Economical energy consumption in the heating system can be achieved if certain requirements are met. One option is to have a temperature diagram, which reflects the ratio of the temperature emanating from the heating source to the external environment. The values of the values make it possible to optimally distribute heat and hot water to the consumer.
High-rise buildings are mainly connected to central heating. Sources that convey thermal energy, are boiler houses or thermal power plants. Water is used as a coolant. It is heated to a given temperature.
Having gone through a full cycle through the system, the coolant, already cooled, returns to the source and reheats. Sources are connected to consumers by heating networks. As the environment changes temperature regime, thermal energy should be regulated so that the consumer receives the required volume.
Heat regulation from the central system can be done in two ways:
- Quantitative. In this form, the water flow changes, but its temperature remains constant.
- Qualitative. The temperature of the liquid changes, but its flow does not change.
In our systems, the second regulation option is used, that is, qualitative. Z Here there is a direct relationship between two temperatures: coolant and environment. And the calculation is carried out in such a way as to ensure the heat in the room is 18 degrees and above.
Hence, we can say that the temperature graph of the source is a broken curve. The change in its directions depends on temperature differences (coolant and outside air).
The dependency schedule may vary.
A specific diagram has a dependency on:
- Technical and economic indicators.
- CHP or boiler room equipment.
- Climate.
High coolant values provide the consumer with great thermal energy.
Below is an example of a diagram, where T1 is the coolant temperature, Tnv is the outside air:
A diagram of the returned coolant is also used. A boiler house or thermal power plant can estimate the efficiency of the source using this scheme. It is considered high when the returned liquid arrives chilled.
The stability of the scheme depends on the design values of fluid flow of high-rise buildings. If the flow through the heating circuit increases, the water will return uncooled, as the flow rate will increase. Conversely, with minimal flow, the return water will be sufficiently cooled.
The supplier's interest, of course, is in the supply of return water in a cooled state. But there are certain limits for reducing consumption, since a decrease leads to loss of heat. The consumer’s internal temperature in the apartment will begin to drop, which will lead to violation of building codes and discomfort for ordinary people.
What does it depend on?
The temperature curve depends on two quantities: outside air and coolant. Frosty weather leads to an increase in coolant temperature. When designing a central source, the size of the equipment, building and pipe size are taken into account.
The temperature leaving the boiler room is 90 degrees, so that at minus 23°C, the apartments are warm and have a value of 22°C. Then the return water returns to 70 degrees. Such norms correspond to normal and comfortable living in the house.
Analysis and adjustment of operating modes is carried out using a temperature diagram. For example, the return of liquid with an elevated temperature will indicate high coolant costs. Underestimated data will be considered a consumption deficit.
Previously, for 10-story buildings, a scheme with calculated data of 95-70°C was introduced. The buildings above had their own chart of 105-70°C. Modern new buildings may have a different layout, at the discretion of the designer. More often, there are diagrams of 90-70°C, and maybe 80-60°C.
Temperature chart 95-70:
Temperature chart 95-70 How is it calculated?
A control method is selected, then a calculation is made. The calculated winter and reverse order of water supply, the amount of outside air, and the order at the break point of the diagram are taken into account. There are two diagrams: one of them considers only heating, the second considers heating with consumption hot water.
For an example of calculation, we will use methodological development"Roskommunenergo".
The input data for the heat generating station will be:
- Tnv– the amount of outside air.
- TVN- indoor air.
- T1– coolant from the source.
- T2– reverse flow of water.
- T3- entrance to the building.
We will look at several heat supply options with values of 150, 130 and 115 degrees.
At the same time, at the exit they will have 70°C.
The results obtained are compiled into a single table for subsequent construction of the curve:
So, we have three different schemes that can be used as a basis. It would be more correct to calculate the diagram individually for each system. Here we examined the recommended values, without taking into account the climatic features of the region and the characteristics of the building.
To reduce energy consumption, just select a low temperature setting of 70 degrees and uniform heat distribution throughout the heating circuit will be ensured. The boiler should be taken with a power reserve so that the system load does not affect the quality operation of the unit.
Adjustment
Heating regulator Automatic control is provided by the heating regulator.
It includes the following parts:
- Computing and matching panel.
- Actuator on the water supply section.
- Actuator, which performs the function of mixing liquid from the returned liquid (return).
- Boost pump and a sensor on the water supply line.
- Three sensors (on the return line, on the street, inside the building). There may be several of them in the room.
The regulator closes the liquid supply, thereby increasing the value between return and supply to the value specified by the sensors.
To increase the flow, there is a boost pump and a corresponding command from the regulator. The incoming flow is controlled by a "cold bypass". That is, the temperature decreases. Some of the liquid that has circulated along the circuit is sent to the supply.
Sensors collect information and transmit it to control units, resulting in a redistribution of flows that provide a rigid temperature scheme for the heating system.
Sometimes, a computing device is used that combines hot water and heating regulators.
The hot water regulator has a simpler control scheme. The hot water sensor regulates the flow of water with a stable value of 50°C.
Advantages of the regulator:
- The temperature scheme is strictly maintained.
- Elimination of overheating of the liquid.
- Fuel efficiency and energy.
- The consumer, regardless of the distance, receives heat equally.
Table with temperature graph
The operating mode of boilers depends on the environmental weather.
If we take various objects, for example, a factory premises, multi-storey and a private house, all will have an individual thermal diagram.
In the table we show the temperature diagram of the dependence of residential buildings on outside air:
| Outdoor temperature | Temperature of network water in the supply pipeline | Return water temperature |
| +10 | 70 | 55 |
| +9 | 70 | 54 |
| +8 | 70 | 53 |
| +7 | 70 | 52 |
| +6 | 70 | 51 |
| +5 | 70 | 50 |
| +4 | 70 | 49 |
| +3 | 70 | 48 |
| +2 | 70 | 47 |
| +1 | 70 | 46 |
| 0 | 70 | 45 |
| -1 | 72 | 46 |
| -2 | 74 | 47 |
| -3 | 76 | 48 |
| -4 | 79 | 49 |
| -5 | 81 | 50 |
| -6 | 84 | 51 |
| -7 | 86 | 52 |
| -8 | 89 | 53 |
| -9 | 91 | 54 |
| -10 | 93 | 55 |
| -11 | 96 | 56 |
| -12 | 98 | 57 |
| -13 | 100 | 58 |
| -14 | 103 | 59 |
| -15 | 105 | 60 |
| -16 | 107 | 61 |
| -17 | 110 | 62 |
| -18 | 112 | 63 |
| -19 | 114 | 64 |
| -20 | 116 | 65 |
| -21 | 119 | 66 |
| -22 | 121 | 66 |
| -23 | 123 | 67 |
| -24 | 126 | 68 |
| -25 | 128 | 69 |
| -26 | 130 | 70 |
SNiP
There are certain standards that must be observed in the creation of projects for heating networks and the transportation of hot water to the consumer, where the supply of water steam must be carried out at 400°C, at a pressure of 6.3 Bar. It is recommended that the heat supply from the source be released to the consumer with values of 90/70 °C or 115/70 °C.
Regulatory requirements must be met in compliance with the approved documentation with mandatory approval from the Ministry of Construction of the country.
Today, the most common heating systems in the Federation are water-based. The temperature of the water in the batteries directly depends on the air temperature outside, that is, on the street, during a certain period of time. A corresponding schedule has also been approved by law, according to which responsible specialists calculate temperatures, taking into account local weather conditions and the source of heat supply.
Graphs of coolant temperature depending on the outside temperature are developed taking into account the support of mandatory temperature conditions in the room, those that are considered optimal and comfortable for the average person.
The colder it is outside, the higher the level of heat loss. For this reason, it is important to know which indicators are applicable when calculating the required indicators. You don't need to calculate anything yourself. All figures are approved by the relevant regulatory documents. They are based on the average temperatures of the five coldest days of the year. The period of the last fifty years was also taken with the selection of the eight coldest winters for this time.
Thanks to such calculations, it is possible to prepare for low temperatures in winter, occurring at least once every few years. In turn, this allows significant savings when creating a heating system.
Additional influencing factors
The coolant temperatures themselves are also directly influenced by such equally significant factors as:
- A decrease in temperatures outside, which entails a similar decrease indoors;
- Wind speed - the higher it is, the greater the heat loss through the front door and windows;
- The tightness of walls and joints (installation of metal-plastic windows and insulation of facades significantly affects heat retention).
IN Lately There have been some changes in building codes. For this reason construction companies thermal insulation work is often carried out not only on the facades of apartment buildings, but also in the basements, foundations, roofs, roofing. Accordingly, the cost of such construction projects increases. It is important to know that insulation costs are quite significant, but on the other hand, this is a guarantee of heat savings and reduced heating costs.
For their part, construction companies understand that the costs they incurred for insulating facilities will be fully and soon recouped. This is also beneficial for owners, since utility bills are very high, and if you pay, it is really for the heat received and stored, and not for its loss due to insufficient insulation of the premises.
Radiator temperature
However, regardless of the weather conditions outside the room and how insulated it is, the most important role is still played by the heat transfer of the radiator. Typically, temperatures in central heating systems range from 70 to 90 degrees. However, it is important to take into account that this criterion is not the only one in order to have the desired temperature regime, especially in residential premises, where the temperatures in each individual room should not be the same, depending on the intended purpose.
So, for example, in corner rooms it should not be less than 20 degrees, while in others 18 degrees are allowed. In addition, if the temperature outside drops to -30, the established standards for rooms should be two degrees higher.
Those rooms that are intended for children must have a temperature limit of 18 to 23 degrees, depending on what they are intended for. So in the pool it cannot be less than 30 degrees, and on the veranda it must be at least 12 degrees.
Talking about school educational institution, it should not be below 21 degrees, and in the bedroom of the boarding school - at least 16 degrees. For a public cultural institution, the norm is from 16 degrees to 21, and for a library - no more than 18 degrees.
What affects battery temperature?
In addition to the thermal output of the coolant and the temperatures outside, the heat in the room also depends on the activity of the people inside. The more movements a person makes, the lower the temperature can be and vice versa. This is also necessarily taken into account when distributing heat. As an example, we can take any sports institution where people are a priori in active movement. Here it is not advisable to maintain high temperatures, as this will cause discomfort. Accordingly, an indicator of 18 degrees is optimal.
It can be noted that the thermal performance of batteries inside any premises is affected not only by the outside air temperature and wind speed, but also by:
Approved schedules
Since the temperature outside has a direct impact on the heat inside, a special temperature schedule has been approved.
| Outside temperature indicators | Inlet water, °C | Water in the heating system, °C | Outlet water, °C |
|---|---|---|---|
| 8 °C | from 51 to 52 | 42-45 | from 34 to 40 |
| 7 °C | from 51 to 55 | 44-47 | from 35 to 41 |
| 6 °C | from 53 to 57 | 45-49 | from 36 to 46 |
| 5 °C | from 55 to 59 | 47-50 | from 37 to 44 |
| 4 °C | from 57 to 61 | 48-52 | from 38 to 45 |
| 3 °C | from 59 to 64 | 50-54 | from 39 to 47 |
| 2 °C | from 61 to 66 | 51-56 | from 40 to 48 |
| 1 °C | from 63 to 69 | 53-57 | from 41 to 50 |
| 0 °C | from 65 to 71 | 55-59 | from 42 to 51 |
| -1 °C | from 67 to 73 | 56-61 | from 43 to 52 |
| -2 °C | from 69 to 76 | 58-62 | from 44 to 54 |
| -3 °C | from 71 to 78 | 59-64 | from 45 to 55 |
| -4 °C | from 73 to 80 | 61-66 | from 45 to 56 |
| -5 °C | from 75 to 82 | 62-67 | from 46 to 57 |
| -6 °C | from 77 to 85 | 64-69 | from 47 to 59 |
| -7 °C | from 79 to 87 | 65-71 | from 48 to 62 |
| -8 °C | from 80 to 89 | 66-72 | from 49 to 61 |
| -9 °C | from 82 to 92 | 66-72 | from 49 to 63 |
| -10 °C | from 86 to 94 | 69-75 | from 50 to 64 |
| -11 °C | from 86 to 96 | 71-77 | from 51 to 65 |
| -12 °C | from 88 to 98 | 72-79 | from 59 to 66 |
| -13 °C | from 90 to 101 | 74-80 | from 53 to 68 |
| -14 °C | from 92 to 103 | 75-82 | from 54 to 69 |
| -15 °C | from 93 to 105 | 76-83 | from 54 to 70 |
| -16 °C | from 95 to 107 | 79-86 | from 56 to 72 |
| -17 °C | from 97 to 109 | 79-86 | from 56 to 72 |
| -18 °C | from 99 to 112 | 81-88 | from 56 to 74 |
| -19 °C | from 101 to 114 | 82-90 | from 57 to 75 |
| -20 °C | from 102 to 116 | 83-91 | from 58 to 76 |
| -21 °C | from 104 to 118 | 85-93 | from 59 to 77 |
| -22 °C | from 106 to 120 | 88-94 | from 59 to 78 |
| -23 °C | from 108 to 123 | 87-96 | from 60 to 80 |
| -24 °C | from 109 to 125 | 89-97 | from 61 to 81 |
| -25 °C | from 112 to 128 | 90-98 | from 62 to 82 |
| -26 °C | from 112 to 128 | 91-99 | from 62 to 83 |
| -27 °C | from 114 to 130 | 92-101 | from 63 to 84 |
| -28 °C | from 116 to 134 | 94-103 | from 64 to 86 |
| -29 °C | from 118 to 136 | 96-105 | from 64 to 87 |
| -30 °C | from 120 to 138 | 97-106 | from 67 to 88 |
| -31 °C | from 122 to 140 | 98-108 | from 66 to 89 |
| -32 °C | from 123 to 142 | 100-109 | from 66 to 93 |
| -33 °C | from 125 to 144 | 101-111 | from 67 to 91 |
| -34 °C | from 127 to 146 | 102-112 | from 68 to 92 |
| -35 °C | from 129 to 149 | 104-114 | from 69 to 94 |
What is also important to know?
Thanks to the tabular data, it is not difficult to find out about the temperature indicators of water in central heating systems. The required part of the coolant is measured with an ordinary thermometer at the moment when the system is drained. Identified inconsistencies actual temperatures established standards is the basis for recalculating payment for utility services. General house heat meters have become very relevant today.
Responsibility for the temperature of the water that is heated in the heating main lies with the local thermal power plant or boiler house. Transportation of thermal fluids and minimal losses are entrusted to the organization servicing the heating network. The elevator unit is maintained and configured by the housing department or management company.
It is important to know that the diameter of the elevator nozzle itself must be consistent with the municipal heating network. All questions regarding low indoor temperatures must be resolved with the managing body of the apartment building or other real estate in question. The duty of these bodies is to provide citizens with minimum sanitary temperature standards.
Norms in residential premises
To understand when it is really important to apply for a recalculation of payment for utility services and demand that any measures be taken to provide heat, you need to know the heat standards in residential premises. These norms are fully regulated by Russian legislation.
So, in the warm season, living quarters are not heated and the norm for them is 22-25 degrees Celsius. In cold weather, the following indicators apply:
However, we should not forget about common sense. For example, bedrooms must be ventilated; they should not be too hot, but they cannot be too cold either. The temperature in the children's room should be adjusted according to the age of the child. For a baby this is the upper limit. As you grow older, the bar decreases to the lower limits.
The warmth in the bathroom also depends on the humidity of the room. If the room is poorly ventilated, there is a high content of water in the air, and this creates a feeling of dampness and may not be safe for the health of the occupants.
After installing the heating system, it is necessary to adjust the temperature regime. This procedure must be carried out in accordance with existing standards.
Requirements for coolant temperature are set out in regulatory documents that establish the design, installation and use of engineering systems of residential and public buildings. They are described in the State Building Codes and Rules:
- DBN (V. 2.5-39 Heat networks);
- SNiP 2.04.05 “Heating, ventilation and air conditioning.”
For the calculated supply water temperature, the figure is taken that is equal to the water temperature at the outlet of the boiler, according to its passport data.
For individual heating, deciding what the coolant temperature should be should take into account the following factors:
- The beginning and end of the heating season based on the average daily outdoor temperature of +8 °C for 3 days;
- The average temperature inside heated premises of housing, 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 external factors, the water temperature in the heating system can be from 30 to 90 °C. When heated above 90 °C, dust and paintwork begin to decompose. For these reasons sanitary standards more heating is prohibited.
To calculate optimal indicators, special graphs and tables can be used, which define standards depending on the season:
- With an average reading outside the window of 0 °C, the supply for radiators with different wiring is set at 40 to 45 °C, and the return temperature at 35 to 38 °C;
- At -20 °C, the supply is heated from 67 to 77 °C, and the return rate should be from 53 to 55 °C;
- At -40 °C outside the window, all heating devices are set to the maximum permissible values. On the supply side it is from 95 to 105 °C, and on the return side it is 70 °C.
Optimal values in an individual heating system
H2_2Autonomous heating helps to avoid many problems that arise with a centralized network, and the optimal temperature of the coolant can be adjusted according to the season. In the case of individual heating, the concept of standards 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 ensured by the design features of the heating devices.
It is important to ensure that the coolant in the network does not cool below 70 °C. The optimal temperature is considered to be 80 °C. With a gas boiler, it is easier to control heating, because manufacturers limit the ability to heat the coolant to 90 °C. Using sensors to regulate the gas supply, the heating of the coolant can be adjusted.
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. Control of heating of the coolant is quite conditional with high errors and is carried out by rotary thermostats and mechanical dampers.
Electric boilers allow you to smoothly regulate the heating of the coolant from 30 to 90 °C. They are equipped with an excellent overheat protection system.
Single-pipe and double-pipe lines
The design features of a one-pipe and two-pipe heating network determine different standards for heating the coolant.
For example, for a single-pipe main the maximum norm is 105 °C, and for a two-pipe main it is 95 °C, while the difference between the return and supply should be respectively: 105 - 70 °C and 95 - 70 °C.
Coordination of coolant and boiler temperatures
Regulators help coordinate the temperature of the coolant and the boiler. These are devices that create automatic control and adjustment of return and supply temperatures.
The return temperature depends on the amount of liquid passing through it. Regulators cover the liquid supply and increase the difference between the return and supply to the level required, and the necessary indicators are installed on the sensor.
If the flow needs to be increased, 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 transported from the return to the inlet.
The regulator redistributes the supply and return flows according to the data collected by the sensor and ensures strict temperature standards heating networks.
Ways to reduce heat loss
The above information will help to be used to correctly calculate the coolant temperature norm and tell you how to determine situations when you need to use a regulator.
But it is important to remember that the temperature in the room is affected not only by the temperature of the coolant, street 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 heat loss from your home, you need to worry about its maximum thermal insulation. Insulated walls, sealed doors, and metal-plastic windows will help reduce heat loss. This will also reduce heating costs.
Water is heated in network heaters, selected steam, in peak water boilers, after which the network water enters the supply line, and then to the subscriber heating, ventilation and hot water supply installations.
Heating and ventilation heat loads clearly depend on the outside air temperature tn.v. Therefore, it is necessary to regulate the heat supply in accordance with load changes. You mainly use central regulation, carried out at thermal power plants, supplemented by local automatic regulators.
With central regulation, it is possible to use either quantitative regulation, which boils down to changing 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 misadjustment of heating systems, which means unequal redistribution of network water across floors. Therefore, qualitative regulation is usually used, for which the temperature graphs of the heating network must be calculated for the heating load 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 external temperature tн.o. Thus, a graph of 150-70°C means that at the calculated outside 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 calculated temperature of the temperature chart 70 °C determined by the need to heat tap water for hot water supply needs to tg. = 60°C, which is dictated by sanitary standards.
The upper design temperature determines the minimum permissible water pressure in the supply lines, which excludes 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 °C) may be required when connecting subscribers according to an independent circuit, which will allow maintaining the usual schedule of 150-70 in the second circuit °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 thermal consumption. The choice of temperature schedule for the heat supply system must be confirmed by a technical and economic calculation based on the minimum reduced costs for the CHP plant and the heating network.
Heat supply to the industrial site of CHPP-2 is carried out according to a temperature schedule of 150/70 °C with a cut-off at 115/70 °C, and therefore the temperature of the network water is automatically controlled only up to the outside air temperature of “-20 °C”. The consumption of network water is too high. Exceeding the actual consumption of network water over the calculated one leads to excessive consumption of electrical energy for pumping coolant. The temperature and pressure in the return pipe do not correspond to the temperature curve.
The level of heat loads of consumers currently connected to the CHP plant is significantly lower than what was envisaged by the project. As a result, CHPP-2 has a thermal power reserve exceeding 40% of the installed thermal capacity.
Due to damage to distribution networks belonging to TMUP TTS, drainage from heat supply systems due to the lack of the required pressure drop among consumers and leaks in the heating surfaces of hot water heaters, there is an increased flow of make-up water at the thermal power plant, 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 to external consumers is not adjusted and requires adjustment and adjustment.
Dependence of network water temperatures on outside air temperatures
Table 6.1.
|
Temperature values |
Temperature values |
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|
Outside air |
submitting master's degree |
After the elevator |
reverse master's degree |
Outside air |
applying master's degree |
After the elevator |
To the back th master Ali |
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