Temperature chart of the heat supply organization. Heating schedule for quality regulation of heat supply based on the average daily outdoor temperature
After installing the heating system, it is necessary to adjust temperature regime. This procedure must be carried out in accordance with existing standards.
The requirements for the temperature of the coolant are set out in the regulatory documents that establish the design, installation and use engineering systems residential and public buildings. They are described in the State building codes and regulations:
- DBN (B. 2.5-39 Heat networks);
- SNiP 2.04.05 "Heating, ventilation and air conditioning".
For the calculated temperature of the water in the supply, the figure is taken that is equal to the temperature of the water at the outlet of the boiler, according to its passport data.
For individual heating to decide what should be the temperature of the coolant, should be taking into account such factors:
- Start and end of the heating season average daily temperature outside +8 °C for 3 days;
- The average temperature inside heated premises of housing and communal and public importance should be 20 ° C, and for industrial buildings 16 ° C;
- The average design temperature must comply with the requirements of DBN V.2.2-10, DBN V.2.2.-4, DSanPiN 5.5.2.008, SP No. 3231-85.
According to SNiP 2.04.05 "Heating, ventilation and air conditioning" (clause 3.20), the coolant limit values are as follows:
Depending on the external factors, the water temperature in the heating system can be from 30 to 90 °C. When heated above 90 ° C, dust begins to decompose and paintwork. For these reasons sanitary norms prohibit more heating.
For calculation optimal performance special charts and tables can be used that define the norms depending on the season:
- With an average value outside the window of 0 °С, the supply for radiators with different wiring is set at a level of 40 to 45 °С, and the return temperature is from 35 to 38 °С;
- At -20 °С, the supply is heated from 67 to 77 °С, while the return rate should be from 53 to 55 °С;
- At -40 ° C outside the window for all heating devices set the maximum allowed values. At the supply it is from 95 to 105 ° C, and at the return - 70 ° C.
Optimal values in an individual heating system
H2_2Heating system helps to avoid many of the problems that arise with centralized network, a optimum temperature The coolant can be adjusted according to the season. In the case of individual heating, the concept of norm includes the heat transfer of a heating device per unit area of the room where this device is located. The thermal regime in this situation is provided design features heating appliances.
It is important to ensure that the heat carrier in the network does not cool below 70 ° C. 80 °C is considered optimal. FROM gas boiler it is easier to control heating, because manufacturers limit the possibility of heating the coolant to 90 ° C. Using sensors to adjust the gas supply, the heating of the coolant can be controlled.
It is a little more difficult with solid fuel devices, they do not regulate the heating of the liquid, and can easily turn it into steam. And it is impossible to reduce the heat from coal or wood by turning the knob in such a situation. At the same time, the control of heating of the coolant is rather conditional with high errors and is performed by rotary thermostats and mechanical dampers.
Electric boilers allow you to smoothly adjust the heating of the coolant from 30 to 90 ° C. They are equipped with an excellent overheating protection system.
One-pipe and two-pipe lines
The design features of a single-pipe and two-pipe heating network determine different norms for heating the coolant.
For example, for a single-pipe line, the maximum rate is 105 ° C, and for a two-pipe line - 95 ° C, while the difference between the return and supply should be, respectively: 105 - 70 ° C and 95 - 70 ° C.
Matching the temperature of the heat carrier and the boiler
Regulators help to coordinate the temperature of the coolant and the boiler. These are devices that create automatic control and correction of the return and supply temperatures.
The return temperature depends on the amount of liquid passing through it. The regulators cover the liquid supply and increase the difference between the return and supply to the level that is needed, and the necessary pointers are installed on the sensor.
If it is necessary to increase the flow, then a boost pump can be added to the network, which is controlled by a regulator. To reduce the heating of the supply, a “cold start” is used: that part of the liquid that has passed through the network is again transferred from the return to the inlet.
The regulator redistributes the supply and return flows according to the data taken by the sensor, and ensures strict temperature norms heating networks.
Ways to reduce heat loss
The above information will help to be used for the correct calculation of the coolant temperature norm and will tell you how to determine the situations when you need to use the regulator.
But it is important to remember that the temperature in the room is affected not only by the temperature of the coolant, outdoor air and wind strength. The degree of insulation of the facade, doors and windows in the house should also be taken into account.
To reduce the heat loss of housing, you need to worry about its maximum thermal insulation. Insulated walls, sealed doors, metal-plastic windows will help reduce heat leakage. It will also reduce heating costs.
There are certain patterns by which the temperature of the coolant in central heating changes. In order to adequately trace these fluctuations, there are special graphs.
Reasons for temperature changes
To begin with, it is important to understand a few points:
- When they change weather, this automatically entails a change in heat loss. With the onset of cold weather to maintain in the home optimal microclimate an order of magnitude more heat energy is spent than in the warm period. At the same time, the level of consumed heat is not calculated by the exact temperature of the outdoor 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.
- permanence heat flow from heating batteries is provided with a stable coolant temperature. With a decrease in the temperature in the room, a certain rise in the temperature of the radiators will be observed: 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 loss through the walls. This is explained by the setting of restrictions for the lower temperature limit in the dwelling by the current SNiP at the level of + 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, the big losses heat 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 the temperature regime on the street.
Features of the temperature graph
The above charts come in two varieties:
- For heating 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 the operation of centralized heating.
Link between CHP and heating networks
The purpose of this combination is to communicate the proper level of heating to the coolant, with its subsequent transportation to the place of consumption. Heating mains usually have a length of several tens of kilometers, with total area surfaces in the tens of thousands square meters. Although the main networks are subjected to thorough thermal insulation, it is impossible to do without heat losses.
In the direction of travel between the CHP (or boiler house) and residential premises, there is some cooling technical 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 CHP in the most heated state. The temperature swing is limited by the boiling point. It can be shifted in the direction of increasing temperature if the pressure in the pipes is increased.
The standard pressure indicator in the supply pipe of the heating main is in the range of 7-8 atm. This level, despite the pressure loss during the transportation of the coolant, makes it possible to ensure efficient operation 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 pose a danger to the system as a whole: routes, risers, lines, mixing hoses and other components remain operational. long time. Given a certain margin for the upper limit of the supply temperature, its value is taken as +150 degrees. The passage of the most standard temperature curves for the supply of coolant to the heating system takes place between 150/70 - 105/70 (supply and return temperatures).
Features of the supply of coolant to the heating system
The house heating system is characterized by a number of additional restrictions:
- The value of the highest heating of the coolant in the circuit is limited to +95 degrees for a 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, the number of radiator sections has to be increased. Interior spaces kindergartens located in regions with particularly harsh climatic conditions are literally crammed with batteries.
- It is desirable 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 large 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 outlet back to the route will be unnecessarily high. As a result, this can lead to serious violations in the operation of the CHP.
Influence of climatic zones on outdoor temperature
The main factor that directly affects the preparation of the temperature schedule for the heating season is the estimated winter temperature. In the course of compilation, they try to ensure that highest values(95/70 and 105/70) at maximum frosts guaranteed the required SNiP temperature. The outdoor temperature for calculating heating is taken from a special table climatic zones.
Adjustment Features
The parameters of thermal routes are in the area of responsibility of the management of CHPPs and heating networks. At the same time, ZhEK employees are responsible for the network parameters inside the building. Basically, residents' complaints about the cold relate to downward deviations. Situations are much less common when measurements inside thermal units indicate an increased return temperature.
There are several ways to normalize system parameters that you can implement yourself:
- Nozzle reaming. The problem of lowering the temperature of the liquid in the return can be solved by expanding the elevator nozzle. To do this, you need to close all the valves and valves on the elevator. After that, the module is removed, its nozzle is pulled out and reamed by 0.5-1 mm. After assembling the elevator, it is launched to bleed air in the reverse order. Paronite seals on the flanges are recommended to be replaced with rubber ones: they are made according to the size of the flange from the automobile chamber.
- Suction suppression. In extreme cases (with the onset of ultra-low frosts), the nozzle can be dismantled altogether. In this case, there is a threat that the suction will begin to perform the function of a jumper: in order to prevent this, it is jammed. For this, a steel pancake with a thickness of 1 mm is used. This method is an emergency, because this can provoke a jump in battery temperature up to +130 degrees.
- Delta control. A temporary way to solve the problem of temperature rise is to correct the differential with an elevator valve. To do this, it is necessary to redirect the DHW to the supply pipe: the return pipe is equipped with a pressure gauge. The inlet valve of the return pipeline is completely closed. Next, you need to gradually open the valve, constantly checking your actions with the readings of the pressure gauge.
Just a closed valve can cause a shutdown and defrosting of the circuit. The decrease in the difference is achieved due to an increase in the return pressure (0.2 atm./day). The temperature in the system must be checked every day: it must correspond to the heating temperature curve.
The supply of heat to the room is associated with the simplest temperature graph. The temperature values of the water supplied from the boiler room do not change indoors. They have standard values and range from +70ºС to +95ºС. Such temperature graph heating system is the most demanded.
Adjusting the air temperature in the house
Not everywhere in the country there is centralized heating, so many residents install independent systems. Their temperature graph differs from the first option. In this case, the temperature indicators are significantly reduced. They depend on the efficiency of modern heating boilers.
If the temperature reaches +35ºС, the boiler will work on maximum power. It depends on the heating element, where thermal energy can be taken in by exhaust gases. If the temperature values are greater than + 70 ºС, then the boiler performance drops. In that case, in his technical specification 100% efficiency is indicated.
Temperature chart and calculation
How the graph will look depends on the outside temperature. The greater the negative value of the outside temperature, the greater the heat loss. Many do not know where to take this indicator. This temperature is specified in the regulatory documents. The temperature of the coldest five-day period is taken as the calculated value, and the lowest value over the past 50 years is taken.
Graph of outside and inside temperature The graph shows the relationship between outside and inside temperatures. Let's say the outside temperature is -17ºС. Drawing a line up to the intersection with t2, we get a point characterizing the temperature of the water in the heating system.
Thanks to the temperature schedule, it is possible to prepare the heating system even under the most severe conditions. It also reduces the material costs of installing a heating system. If we consider this factor from the point of view of mass construction, the savings are significant.
inside premises depends from temperature coolant, a also others factors:
- Outside air temperature. The smaller it is, the more negatively it affects heating;
- Wind. When a strong wind occurs, heat loss increases;
- The indoor temperature depends on the thermal insulation of the structural elements of the building.
Over the past 5 years, the principles of construction have changed. Builders increase the value of a home by insulating elements. As a rule, this applies to basements, roofs, foundations. These costly measures subsequently allow residents to save on the heating system.
Heating temperature chart The graph shows the dependence of the temperature of the outdoor and indoor air. The lower the outdoor temperature, the higher the temperature of the heating medium in the system.
The temperature schedule is developed for each city during heating period. In small settlements, a temperature chart of the boiler house is drawn up, which provides required amount coolant to the consumer.
Change temperature schedule can several ways:
- quantitative - characterized by a change in the flow rate of the coolant supplied to the heating system;
- high-quality - consists in regulating the temperature of the coolant before being supplied to the premises;
- temporary - a discrete method of supplying water to the system.
The temperature schedule is a heating pipeline schedule that distributes the heating load and is regulated by centralized systems. There is also increased schedule, it is created for a closed heating system, that is, to ensure the supply of hot coolant to the connected objects. When using an open system, it is necessary to adjust the temperature graph, since the coolant is consumed not only for heating, but also for domestic water consumption.
The calculation of the temperature graph is made according to simple method. Hto build it needed initial temperature air data:
- outdoor;
- in room;
- in the supply and return pipelines;
- at the exit of the building.
In addition, you should know the nominal heat load. All other coefficients are normalized by reference documentation. The calculation of the system is made for any temperature graph, depending on the purpose of the room. For example, for large industrial and civil facilities, a schedule of 150/70, 130/70, 115/70 is drawn up. For residential buildings, this figure is 105/70 and 95/70. The first indicator shows the temperature on the supply, and the second - on the return. The results of the calculations are entered in a special table, which shows the temperature at certain points of the heating system, depending on the outside air temperature.
The main factor in calculating the temperature graph is the outside air temperature. The calculation table should be drawn up so that the maximum values of the temperature of the coolant in the heating system (schedule 95/70) provide heating of the room. The room temperatures are provided normative documents.
heating appliances
Temperature of heating devices The main indicator is the temperature of the heating devices. The ideal temperature curve for heating is 90/70ºС. It is impossible to achieve such an indicator, since the temperature inside the room should not be the same. It is determined depending on the purpose of the room.
In accordance with the standards, the temperature in the corner living room is +20ºС, in the rest - +18ºС; in the bathroom - + 25ºС. If the outside air temperature is -30ºС, then the indicators increase by 2ºС.
Except Togo, exists norms for others types premises:
- in rooms where children are located - + 18ºС to + 23ºС;
- children's educational institutions - + 21ºС;
- in cultural institutions with mass attendance - +16ºС to +21ºС.
This area of temperature values is compiled for all types of premises. It depends on the movements performed inside the room: the more of them, the lower the air temperature. For example, in sports facilities people move a lot, so the temperature is only +18ºС.
Air temperature in the room Exist certain factors, from which depends temperature heating appliances:
- Outside air temperature;
- Type of heating system and temperature difference: for a single-pipe system - + 105ºС, and for a single-pipe system - + 95ºС. Accordingly, the differences in for the first region are 105/70ºС, and for the second - 95/70ºС;
- The direction of the coolant supply to the heating devices. At the top supply, the difference should be 2 ºС, at the bottom - 3ºС;
- Type of heating devices: heat transfers are different, so the temperature graph will be different.
First of all, the temperature of the coolant depends on the outside air. For example, the outside temperature is 0°C. At the same time, the temperature regime in the radiators should be equal to 40-45ºС on the supply, and 38ºС on the return. When the air temperature is below zero, for example, -20ºС, these indicators change. In this case, the flow temperature becomes 77/55ºC. If the temperature indicator reaches -40ºС, then the indicators become standard, that is, at the supply + 95/105ºС, and at the return - + 70ºС.
Additional options
In order for a certain temperature of the coolant to reach the consumer, it is necessary to monitor the state of the outside air. For example, if it is -40ºС, the boiler room should supply hot water with an indicator of + 130ºС. Along the way, the coolant loses heat, but still the temperature remains high when it enters the apartments. The optimal value is + 95ºС. To do this, an elevator assembly is installed in the basements, which serves for mixing hot water from the boiler room and the coolant from the return pipeline.
Several institutions are responsible for the heating main. The boiler house monitors the supply of hot coolant to the heating system, and the state of the pipelines is monitored by the city heating networks. The ZHEK is responsible for the elevator element. Therefore, in order to solve the problem of supplying coolant to a new house, it is necessary to contact different offices.
Installation of heating devices is carried out in accordance with regulatory documents. If the owner himself replaces the battery, then he is responsible for the functioning of the heating system and changing the temperature regime.
Adjustment methods
Dismantling elevator node If the boiler room is responsible for the parameters of the coolant leaving the warm point, then the employees of the housing office should be responsible for the temperature inside the room. Many tenants complain about the cold in the apartments. This is due to the deviation of the temperature graph. In rare cases, it happens that the temperature rises by a certain value.
Heating parameters can be adjusted in three ways:
- Nozzle reaming.
If the temperature of the coolant at the supply and return is significantly underestimated, then it is necessary to increase the diameter of the elevator nozzle. Thus, more liquid will pass through it.
How to do it? To begin with, shut-off valves are closed (house valves and cranes at the elevator unit). Next, the elevator and nozzle are removed. Then it is drilled out by 0.5-2 mm, depending on how much it is necessary to increase the temperature of the coolant. After these procedures, the elevator is mounted in its original place and put into operation.
To ensure sufficient tightness of the flange connection, it is necessary to replace the paronite gaskets with rubber ones.
- Suction dampening.
At extreme cold when there is a problem of freezing of the heating system in the apartment, the nozzle can be completely removed. In this case, the suction can become a jumper. To do this, it is necessary to muffle it with a steel pancake, 1 mm thick. Such a process is carried out only in critical situations, since the temperature in pipelines and heaters will reach 130ºС.
- Drop adjustment.
In the middle of the heating period, a significant increase in temperature can occur. Therefore, it is necessary to regulate it using a special valve on the elevator. To do this, the supply of hot coolant is switched to the supply pipeline. A manometer is mounted on the return. Adjustment occurs by closing the valve on the supply pipeline. Next, the valve opens slightly, and the pressure should be monitored using a pressure gauge. If you just open it, then there will be a drawdown of the cheeks. That is, an increase in the pressure drop occurs in the return pipeline. Every day, the indicator increases by 0.2 atmosphere, and the temperature in the heating system must be constantly monitored.
Heat supply. Video
How is the heat supply of private and apartment buildings can be found in the video below.
When drawing up a temperature schedule for heating, it is necessary to take into account various factors. This list includes not only structural elements building, but the outside temperature, as well as the type of heating system.
In contact with
Looking through the statistics of visiting our blog, I noticed that search phrases such as, for example, “what should be the temperature of the coolant at minus 5 outside?” appear very often. Decided to post the old chart quality regulation heat supply according to the average daily temperature of the outside air. 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 the article on regulating the temperature of the coolant). Thermal networks in Ufa (Bashkiria) operate according to this schedule.
I also want to draw attention to the fact that regulation takes place according to the average daily outdoor temperature, so if, for example, it is minus 15 degrees outside at night and minus 5 during the day, then the coolant temperature will be maintained in accordance with the schedule at minus 10 °C.
As a rule, the following temperature graphs 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 a temperature schedule of 130/70, which means that at -10 ° C the temperature of the coolant in the supply pipeline of the heating network should be 85.6 degrees, in the supply pipeline of the heating system - 70.8 ° C with a schedule of 105/70 or 65.3 ° C at chart 95/70. The water temperature after the heating system should be 51.7 °C.
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.
| 53,2 | 50,2 | 46,4 | 43,4 | 41,2 | 35,8 |
| 55,7 | 52,3 | 48,2 | 45,0 | 42,7 | 36,8 |
| 58,1 | 54,4 | 50,0 | 46,6 | 44,1 | 37,7 |
| 60,5 | 56,5 | 51,8 | 48,2 | 45,5 | 38,7 |
| 62,9 | 58,5 | 53,5 | 49,8 | 46,9 | 39,6 |
| 65,3 | 60,5 | 55,3 | 51,4 | 48,3 | 40,6 |
| 67,7 | 62,6 | 57,0 | 52,9 | 49,7 | 41,5 |
| 70,0 | 64,5 | 58,8 | 54,5 | 51,0 | 42,4 |
| 72,4 | 66,5 | 60,5 | 56,0 | 52,4 | 43,3 |
| 74,7 | 68,5 | 62,2 | 57,5 | 53,7 | 44,2 |
| 77,0 | 70,4 | 63,8 | 59,0 | 55,0 | 45,0 |
| 79,3 | 72,4 | 65,5 | 60,5 | 56,3 | 45,9 |
| 81,6 | 74,3 | 67,2 | 62,0 | 57,6 | 46,7 |
| 83,9 | 76,2 | 68,8 | 63,5 | 58,9 | 47,6 |
| 86,2 | 78,1 | 70,4 | 65,0 | 60,2 | 48,4 |
| 88,5 | 80,0 | 72,1 | 66,4 | 61,5 | 49,2 |
| 90,8 | 81,9 | 73,7 | 67,9 | 62,8 | 50,1 |
| 93,0 | 83,8 | 75,3 | 69,3 | 64,0 | 50,9 |
| 95,3 | 85,6 | 76,9 | 70,8 | 65,3 | 51,7 |
| 97,6 | 87,5 | 78,5 | 72,2 | 66,6 | 52,5 |
| 99,8 | 89,3 | 80,1 | 73,6 | 67,8 | 53,3 |
| 102,0 | 91,2 | 81,7 | 75,0 | 69,0 | 54,0 |
| 104,3 | 93,0 | 83,3 | 76,4 | 70,3 | 54,8 |
| 106,5 | 94,8 | 84,8 | 77,9 | 71,5 | 55,6 |
| 108,7 | 96,6 | 86,4 | 79,3 | 72,7 | 56,3 |
| 110,9 | 98,4 | 87,9 | 80,7 | 73,9 | 57,1 |
| 113,1 | 100,2 | 89,5 | 82,0 | 75,1 | 57,9 |
| 115,3 | 102,0 | 91,0 | 83,4 | 76,3 | 58,6 |
| 117,5 | 103,8 | 92,6 | 84,8 | 77,5 | 59,4 |
| 119,7 | 105,6 | 94,1 | 86,2 | 78,7 | 60,1 |
| 121,9 | 107,4 | 95,6 | 87,6 | 79,9 | 60,8 |
| 124,1 | 109,2 | 97,1 | 88,9 | 81,1 | 61,6 |
| 126,3 | 110,9 | 98,6 | 90,3 | 82,3 | 62,3 |
| 128,5 | 112,7 | 100,2 | 91,6 | 83,5 | 63,0 |
| 130,6 | 114,4 | 101,7 | 93,0 | 84,6 | 63,7 |
| 132,8 | 116,2 | 103,2 | 94,3 | 85,8 | 64,4 |
| 135,0 | 117,9 | 104,7 | 95,7 | 87,0 | 65,1 |
| 137,1 | 119,7 | 106,1 | 97,0 | 88,1 | 65,8 |
| 139,3 | 121,4 | 107,6 | 98,4 | 89,3 | 66,5 |
| 141,4 | 123,1 | 109,1 | 99,7 | 90,4 | 67,2 |
| 143,6 | 124,9 | 110,6 | 101,0 | 94,6 | 67,9 |
| 145,7 | 126,6 | 112,1 | 102,4 | 92,7 | 68,6 |
| 147,9 | 128,3 | 113,5 | 103,7 | 93,9 | 69,3 |
| 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 handbook "Setting up and operation of water heating networks" (Chapter 4, p. 4.4, p. 153,).
This is a rather laborious and lengthy process, since several values must be read for each outdoor temperature: T1, T3, T2, 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.
Table for calculating the temperature graph in MS Excel
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 T1
- design temperature in the return pipe of the heating network T2
- design temperature in the supply pipe of the heating system T3
- Outdoor air temperature Tn.v.
- Indoor temperature Tv.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.
Entering initial data into the table for calculating the temperature graph
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.
Graphical representation of the temperature graph
The table also considers the temperature of direct network water, taking into account wind speed.
Download temperature chart calculation
energoworld.ru
Appendix e Temperature chart (95 – 70) °С
| Design temperature outdoor | Water temperature in server pipeline | Water temperature in return pipeline | Estimated outdoor temperature | Supply water temperature | Water temperature in return pipeline |
Appendix e
CLOSED HEATING SYSTEM
TV1: G1 = 1V1; G2=G1; Q = G1(h2 –h3)
OPEN HEATING SYSTEM
WITH WATER TANK INTO A DEAD-END DHW SYSTEM
TV1: G1 = 1V1; G2 = 1V2; G3 = G1 - G2;
Q1 \u003d G1 (h2 - h3) + G3 (h3 - hх)
Bibliography
1. Gershunsky B.S. Fundamentals of electronics. Kyiv, Vishcha school, 1977.
2. Meyerson A.M. Radio-measuring equipment. - Leningrad.: Energy, 1978. - 408s.
3. Murin G.A. Thermotechnical measurements. -M.: Energy, 1979. -424 p.
4. Spector S.A. Electrical measurements physical quantities. Tutorial. - Leningrad.: Energoatomizdat, 1987. –320s.
5. Tartakovskii D.F., Yastrebov A.S. Metrology, standardization and technical means measurements. - M .: Higher school, 2001.
6. Heat meters TSK7. Manual. - St. Petersburg.: CJSC TEPLOKOM, 2002.
7. Calculator of the amount of heat VKT-7. Manual. - St. Petersburg.: CJSC TEPLOKOM, 2002.
Zuev Alexander Vladimirovich
Neighboring files in the Process Measurements and Instruments folder
studfiles.net
Heating temperature chart
The task of organizations serving houses and buildings is to maintain the standard temperature. The temperature curve of heating directly depends on the temperature outside.
There are three heating systems
Graph of outside and inside temperature - District heating a large boiler house (CHP), standing at a considerable distance from the city. In this case, the heat supply organization, taking into account heat loss in networks, selects a system with a temperature graph: 150/70, 130/70 or 105/70. The first digit is the temperature of the water in the supply pipe, the second digit is the temperature of the water in the return pipe.
- Small boiler houses, which are located near residential buildings. In this case, the temperature curve 105/70, 95/70 is selected.
- Individual boiler installed on a private house. The most acceptable schedule is 95/70. Although it is possible to reduce the supply temperature even more, since there will be practically no heat loss. Modern boilers operate in automatic mode and maintain a constant temperature in the supply heat pipe. The 95/70 temperature chart speaks for itself. The temperature at the entrance to the house should be 95 ° C, and at the exit - 70 ° C.
AT Soviet times when everything was state-owned, all the parameters of the temperature charts were maintained. If according to the schedule there should be a supply temperature of 100 degrees, then this will be so. Such a temperature cannot be supplied to residents, so elevator units were designed. Water from the return pipeline, cooled down, was mixed into the supply system, thereby lowering the supply temperature to the standard one. In our time of universal economy, the need for elevator nodes is no longer necessary. All heat supply organizations switched to the temperature chart of the heating system 95/70. According to this graph, the coolant temperature will be 95 °C when the outside temperature is -35 °C. As a rule, the temperature at the entrance to the house no longer requires dilution. Therefore, all elevator units must be eliminated or reconstructed. Instead of conical sections that reduce both the speed and volume of the flow, put straight pipes. Seal the supply pipe from the return pipeline with a steel plug. This is one of the heat saving measures. It is also necessary to insulate the facades of houses, windows. Change old pipes and batteries to new ones - modern ones. These measures will increase the air temperature in dwellings, which means you can save on heating temperature. Lowering the temperature on the street is immediately reflected in the residents in the receipts.
heating temperature chart Most Soviet cities were built with an "open" heating system. This is when water from the boiler room comes directly to consumers in homes and is used for personal needs of citizens and heating. During the reconstruction of systems and the construction of new heating systems, a "closed" system is used. The water from the boiler house reaches the heating point in the microdistrict, where it heats the water to 95 °C, which goes to the houses. It turns out two closed rings. This system allows heat supply organizations to significantly save resources for heating water. Indeed, the volume of heated water leaving the boiler room will be almost the same at the entrance to the boiler room. No need to get into the system cold water.
Temperature charts are:
- optimal. The heat resource of the boiler room is used exclusively for heating houses. Temperature control takes place in the boiler room. The supply temperature is 95 °C.
- elevated. The heat resource of the boiler house is used for heating houses and hot water supply. Two-pipe system comes into the house. One pipe is heating, the other pipe is hot water supply. Supply temperature 80 - 95 °C.
- adjusted. The heat resource of the boiler house is used for heating houses and hot water supply. One-pipe system approaches the house. From one pipe in the house, a heat resource is taken for heating and hot water for residents. Supply temperature - 95 - 105 °C.
How to carry out the temperature heating schedule. It is possible in three ways:
- quality (regulation of the temperature of the coolant).
- quantitative (regulation of the coolant volume by turning on additional pumps on the return pipeline, or installing elevators and washers).
- qualitative-quantitative (to regulate both the temperature and the volume of the coolant).
The quantitative method prevails, which is not always able to withstand the heating temperature graph.
Fight against heat supply organizations. This struggle is waged by management companies. By law Management Company is obliged to conclude an agreement with the heat supply organization. Will it be a contract for the supply of heat resources or just an agreement on interaction, the management company decides. An annex to this agreement will be a temperature schedule for heating. The heat supply organization is obliged to approve the temperature schemes in the city administration. The heat supply organization supplies the heat resource to the wall of the house, that is, to the metering stations. By the way, the legislation establishes that thermal workers are obliged to install metering stations in houses at their own expense with an installment payment of the cost for residents. So, having metering devices at the entrance and exit from the house, you can control the heating temperature daily. We take the temperature table, look at the air temperature on the weather site and find in the table the indicators that should be. If there are deviations, you need to complain. Even if the deviations are higher, residents will pay more. At the same time, the windows will be opened and the rooms will be ventilated. It is necessary to complain about insufficient temperature to the heat supply organization. If there is no response, we write to the city administration and Rospotrebnadzor.
Until recently, there was a multiplying coefficient on the cost of heat for residents of houses that were not equipped with common house meters. Due to the sluggishness of managing organizations and thermal workers, ordinary residents suffered.
Important indicator in the heating temperature chart is the return temperature of the network. In all graphs, this is an indicator of 70 ° C. In severe frosts, when heat losses increase, heat supply organizations are forced to turn on additional pumps on the return pipeline. This measure increases the speed of water movement through the pipes, and, therefore, the heat transfer increases, and the temperature in the network is maintained.
Again, during the period of general savings, it is very problematic to force thermal workers to turn on additional pumps, which means increasing electricity costs.
The heating temperature graph is calculated based on the following indicators:
- ambient air temperature;
- supply pipeline temperature;
- return pipeline temperature;
- the amount of heat energy consumed at home;
- required amount of thermal energy.
For different rooms temperature curve is different. For children's institutions (schools, gardens, palaces of art, hospitals), the temperature in the room should be between +18 and +23 degrees according to sanitary and epidemiological standards.
- For sports facilities - 18 °C.
- For residential premises - in apartments not lower than +18 °C, in corner rooms + 20 °C.
- For non-residential premises– 16-18 °C. Based on these parameters, heating schedules are built.
It is easier to calculate the temperature schedule for a private house, since the equipment is mounted right in the house. A zealous owner will provide heating to the garage, bathhouse, and outbuildings. The load on the boiler will increase. We calculate the heat load depending on the lowest possible air temperatures of past periods. We select equipment by power in kW. The most cost-effective and environmentally friendly boiler is natural gas. If gas is brought to you, this is already half the battle done. You can also use bottled gas. At home, you do not have to adhere to standard temperature schedules of 105/70 or 95/70, and it does not matter that the temperature in the return pipeline is not 70 ° C. Adjust the network temperature to your liking.
By the way, many city dwellers would like to put individual counters on the heat and control the temperature chart yourself. Contact the heat supply companies. And there they hear such answers. Most of the houses in the country are built on a vertical heating system. Water is supplied from the bottom - up, less often: from top to bottom. With such a system, the installation of heat meters is prohibited by law. Even if a specialized organization installs these meters for you, the heat supply organization simply will not accept these meters for operation. That is, savings will not work. Installation of meters is possible only with horizontal heating distribution.
In other words, when a heating pipe comes into your home not from above, not from below, but from the entrance corridor - horizontally. At the place of entry and exit of heating pipes, individual heat meters can be installed. Installation of such counters pays off in two years. All houses are now being built with just such a wiring system. Heating appliances are equipped with control knobs (taps). If the temperature in the apartment is high in your opinion, then you can save money and reduce the heating supply. Only ourselves we will save from freezing.
myaquahouse.com
Temperature chart of the heating system: variations, application, shortcomings
The temperature chart of the heating system 95 -70 degrees Celsius is the most demanded temperature chart. By and large, it can be said with certainty that all systems central heating work in this mode. The only exceptions are buildings with autonomous heating.
But also in autonomous systems there may be exceptions when using condensing boilers.
When using boilers operating on the condensation principle, the temperature curves of heating tend to be lower.
Temperature in pipelines depending on the outside air temperature
Application of condensing boilers
For example, when maximum load for a condensing boiler, there will be a mode of 35-15 degrees. This is due to the fact that the boiler extracts heat from the exhaust gases. In a word, with other parameters, for example, the same 90-70, it will not be able to work effectively.
Distinctive properties of condensing boilers are:
- high efficiency;
- profitability;
- optimal efficiency at minimum load;
- quality of materials;
- high price.
You have heard many times that the efficiency of a condensing boiler is about 108%. Indeed, the manual says the same thing.
Condensing boiler Valliant
But how can this be, because we are still with school desk taught that more than 100% does not happen.
- The thing is that when calculating the efficiency of conventional boilers, 100% is taken as the maximum. But ordinary gas boilers for heating a private house simply throw flue gases into the atmosphere, and condensing boilers utilize part of the outgoing heat. The latter will go to heating in the future.
- The heat that will be utilized and used in the second round is added to the efficiency of the boiler. Typically, a condensing boiler utilizes up to 15% of flue gases, this figure is adjusted to the efficiency of the boiler (approximately 93%). The result is a number of 108%.
- Undoubtedly, heat recovery is a necessary thing, but the boiler itself costs a lot of money for such work. The high price of the boiler due to stainless heat exchange equipment, which utilizes heat in the last path of the chimney.
- If instead of such stainless equipment we put ordinary iron equipment, then it will become unusable after a very short span time. Since the moisture contained in the flue gases has aggressive properties.
- main feature condensing boilers lies in the fact that they achieve maximum efficiency with minimum loads. Ordinary boilers (gas heaters), on the contrary, reach the peak of economy at maximum load.
- The beauty of this useful property is that during the entire heating period, the load on heating is not always maximum. On the strength of 5-6 days, an ordinary boiler works at maximum. Therefore, a conventional boiler cannot match the performance of a condensing boiler, which has maximum performance with minimal loads.
You can see a photo of such a boiler a little higher, and a video with its operation can be easily found on the Internet.
Principle of operation
conventional heating system
It is safe to say that the heating temperature schedule of 95 - 70 is the most in demand.
This is explained by the fact that all houses that receive heat from central heat sources are designed to work in this mode. And we have more than 90% of such houses.
District boiler house
The principle of operation of such heat production occurs in several stages:
- heat source (district boiler house), produces water heating;
- heated water, through the main and distribution networks moves towards consumers;
- in the house of consumers, most often in the basement, through the elevator unit, hot water is mixed with water from the heating system, the so-called return flow, the temperature of which is not more than 70 degrees, and then heated to a temperature of 95 degrees;
- further heated water (the one that is 95 degrees) passes through the heaters of the heating system, heats the premises and again returns to the elevator.
Advice. If you have a cooperative house or a society of co-owners of houses, then you can set up the elevator with your own hands, but this requires you to strictly follow the instructions and correctly calculate the throttle washer.
Poor heating system
Very often we hear that people's heating does not work well and their rooms are cold.
There can be many reasons for this, the most common are:
- the temperature schedule of the heating system is not observed, the elevator may be incorrectly calculated;
- house system heating is heavily polluted, which greatly impairs the passage of water through the risers;
- fuzzy heating radiators;
- unauthorized change of the heating system;
- poor thermal insulation of walls and windows.
A common mistake is an incorrectly dimensioned elevator nozzle. As a result, the function of mixing water and the operation of the entire elevator as a whole is disrupted.
This could happen for several reasons:
- negligence and lack of training of operating personnel;
- incorrectly performed calculations in the technical department.
During the many years of operation of heating systems, people rarely think about the need to clean their heating systems. By and large, this applies to buildings that were built during the Soviet Union.
All heating systems must be hydropneumatic flushing in front of everyone heating season. But this is observed only on paper, since ZhEKs and other organizations carry out these works only on paper.
As a result, the walls of the risers become clogged, and the latter become smaller in diameter, which violates the hydraulics of the entire heating system as a whole. The amount of transmitted heat decreases, that is, someone simply does not have enough of it.
You can do hydropneumatic purge with your own hands, it is enough to have a compressor and a desire.
The same applies to cleaning radiators. Over many years of operation, radiators inside accumulate a lot of dirt, silt and other defects. Periodically, at least once every three years, they need to be disconnected and washed.
Dirty radiators greatly impair the heat output in your room.
The most common moment is an unauthorized change and redevelopment of heating systems. When replacing old metal pipes with metal-plastic ones, diameters are not observed. And sometimes various bends are added, which increases local resistance and worsens the quality of heating.
Metal-plastic pipe
Very often, with such unauthorized reconstruction and replacement of heating batteries with gas welding, the number of radiator sections also changes. And really, why not give yourself more sections? But in the end, your housemate, who lives after you, will receive less of the heat he needs for heating. And the last neighbor, who will receive less heat the most, will suffer the most.
An important role is played thermal resistance building envelopes, windows and doors. As statistics show, up to 60% of heat can escape through them.
Elevator node
As we said above, all water jet elevators are designed to mix water from the supply line of heating networks into the return line of the heating system. Thanks to this process, system circulation and pressure are created.
As for the material used for their manufacture, both cast iron and steel are used.
Consider the principle of operation of the elevator in the photo below.
The principle of operation of the elevator
Through branch pipe 1, water from heating networks passes through the ejector nozzle and enters the mixing chamber 3 at high speed. There, water from the return of the building's heating system is mixed with it, the latter is supplied through branch pipe 5.
The resulting water is sent to the heating system supply through diffuser 4.
In order for the elevator to function correctly, it is necessary that its neck be correctly selected. To do this, calculations are made using the formula below:
Where ΔРnas - design circulation pressure in the heating system, Pa;
Gcm - water consumption in the heating system kg / h.
Note! True, for such a calculation, you need a building heating scheme.
The appearance of the elevator unit
Have a warm winter!
Page 2
In the article, we will find out how the average daily temperature is calculated when designing heating systems, how the temperature of the coolant at the outlet of the elevator unit depends on the temperature outside, and what the temperature of the heating batteries can be in winter.
We will touch on the topic self fight cold in the apartment.
Cold in winter is a sore subject for many residents of city apartments.
general information
Here we present the main provisions and excerpts from the current SNiP.
Outside temperature
The design temperature of the heating period, which is included in the design of heating systems, is nothing less than the average temperature of the coldest five-day periods for the eight coldest winters of the last 50 years.
This approach allows, on the one hand, to be prepared for severe frosts that occur only once every few years, and on the other hand, not to invest excessive funds in the project. On the scale of mass construction, we are talking about very significant amounts.
Target room temperature
It should be noted right away that the temperature in the room is affected not only by the temperature of the coolant in the heating system.
Several factors are at work in parallel:
- Air temperature outside. The lower it is, the greater the heat leakage through walls, windows and roofs.
- Presence or absence of wind. A strong wind increases the heat loss of buildings, blowing porches, basements and apartments through unsealed doors and windows.
- The degree of insulation of the facade, windows and doors in the room. It is clear that in the case of a hermetically sealed plastic window with a two-chamber double-glazed window, heat loss will be much lower than with a dry one wooden window and glazing in two threads.
It is curious: now there has been a trend towards the construction of apartment buildings with the maximum degree of thermal insulation. In Crimea, where the author lives, new houses are being built immediately with facade insulation mineral wool or polystyrene and with hermetically closing doors of entrances and apartments.
The facade is covered from the outside with basalt fiber slabs.
- And finally, the actual temperature of the heating radiators in the apartment.
So, what are the current temperature standards in rooms for various purposes?
- In the apartment: corner rooms - not lower than 20C, other living rooms - not lower than 18C, bathroom - not lower than 25C. Nuance: at an estimated air temperature below -31C, more than high values, +22 and +20С (source - Decree of the Government of the Russian Federation of May 23, 2006 “Rules for providing utilities citizens").
- In kindergarten: 18-23 degrees, depending on the purpose of the room for toilets, bedrooms and playrooms; 12 degrees for walking verandas; 30 degrees for indoor swimming pools.
- In educational institutions: from 16C for boarding school bedrooms to +21 in classrooms.
- In theaters, clubs, other places of entertainment: 16-20 degrees for the auditorium and + 22C for the stage.
- For libraries (reading rooms and book depositories) the norm is 18 degrees.
- In grocery stores, the normal winter temperature is 12, and in non-food stores - 15 degrees.
- The temperature in the gyms is maintained at 15-18 degrees.
For obvious reasons, the heat in the gym is useless.
- In hospitals, the maintained temperature depends on the purpose of the room. For example, the recommended temperature after otoplasty or childbirth is +22 degrees, in the wards for premature babies it is maintained at +25, and for patients with thyrotoxicosis (excessive secretion of thyroid hormones) - 15C. In surgical wards, the norm is + 26C.
temperature graph
What should be the temperature of the water in the heating pipes?
It is determined by four factors:
- Air temperature outside.
- Type of heating system. For a single-pipe system, the maximum water temperature in the heating system in accordance with current standards is 105 degrees, for a two-pipe system - 95. The maximum temperature difference between supply and return is 105/70 and 95/70C, respectively.
- The direction of the water supply to the radiators. For houses of the upper bottling (with supply in the attic) and lower (with pairwise looping of the risers and the location of both threads in the basement), the temperatures differ by 2 - 3 degrees.
- Type of heating appliances in the house. Radiators and gas convectors heating have different heat transfer; accordingly, to ensure the same temperature in the room, the temperature regime of heating must be different.
The convector somewhat loses to the radiator in terms of thermal efficiency.
So, what should be the temperature of heating - water in the supply and return pipes - at different outdoor temperatures?
We present only a small part temperature table for the estimated ambient temperature of -40 degrees.
- At zero degrees, the temperature of the supply pipeline for radiators with different wiring is 40-45C, the return one is 35-38. For convectors 41-49 supply and 36-40 return.
- At -20 for radiators, the supply and return must have a temperature of 67-77 / 53-55C. For convectors 68-79/55-57.
- At -40C outside, for all heaters, the temperature reaches the maximum allowable temperature: 95/105, depending on the type of heating system, at the supply and 70C at the return pipe.
Useful extras
To understand the principle of operation of the heating system apartment building, separation of areas of responsibility, you need to know a few more facts.
The temperature of the heating main at the outlet from the CHP and the temperature of the heating system in your home are completely different things. At the same -40, a CHP or boiler house will produce about 140 degrees at the supply. Water does not evaporate only due to pressure.
In the elevator unit of your house, part of the water from the return pipeline, returning from the heating system, is mixed into the supply. The nozzle injects a jet of hot water at high pressure into the so-called elevator and recirculates the masses of cooled water.
Schematic diagram of the elevator.
Why is this needed?
To provide:
- Reasonable mixture temperature. Recall: the heating temperature in the apartment cannot exceed 95-105 degrees.
Attention: for kindergartens, a different temperature norm applies: no higher than 37C. The low temperature of the heating devices has to be compensated by a large heat exchange area. That is why in kindergartens the walls are decorated with radiators of such great length.
- Large volume of water involved in circulation. If you remove the nozzle and let the water flow directly from the supply, the return temperature will not differ much from the supply, which will dramatically increase heat loss on the route and disrupt the operation of the CHP.
If you stop the suction of water from the return, the circulation will become so slow that the return pipeline can simply freeze in winter.
The areas of responsibility are divided as follows:
- The temperature of the water injected into the heating mains is the responsibility of the heat producer - the local CHP or boiler house;
- For the transportation of the coolant with minimal losses - the organization serving the heating networks (KTS - communal heating networks).
Such a state of heating mains, as in the photo, means huge heat losses. This is the area of responsibility of the KTS.
- For maintenance and adjustment of the elevator unit - housing department. In this case, however, the diameter of the elevator nozzle - something on which the temperature of the radiators depends - is coordinated with the CTC.
If your house is cold and all the heating devices are those installed by the builders, you will settle this issue with the residents. They are required to provide the temperatures recommended by sanitary standards.
If you undertake any modification of the heating system, for example, replacing the heating batteries with gas welding, you thereby assume full responsibility for the temperature in your home.
How to deal with the cold
Let us, however, be realistic: most often we have to solve the problem of cold in the apartment ourselves, with our own hands. Not always housing organization can provide you with heat within a reasonable time, and not everyone will be satisfied with sanitary standards: you want your home to be warm.
What will the instructions for dealing with cold in an apartment building look like?
Jumpers in front of radiators
There are jumpers in front of the heaters in most apartments, which are designed to ensure the circulation of water in the riser in any condition of the radiator. For a long time they were supplied with three-way valves, then they began to be installed without any shut-off valves.
The jumper in any case reduces the circulation of the coolant through heater. In the case when its diameter is equal to the diameter of the eyeliner, the effect is especially pronounced.
The simplest way to make your apartment warmer is to insert chokes into the jumper itself and the connection between it and the radiator.
Here, ball valves perform the same function. It's not entirely correct, but it will work.
With their help, it is possible to conveniently adjust the temperature of the heating batteries: when the jumper is closed and the throttle to the radiator is fully open, the temperature is maximum, it is worth opening the jumper and covering the second throttle - and the heat in the room comes to naught.
The great advantage of such a refinement is the minimum cost of the solution. The price of the throttle does not exceed 250 rubles; spurs, couplings and locknuts cost a penny at all.
Important: if the throttle leading to the radiator is at least slightly covered, the throttle on the jumper opens completely. Otherwise, adjusting the heating temperature will result in batteries and convectors that have cooled down at the neighbors.
Another helpful change. With such a tie-in, the radiator will always be evenly hot along the entire length.
Warm floor
Even if the radiator in the room hangs on a return riser with a temperature of about 40 degrees, by modifying the heating system, you can make the room warm.
An output - low-temperature systems of heating.
In a city apartment, it is difficult to use underfloor heating convectors due to the limited height of the room: raising the floor level by 15-20 centimeters will mean completely low ceilings.
Much more real option- warm floor. Due to where larger area heat transfer and more rational distribution of heat in the volume of the room low-temperature heating will warm the room better than a red-hot radiator.
What does the implementation look like?
- Chokes are placed on the jumper and the eyeliner in the same way as in the previous case.
- The outlet from the riser to the heater is connected to metal-plastic pipe, which fits into the screed on the floor.
So that communications do not spoil appearance rooms, they are put away in a box. As an option, the tie-in to the riser is moved closer to the floor level.
It is not a problem at all to transfer the valves and throttles to any convenient place.
Conclusion
You can find more information about the operation of centralized heating systems in the video at the end of the article. warm winters!
Page 3
The building heating system is the heart of all engineering and technical mechanisms of the whole house. Which of its components will be selected will depend on:
- Efficiency;
- Profitability;
- Quality.
Selection of sections for the room
All of the above qualities directly depend on:
- heating boiler;
- pipelines;
- Method of connecting the heating system to the boiler;
- heating radiators;
- coolant;
- Adjustment mechanisms (sensors, valves and other components).
One of the main points is the selection and calculation of sections of heating radiators. In most cases, the number of sections is calculated by design organizations that develop a complete project for building a house.
This calculation is affected by:
- Enclosing materials;
- The presence of windows, doors, balconies;
- Room dimensions;
- room type ( living room, warehouse, corridor);
- Location;
- Orientation to the cardinal points;
- Location in the building of the calculated room (corner or in the middle, on the first floor or last).
The data for the calculation are taken from the SNiP "Construction Climatology". The calculation of the number of sections of heating radiators according to SNiP is very accurate, thanks to which you can perfectly calculate the heating system.
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 reduces 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, usually qualitative regulation is used, for which the temperature graphs of the heating network must be calculated for heating load depending on the outside temperature.
The temperature chart 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 °C 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 via independent scheme, which will allow in the second circuit to keep the usual schedule of 150-70 °C. An increase in the design temperature of the heating water in the supply line leads to a reduction in the consumption of heating water, which reduces the cost of 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 °C with a cutoff of 115/70 °C, in connection with which the regulation of the temperature of the network water is automatically carried out only up to the outdoor temperature of “-20 °C”. 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 |
||||||