, the water temperature in the supply line of the water heating network in accordance with the schedule approved for the heat supply system is set according to the average outside air temperature over a period of time within 12 - 24 hours, determined by the heating network manager depending on the length networks, climatic conditions and other factors. In this case, deviations from the set temperature of the water entering the heating network at the heat source are provided for no more than +/- 3%;
By virtue of clause 9.2.1 of Rules No. 115, the deviation of the average daily temperature of water entering the heating, ventilation, air conditioning and hot water supply systems must be within 3% of the established temperature schedule. The average daily temperature of the return network water should not exceed the temperature specified by the temperature schedule by more than 5%.
The pressure and temperature of the coolant supplied to heat-consuming power plants must correspond to the values established by the technological regime (clause 4 of Rules No. 115).
In accordance with clause 107 of the Rules on commercial metering of thermal energy and coolant, approved by Decree of the Government of the Russian Federation of November 18, 2013 N 1034 (hereinafter referred to as Rule N 1034), the following parameters characterizing the thermal and hydraulic mode of the heat supply system of heat supply and heat network organizations are subject to quality control of heat supply:
