Who develops the temperature chart. Heating schedule for quality regulation of heat supply based on the average daily outdoor temperature
The normative water temperature in the heating system depends on the air temperature. Therefore, the temperature schedule 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.
In the calculations, a standard temperature indicator is used. It is calculated according to a special methodology and entered into the governing documentation. This indicator is based on average temperature 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. With an understanding of the ultimate load, it is possible to accurately calculate the characteristics of the required 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 graph of the coolant temperature depending on the outside 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. In single-pipe systems, water heating 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 great pressure due to its wear and tear. 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 used heating appliances. 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 |
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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 the hot coolant is supplied. 7 column - for the return.
The first three columns indicate elevated temperatures - 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.
temperature graph the supply of 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 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 potential danger carries a heated coolant, 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. In public places and at various production facilities, there are usually no special restrictions for them.
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, the maximum temperature of the 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.
Water is heated in network heaters, with selective steam, in peak hot water boilers, after which network water enters the supply line, and then to subscriber heating, ventilation and hot water supply installations.
Heating and ventilation heat loads are uniquely dependent on the outdoor temperature tn.a. Therefore, it is necessary to adjust the heat output in accordance with load changes. You use predominantly central regulation carried out at the CHP, supplemented by local automatic regulators.
With central regulation, it is possible to apply either quantitative regulation, which boils down to a change in the flow of network water in the supply line at a constant temperature, or qualitative regulation, in which the water flow remains constant, but its temperature changes.
A serious drawback of quantitative regulation is the vertical misalignment of heating systems, which means an unequal redistribution of network water across floors. Therefore, quality control is usually used, for which the temperature curves of the heating network for the heating load must be calculated depending on the outside temperature.
The temperature graph for the supply and return lines is characterized by the values of the calculated temperatures in the supply and return lines τ1 and τ2 and the calculated outdoor temperature tn.o. So, the schedule 150-70°C means that at the calculated outdoor temperature tn.o. the maximum (calculated) temperature in the supply line is τ1 = 150 and in the return line τ2 - 70°C. Accordingly, the calculated temperature difference is 150-70 = 80°C. Lower design temperature of the temperature curve 70 °С is determined by the need to heat tap water for the needs of hot water supply up to tg. = 60°C, which is dictated by sanitary standards.
The upper design temperature determines the minimum allowable water pressure in the supply lines, excluding water boiling, and therefore the strength requirements, and can vary in a certain range: 130, 150, 180, 200 °C. An increased temperature schedule (180, 200 ° С) may be required when connecting subscribers according to an independent scheme, which will allow maintaining the usual schedule in the second circuit 150-70 °C. An increase in the design temperature of the network water in the supply line leads to a decrease in the consumption of network water, which reduces the cost of the heating network, but also reduces the generation of electricity from heat consumption. The choice of the temperature schedule for the heat supply system must be confirmed by a feasibility study based on the minimum reduced costs for the CHP and the heat network.
The heat supply of the industrial site of CHPP-2 is carried out according to the temperature schedule of 150/70 °С with a cutoff at 115/70 °С, in connection with which the regulation of the temperature of the network water is automatically carried out only up to the outside air temperature of “-20 °С”. The consumption of network water is too high. The excess of the actual consumption of network water over the calculated one leads to an overexpenditure of electrical energy for pumping the coolant. The temperature and pressure in the return pipe does not match the temperature chart.
The level of heat loads of consumers currently connected to the CHPP is significantly lower than it was envisaged by the project. As a result, CHPP-2 has a thermal capacity reserve exceeding 40% of the installed thermal capacity.
Due to damage to the distribution networks belonging to TMUP TTS, the discharge from the heat supply systems due to the lack of the necessary pressure drop for consumers and the leakage of the heating surfaces of the DHW water heaters, there is an increased consumption of make-up water at the CHP, exceeding the calculated value of 2.2 - 4, 1 time. The pressure in the return heating main also exceeds the calculated value by 1.18-1.34 times.
The above indicates that the heat supply system for external consumers is not regulated and requires adjustment and adjustment.
Dependence of network water temperatures on outdoor air temperature
Table 6.1.
|
Temperature value |
Temperature value |
||||||||||||
|
Outside air |
feed line |
After the elevator |
reverse master |
Outside air |
submitting master |
After the elevator |
In back th mainline ali |
||||||
To maintain a comfortable temperature in the house during the heating period, it is necessary to control the temperature of the coolant in the pipes of heating networks. Employees of the central heating system of residential premises are developing special temperature chart, which depends on weather indicators, climatic features of the region. The temperature schedule may differ in different settlements, and it may also change during the modernization of heating networks.
A schedule is drawn up in the heating network according to a simple principle - the lower the temperature on the street, the higher it should be for the coolant.
This ratio is important basis for work enterprises that provide the city with heat.
For the calculation, an indicator was used, which is based on average daily temperature the five coldest days of the year.
ATTENTION! Compliance temperature regime is important not only for maintaining heat in apartment building. It also allows you to make the consumption of energy resources in the heating system economical, rational.
The graph, which indicates the temperature of the coolant depending on the outside temperature, allows the most optimal way to distribute between consumers apartment building not only heat, but also hot water.
How is heat regulated in the heating system
Heat regulation in an apartment building during the heating period can be carried out in two ways:
- By changing the flow rate of water at a certain constant temperature. This is a quantitative method.
- The change in the temperature of the coolant at a constant flow rate. This is a quality method.
Economical and practical is second option, at which the temperature regime in the room is observed regardless of the weather. The supply of sufficient heat to an apartment building will be stable, even if there is a sharp temperature drop outside.
ATTENTION!. The norm is the temperature of 20-22 degrees in the apartment. If the temperature charts are observed, this norm is maintained throughout the heating period, regardless of weather conditions, wind direction.
When the temperature indicator on the street decreases, data is transmitted to the boiler room and the degree of the coolant automatically increases.
A specific table of the ratio of outdoor temperature and coolant depends on factors such as climate, boiler room equipment, technical and economic indicators.
Reasons for using a temperature chart
The basis for the operation of each boiler house serving residential, administrative and other buildings during the heating period is the temperature chart, which indicates the standards for the coolant indicators, depending on what the actual temperature is. outdoor temperature.
- Drawing up a schedule makes it possible to prepare the heating for a decrease in the temperature outside.
- It is also energy saving.
ATTENTION! In order to control the temperature of the heat carrier and be eligible for recalculation due to non-compliance with the thermal regime, the heat sensor must be installed in the central heating system. Meters must be checked annually.
Modern construction companies can increase the cost of housing through the use of expensive energy-saving technologies in the construction of multi-apartment buildings.
Despite the change construction technologies, the use of new materials for the insulation of walls and other surfaces of the building, compliance with the norms of the temperature of the coolant in the heating system - best way maintain comfortable living conditions.
Features of calculating the internal temperature in different rooms
The rules provide for maintaining the temperature for living quarters at 18˚С, but there are some nuances in this matter.
- For angular rooms of a residential building coolant must provide a temperature of 20 ° C.
- Optimum temperature indicator for the bathroom - 25˚С.
- It is important to know how many degrees should be according to the standards in rooms intended for children. Indicator set from 18˚С to 23˚С. If this Children's swimming pool, you need to maintain the temperature at 30 ° C.
- Minimum temperature, admissible in schools - 21˚С.
- In institutions where mass cultural events are held according to the standards, maximum temperature 21˚С, but the indicator should not fall below the figure 16˚С.
To increase the temperature in the premises during a sharp cold snap or a strong north wind, the boiler house workers increase the degree of energy supply for heating networks.
The heat transfer of the batteries is affected by the outside temperature, the type of heating system, the direction of the coolant flow, the state of utility networks, the type of heater, the role of which can be played by both a radiator and a convector.
ATTENTION! The temperature delta between the supply to the radiator and the return should not be significant. Otherwise it will feel big difference coolant in different rooms and even apartment buildings.
The main factor, however, is the weather., which is why measuring outdoor air to maintain a temperature graph is a top priority.
If it is cold outside up to 20˚С, the coolant in the radiator should have an indicator of 67-77˚С, while the norm for the return is 70˚С.
If the street temperature is zero, the norm for the coolant is 40-45˚С, and for the return - 35-38˚С. It should be noted that the temperature difference between supply and return is not large.
Why does the consumer need to know the norms for the supply of coolant?
Payment utilities in the heating column should depend on what temperature the supplier provides in the apartment.
Table of the temperature graph, according to which optimal performance boiler, shows at what temperature of the environment and by how much the boiler room should increase the degree of energy for heat sources in the house.
IMPORTANT! If the parameters of the temperature schedule are not observed, the consumer may demand a recalculation for utilities.
To measure the coolant indicator, it is necessary to drain some water from the radiator and check its degree of heat. Also successfully used thermal sensors, heat meters that can be installed at home.
The sensor is a mandatory equipment for both city boiler houses and ITPs (individual heating points).
Without such devices, it is impossible to make the operation of the heating system economical and productive. Coolant measurement is also carried out in hot water systems.
Useful video
Looking through the statistics of visits to our blog, I noticed that search phrases such as, for example, appear very often “What should be the temperature of the coolant at minus 5 outside?”. Decided to post the old one. schedule quality regulation heat supply according to the average daily outdoor temperature. I want to warn those who, on the basis of these figures, will try to sort out relations with the housing department or heating networks: the heating schedules for each individual settlement are different (I wrote about this in an article). Work on this schedule heating network in Ufa (Bashkiria).
I also want to draw attention to the fact that regulation occurs according to average daily outside temperature, so if, for example, outside at night minus 15 degrees, and during the day minus 5, then the coolant temperature will be maintained in accordance with the schedule minus 10 o C.
As a rule, the following temperature charts are used: 150/70 , 130/70 , 115/70 , 105/70 , 95/70 . The schedule is selected depending on the specific local conditions. House heating systems operate according to schedules 105/70 and 95/70. According to schedules 150, 130 and 115/70, main heat networks operate.
Let's look at an example of how to use the chart. Suppose the temperature outside is minus 10 degrees. Heating networks operate according to the temperature schedule 130/70 , which means at -10 o С the temperature of the heat carrier in the supply pipeline of the heating network must be 85,6 degrees, in the supply pipeline of the heating system - 70.8 o C with a schedule of 105/70 or 65.3 about C on a 95/70 schedule. The temperature of the water after the heating system must be 51,7 about S.
As a rule, the temperature values in the supply pipeline of heat networks are rounded off when setting the heat source. For example, according to the schedule, it should be 85.6 ° C, and 87 degrees are set at the CHP or boiler house.
| Temperature outdoor air Tnv, o C |
Temperature of network water in the supply pipeline T1, about C |
Water temperature in the supply pipe of the heating system T3, about C |
Water temperature after heating system T2, about C |
|||
|---|---|---|---|---|---|---|
| 150 | 130 | 115 | 105 | 95 | ||
| 8 | 53,2 | 50,2 | 46,4 | 43,4 | 41,2 | 35,8 |
| 7 | 55,7 | 52,3 | 48,2 | 45,0 | 42,7 | 36,8 |
| 6 | 58,1 | 54,4 | 50,0 | 46,6 | 44,1 | 37,7 |
| 5 | 60,5 | 56,5 | 51,8 | 48,2 | 45,5 | 38,7 |
| 4 | 62,9 | 58,5 | 53,5 | 49,8 | 46,9 | 39,6 |
| 3 | 65,3 | 60,5 | 55,3 | 51,4 | 48,3 | 40,6 |
| 2 | 67,7 | 62,6 | 57,0 | 52,9 | 49,7 | 41,5 |
| 1 | 70,0 | 64,5 | 58,8 | 54,5 | 51,0 | 42,4 |
| 0 | 72,4 | 66,5 | 60,5 | 56,0 | 52,4 | 43,3 |
| -1 | 74,7 | 68,5 | 62,2 | 57,5 | 53,7 | 44,2 |
| -2 | 77,0 | 70,4 | 63,8 | 59,0 | 55,0 | 45,0 |
| -3 | 79,3 | 72,4 | 65,5 | 60,5 | 56,3 | 45,9 |
| -4 | 81,6 | 74,3 | 67,2 | 62,0 | 57,6 | 46,7 |
| -5 | 83,9 | 76,2 | 68,8 | 63,5 | 58,9 | 47,6 |
| -6 | 86,2 | 78,1 | 70,4 | 65,0 | 60,2 | 48,4 |
| -7 | 88,5 | 80,0 | 72,1 | 66,4 | 61,5 | 49,2 |
| -8 | 90,8 | 81,9 | 73,7 | 67,9 | 62,8 | 50,1 |
| -9 | 93,0 | 83,8 | 75,3 | 69,3 | 64,0 | 50,9 |
| -10 | 95,3 | 85,6 | 76,9 | 70,8 | 65,3 | 51,7 |
| -11 | 97,6 | 87,5 | 78,5 | 72,2 | 66,6 | 52,5 |
| -12 | 99,8 | 89,3 | 80,1 | 73,6 | 67,8 | 53,3 |
| -13 | 102,0 | 91,2 | 81,7 | 75,0 | 69,0 | 54,0 |
| -14 | 104,3 | 93,0 | 83,3 | 76,4 | 70,3 | 54,8 |
| -15 | 106,5 | 94,8 | 84,8 | 77,9 | 71,5 | 55,6 |
| -16 | 108,7 | 96,6 | 86,4 | 79,3 | 72,7 | 56,3 |
| -17 | 110,9 | 98,4 | 87,9 | 80,7 | 73,9 | 57,1 |
| -18 | 113,1 | 100,2 | 89,5 | 82,0 | 75,1 | 57,9 |
| -19 | 115,3 | 102,0 | 91,0 | 83,4 | 76,3 | 58,6 |
| -20 | 117,5 | 103,8 | 92,6 | 84,8 | 77,5 | 59,4 |
| -21 | 119,7 | 105,6 | 94,1 | 86,2 | 78,7 | 60,1 |
| -22 | 121,9 | 107,4 | 95,6 | 87,6 | 79,9 | 60,8 |
| -23 | 124,1 | 109,2 | 97,1 | 88,9 | 81,1 | 61,6 |
| -24 | 126,3 | 110,9 | 98,6 | 90,3 | 82,3 | 62,3 |
| -25 | 128,5 | 112,7 | 100,2 | 91,6 | 83,5 | 63,0 |
| -26 | 130,6 | 114,4 | 101,7 | 93,0 | 84,6 | 63,7 |
| -27 | 132,8 | 116,2 | 103,2 | 94,3 | 85,8 | 64,4 |
| -28 | 135,0 | 117,9 | 104,7 | 95,7 | 87,0 | 65,1 |
| -29 | 137,1 | 119,7 | 106,1 | 97,0 | 88,1 | 65,8 |
| -30 | 139,3 | 121,4 | 107,6 | 98,4 | 89,3 | 66,5 |
| -31 | 141,4 | 123,1 | 109,1 | 99,7 | 90,4 | 67,2 |
| -32 | 143,6 | 124,9 | 110,6 | 101,0 | 94,6 | 67,9 |
| -33 | 145,7 | 126,6 | 112,1 | 102,4 | 92,7 | 68,6 |
| -34 | 147,9 | 128,3 | 113,5 | 103,7 | 93,9 | 69,3 |
| -35 | 150,0 | 130,0 | 115,0 | 105,0 | 95,0 | 70,0 |
Please do not focus on the diagram at the beginning of the post - it does not correspond to the data from the table.
Calculation of the temperature graph
The method for calculating the temperature graph is described in the reference book (Chapter 4, p. 4.4, p. 153,).
This is a rather laborious and lengthy process, since several values must be calculated for each outdoor temperature: T 1, T 3, T 2, etc.
To our joy, we have a computer and a MS Excel spreadsheet. A colleague at work shared with me a ready-made table for calculating the temperature graph. She was once made by his wife, who worked as an engineer for a group of regimes in thermal networks.
In order for Excel to calculate and build a graph, it is enough to enter several initial values:
- design temperature in the supply pipeline of the heating network T 1
- design temperature in the return pipeline of the heating network T 2
- design temperature in the supply pipe of the heating system T 3
- Outside temperature T n.v.
- Indoor temperature T v.p.
- coefficient " n» (it is usually not changed and is equal to 0.25)
- Minimum and maximum cut of the temperature graph Cut min, Cut max.
All. nothing more is required of you. The results of the calculations will be in the first table of the sheet. It is highlighted in bold.
The charts will also be rebuilt for the new values.
The table also considers the temperature of direct network water, taking into account wind speed.
There are a number of regularities on the basis of which the change in the temperature of the coolant in central heating. To track fluctuations, there are special graphs called temperature graphs. What they are and what they are for, you need to understand in more detail.
What is a temperature chart and its purpose
The temperature curve of the heating system is the dependence of the temperature of the coolant, which is water, on the temperature indicator of the outside air.
The main indicators of the considered graph are two values:
- The temperature of the heat carrier, that is, the heated water that is supplied to the heating system for heating residential premises.
- Temperature readings of outdoor air.
The lower the ambient temperature, the more it is required to heat the coolant that is supplied to the heating system. The considered schedule is built when designing heating systems for buildings. It depends on factors such as size. heating devices, flow rate of the coolant in the system, as well as the diameter of the pipelines through which the coolant is transferred.
The designation of the temperature graph is carried out using two numbers, which are 90-70 degrees. What does this mean? These figures characterize the temperature of the coolant, which must be supplied to the consumer and returned back. To create a comfortable indoor environment in winter period at an outdoor temperature of -20 degrees, you need to supply a coolant with a value of 90 degrees Celsius to the system, and return with a value of 70 degrees.
The temperature graph allows you to determine the overestimated or underestimated flow of the coolant. If the value of the temperature of the returned coolant is too high, this will indicate a high flow rate. If the value is underestimated, then this indicates a deficit in consumption.
The schedule of 95-70 degrees for the heating system was adopted in the last century for buildings up to 10 floors. If the number of storeys of the building exceeds 10 floors, then the values of 105-70 degrees were taken. Modern standards for heat supply for each new building are different, and are often adopted at the discretion of the designer. Modern standards for insulated houses are 80-60 degrees, and for buildings without insulation 90-70.
Why temperature fluctuations occur
The causes of temperature changes are determined by the following factors:
- When weather conditions change, the heat loss automatically changes. When cold weather sets in, to ensure an optimal microclimate in apartment buildings, it is necessary to spend more heat energy than with warming. The level of consumed heat loss is calculated by the value of "delta", which is the difference between the street and indoors.
- permanence heat flow from batteries is provided with a stable value of the coolant temperature. As soon as the temperature drops, the apartment radiators will get warmer. This phenomenon is facilitated by an increase in the "delta" between the coolant and the air in the room.
An increase in heat carrier losses must be carried out in parallel with a decrease in the air temperature outside the window. The colder it is outside the window, the higher the temperature of the water in the heating pipes should be. To facilitate the calculation processes, a corresponding table was adopted.
What is a temperature chart
The temperature graph for the supply of coolant to heating systems is a table that lists the values of the coolant temperature depending on the outside temperature.
The generalized graph of water temperature in the heating system is as follows:
The formula for calculating the temperature graph is as follows:
- To determine the coolant supply temperature: Т1=tin+∆хQ(0.8)+(β-0.5хUP)хQ.
- To determine the return flow temperature, the following formula is used: T2=tin+∆xQ(0.8)-0.5xUPxQ.
In the presented formulas:
Q is the relative heating load.
∆ is the temperature difference of the coolant supply.
β is the temperature difference in the forward and reverse supply.
UP is the difference between the water temperature at the inlet and outlet of the heater.
Graphs are of two types:
- For heating networks.
- For apartment buildings.
To understand the details, consider the features of the functioning of central heating.
CHP and heat networks: what is the relationship
The purpose of thermal power plants and heating networks is to heat the coolant to a certain value, and then transport it to the place of consumption. At the same time, it is important to take into account the losses on the heating main, the length of which is usually 10 kilometers. Despite the fact that all water supply pipes are thermally insulated, it is almost impossible to do without heat loss.
When the coolant moves from a thermal power plant or simply a boiler house to a consumer (an apartment building), then a certain percentage of water cooling is observed. To ensure the supply of coolant to the consumer in the required normalized value, it is required to supply it from the boiler house in the most heated state. However, it is impossible to increase the temperature above 100 degrees, since it is limited by the boiling point. However, it can be shifted in the direction of increasing the temperature value by increasing the pressure in the heating system.
The pressure in the pipes according to the standard is 7-8 atmospheres, however, when the coolant is supplied, a pressure loss also occurs. However, despite the pressure loss, a value of 7-8 atmospheres allows you to provide efficient work heating systems even in 16-storey buildings.
It is interesting! The pressure in the heating system of 7-8 atmospheres is not dangerous for the network itself. All structural elements remain operational in normal mode.
Taking into account the reserve of the upper temperature threshold, its value is 150 degrees. The minimum supply temperature at minus values outside the window is not lower than 9 degrees. The return temperature is usually 70 degrees.
How is the coolant supplied to the heating system
The following limitations are characteristic of the house heating system:
- The maximum heating indicator is determined by the limited value of +95 degrees for a two-pipe system, as well as 105 degrees for a one-pipe network. Stricter restrictions apply in preschools. The value of the water temperature in the battery should not rise above 37 degrees. To compensate for the low temperature value, additional sections of radiators are built up. Kindergartens, which are located directly in regions with severe climatic zones, are equipped with a large number of radiators with a numerous number of sections.
- The best option is to achieve the minimum value of "delta", which represents the difference between the supply and output temperatures of the coolant. If this value is not achieved, then the degree of heating of the radiators will have a high difference. To reduce the difference, it is necessary to increase the speed of the coolant. However, even with an increase in the speed of movement of the coolant, a significant drawback arises, which is due to the fact that water will return back to the CHPP with excessive high temperature. This phenomenon can lead to the fact that there will be violations of the CHP.
To get rid of such a problem, elevator modules should be installed in each apartment building. By means of such devices, a portion of the supply water with the return is diluted. This mixture will allow you to get accelerated circulation, thereby eliminating the possibility of excessive overheating of the return pipeline.
If an elevator is installed in a private house, then the accounting for the heating system is set using an individual temperature graph. For two-pipe systems heating of a private house is characterized by modes of 95-70, and for single-pipe - 105-70 degrees.
How climate zones affect air temperature
The main factor that is taken into account when calculating the temperature graph is presented in the form of an estimated temperature in winter. When calculating the heating, the outdoor temperature is taken from a special table for climatic zones.
table temperature coolant should be drawn up so that its maximum value satisfies the SNiP temperature in residential premises. For example, we use the following data:
- As heating devices, radiators are used, which provide the supply of coolant from the bottom up.
- The type of heating of apartments is two-pipe, equipped with a parking piping.
- The calculated values of the outdoor temperature are -15 degrees.
This gives us the following information:
- Heating will be started when the average daily temperature does not exceed +10 degrees for 3-5 days. The coolant will be supplied with a value of 30 degrees, and the return will be equal to 25 degrees.
- When the temperature drops to 0 degrees, the coolant value rises to 57 degrees, and the return flow will be 46 degrees.
- At -15, water will be supplied at a temperature of 95 degrees, and the return is 70 degrees.
It is interesting! When determining the average daily temperature, information is taken from both daytime thermometer readings and nighttime measurements.
How to regulate the temperature
CHP employees are responsible for the parameters of the heating mains, but the control of networks inside residential buildings is carried out by employees of the housing office or management companies. Often, the housing office receives complaints from residents that it is cold in the apartments. To normalize the system parameters, you will need to carry out the following activities:
- Increasing the diameter of the nozzle or installing an elevator with adjustable nozzle. If there is an underestimated value of the liquid temperature in the return, then this problem can be solved by increasing the diameter of the elevator nozzle. To do this, close the valves and valves, and then remove the module. The nozzle is enlarged by drilling it by 0.5-1 mm. After completing the procedure, the device returns to its place, after which the procedure for bleeding air from the system is necessarily carried out.
- Shut off the suction. To avoid the threat of the jumper performing the suction function, it is muted. To perform this procedure, a steel pancake is used, the thickness of which should be about 1 mm. This method of temperature control belongs to the category of emergency options, since during its implementation the occurrence of a temperature jump of up to +130 degrees is not excluded.
- Variation regulation. You can solve the problem by adjusting the drops with an elevator valve. The essence of this correction method is to redirect the DHW to the supply pipe. A pressure gauge is screwed into the return pipe, after which the valve of the return pipeline is closed. When opening the valve, it is necessary to carry out a reconciliation with the readings of the manometer.
If you install a conventional valve, it will stop and freeze the system. To reduce the difference, you need to increase the return pressure to a value of 0.2 atm / day. What temperature should be in the batteries can be found on the basis of the temperature graph. Knowing its value, you can check to make sure it matches the temperature regime.
In conclusion, it should be noted that the options for damping the suction and regulating the drops are used exclusively in the development of critical situations. Knowing such a minimum of information, you can contact the housing office or thermal power plant with complaints and wishes about inappropriate coolant standards in the system.
