Temperature graph during the heating period. Substantiation of the reduced temperature schedule for regulation of centralized heat supply systems

Looking through the statistics of visits to our blog, I noticed that search phrases such as, for example, appear very often “What should be the temperature of the coolant at minus 5 outside?”. Decided to post the old one. schedule quality regulation heat release by average daily temperature 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 an article). Work on this schedule heating network in Ufa (Bashkiria).

I also want to draw attention to the fact that regulation occurs according to average daily outside temperature, so if, for example, outside at night minus 15 degrees, and during the day minus 5, then the coolant temperature will be maintained in accordance with the schedule minus 10 o C.

As a rule, the following temperature charts are used: 150/70 , 130/70 , 115/70 , 105/70 , 95/70 . The schedule is selected depending on the specific local conditions. House heating systems operate according to schedules 105/70 and 95/70. According to schedules 150, 130 and 115/70, main heat networks operate.

Let's look at an example of how to use the chart. Suppose the temperature outside is minus 10 degrees. Heating networks operate according to the temperature schedule 130/70 , which means at -10 o С the temperature of the heat carrier in the supply pipeline of the heating network must be 85,6 degrees, in the supply pipeline of the heating system - 70.8 o C with a schedule of 105/70 or 65.3 about C on a 95/70 schedule. The temperature of the water after the heating system must be 51,7 about S.

As a rule, the temperature values ​​in the supply pipeline of heat networks are rounded off when setting the heat source. For example, according to the schedule, it should be 85.6 ° C, and 87 degrees are set at the CHP or boiler house.

Please do not focus on the diagram at the beginning of the post - it does not correspond to the data from the table.

Calculation of the temperature graph

The method for calculating the temperature graph is described in the reference book (Chapter 4, p. 4.4, p. 153,).

This is quite laborious and long process, since for each outdoor temperature several values ​​\u200b\u200bmust be considered: T 1, T 3, T 2, etc.

To our joy, we have a computer and a MS Excel spreadsheet. A colleague at work shared with me a ready-made table for calculating the temperature graph. She was once made by his wife, who worked as an engineer for a group of regimes in thermal networks.

In order for Excel to calculate and build a graph, it is enough to enter several initial values:

• design temperature in the supply pipeline of the heating network T 1
• design temperature in the return pipeline of the heating network T 2
• design temperature in the supply pipe of the heating system T 3
• Outside temperature T n.v.
• Indoor temperature T v.p.
• coefficient " n» (it is usually not changed and is equal to 0.25)
• Minimum and maximum cut of the temperature graph Cut min, Cut max.

All. nothing more is required of you. The results of the calculations will be in the first table of the sheet. It is highlighted in bold.

The charts will also be rebuilt for the new values.

The table also considers the temperature of direct network water, taking into account wind speed.

Water is heated in network heaters, with selective steam, in peak hot water boilers, after which network water enters the supply line, and then to subscriber heating, ventilation and hot water supply installations.

Heating and ventilation heat loads are uniquely dependent on the outdoor temperature tn.a. Therefore, it is necessary to adjust the heat output in accordance with load changes. You use predominantly central regulation carried out at the CHP, supplemented by local automatic regulators.

With central regulation, it is possible to apply either quantitative regulation, which boils down to a change in the flow of network water in the supply line at a constant temperature, or qualitative regulation, in which the water flow remains constant, but its temperature changes.

A serious drawback of quantitative regulation is the vertical misalignment of heating systems, which means an unequal redistribution of network water across floors. Therefore, 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 graph for the supply and return lines is characterized by the values ​​of the calculated temperatures in the supply and return lines τ1 and τ2 and the calculated outdoor temperature tn.o. So, the schedule 150-70°C means that at the calculated outdoor temperature tn.o. the maximum (calculated) temperature in the supply line is τ1 = 150 and in the return line τ2 - 70°C. Accordingly, the calculated temperature difference is 150-70 = 80°C. Lower design temperature of the temperature curve 70 °С is determined by the need to heat tap water for the needs of hot water supply up to tg. = 60°C, which is dictated by sanitary standards.

The upper design temperature determines the minimum allowable water pressure in the supply lines, excluding water boiling, and therefore the strength requirements, and can vary in a certain range: 130, 150, 180, 200 °C. An increased temperature schedule (180, 200 °С) may be required when connecting subscribers 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 decrease in the consumption of heating water, which reduces the cost of the heating network, but also reduces the generation of electricity from heat consumption. The choice of the temperature schedule for the heat supply system must be confirmed by a feasibility study based on the minimum reduced costs for the CHP and the heat network.

The heat supply of the industrial site of CHPP-2 is carried out according to the temperature schedule of 150/70 °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.

From a series of articles "What to do if it's cold in the apartment"

What is a temperature chart?

The temperature of the water in the heating system must be maintained depending on the actual temperature of the outside air according to the temperature schedule, which is developed by specialists in heat engineering from design and energy supply organizations according to special technique for each source of heat supply, taking into account specific local conditions. These schedules should be developed based on the requirement that, in cold period years in living rooms supported optimum temperature*, equal to 20 - 22 ° С.

When calculating the schedule, heat losses (water temperatures) in the area from the heat supply source to residential buildings are taken into account.

Temperature graphs should be drawn up both for the heating network at the outlet of the heat supply source (boiler house, CHPP), and for pipelines after the heating points of residential buildings (groups of houses), i.e. directly at the entrance to the heating system of the house.

From heat supply sources to heat networks is supplied hot water according to the following temperature charts:*

• from large CHP plants: 150/70°С, 130/70°С or 105/70°С;
• from boiler houses and small CHP plants: 105/70°С or 95/70°С.

*first digit - Maximum temperature direct network water, the second digit is its minimum temperature.

Other temperature schedules may be applied depending on specific local conditions.

So, in Moscow, at the exit from the main sources of heat supply, schedules of 150/70°С, 130/70°С and 105/70°С (maximum/minimum water temperature in the heating system) are used.

Until 1991, such temperature charts annually before the autumn-winter heating season were approved by the administrations of cities and other settlements, which was regulated by the relevant regulatory and technical documents (NTD).

Subsequently, unfortunately, this norm disappeared from the NTD, everything was given to the owners of boiler houses, thermal power plants, and other factories - steamships, who at the same time did not want to lose profits.

However regulatory requirement on the obligation to draw up temperature schedules for heating restored federal law No. 190-FZ of July 27, 2010 "On heat supply". Here is what is regulated in FZ-190 according to temperature chart(the articles of the Law are arranged by the author in their logical sequence):

“... Article 23. Organization of the development of heat supply systems for settlements, urban districts
…3. Authorized ... bodies [see. Art. 5 and 6 FZ-190] should develop, statement and annual update* * heat supply schemes, which should contain:
…7) Optimal temperature chart…
Article 20. Checking readiness for the heating season
…5. Check readiness for heating period heat supply organizations... is carried out in order to ... readiness of these organizations to fulfill the heat load schedule, maintaining the temperature schedule approved by the heat supply scheme…
Article 6. Powers of bodies local government settlements, urban districts in the field of heat supply
1. The powers of local self-government bodies of settlements, urban districts for the organization of heat supply in the respective territories include:
…4) fulfillment of requirements, established rules assessing the readiness of settlements, urban districts for the heating period, and readiness control heat supply organizations, heat network organizations, certain categories of consumers for the heating season;
…6) approval of heat supply schemes settlements, urban districts with a population of less than five hundred thousand people ...;
Article 4, paragraph 2. To the powers of the fed. organ isp. authority authorized to implement the state. heating policies include:
11) approval of heat supply schemes for settlements, mountains. districts with a population of five hundred thousand or more ...
Article 29. Final provisions
…3. Approval of heat supply schemes for settlements ... must be carried out before December 31, 2011.”

And here is what is said about the temperature graphs of heating in the "Rules and norms for the technical operation of the housing stock" (approved by the Post. Gosstroy of the Russian Federation of September 27, 2003 No. 170):

“…5.2. Central heating
5.2.1. System operation central heating residential buildings should provide:
- maintaining the optimum (not below the permissible) air temperature in heated rooms;
- maintaining the temperature of the water entering and returning from the heating system in accordance with the schedule for the quality control of the water temperature in the heating system (Appendix No. 11);
- uniform heating of all heating devices;
5.2.6. The premises of the operating personnel should have:
…e) supply and return water in the heating network and in the heating system, depending on the outdoor temperature, indicating the working water pressure at the inlet, static and maximum allowable pressure in system;…"

Due to the fact that a heat carrier with a temperature not higher than can be supplied to house heating systems: for two-pipe systems– 95 ​​°С; for single-pipe - 105 ° С, at heating points (individual house or group for several houses), before water is supplied to houses, hydraulic elevator units are installed in which direct network water having high temperature, mixed with chilled return water returning from the heating system of the house. After mixing in the hydraulic elevator, the water enters the house system with a temperature according to the "house" temperature chart 95/70 or 105/70 ° С.

The following, as an example, shows the temperature graph of the heating system after heating point a residential building for radiators according to the top-down and bottom-up scheme (with outdoor temperature intervals of 2 °C), for a city with an estimated outdoor air temperature of 15 °C (Moscow, Voronezh, Orel):

WATER TEMPERATURE IN DISCHARGE PIPELINES, deg. C

AT DESIGN OUTSIDE AIR TEMPERATURE

Explanations:
1. In gr. 2 and 4 show the values ​​of the water temperature in the supply pipeline of the heating system:
in the numerator - at a calculated water temperature drop of 95 - 70 °C;
in the denominator - with a calculated difference of 105 - 70 °C.
In gr. 3 and 5 show the water temperatures in the return pipeline, which coincide in their values ​​with calculated differences of 95 - 70 and 105 - 70 °C.

Temperature graph of the heating system of a residential building after a heat point

Source: Rules and Regulations technical operation housing stock, adj. 20
(approved by order of the Gosstroy of the Russian Federation of December 26, 1997 No. 17-139).

Since 2003 they have been operating "Rules and norms for the technical operation of the housing stock"(approved by the Post. Gosstroy of the Russian Federation of September 27, 2003 No. 170), adj. eleven.

For supporting comfortable temperature in the house in heating period it is necessary to control the temperature of the heat carrier in the pipes of heating networks. System workers district heating living quarters is being developed special temperature chart, which depends on weather indicators, climatic features of the region. temperature graph may differ in different settlements, it may also change during the modernization of heating networks.

A schedule is drawn up in the heating network for simple principle- the lower the temperature outside, the higher it should be at the coolant.

This ratio is important basis for work enterprises that provide the city with heat.

For the calculation, an indicator was used, which is based on average daily temperature the five coldest days of the year.

ATTENTION! Compliance temperature regime is important not only for maintaining heat in an apartment building. It also allows you to make the consumption of energy resources in the heating system economical, rational.

The graph, which indicates the temperature of the coolant depending on the outside temperature, allows the most optimal way to distribute between consumers apartment building not only heat, but also hot water.

How is heat regulated in the heating system

Heat regulation in an apartment building during the heating period can be carried out in two ways:

• By changing the flow rate of water at a certain constant temperature. This is a quantitative method.
• The change in the temperature of the coolant at a constant flow rate. This is a quality method.

Economical and practical is second option, at which the temperature regime in the room is observed regardless of the weather. Sufficient heat supply to apartment house will be stable, even if there is a sharp temperature drop outside.

ATTENTION!. The norm is the temperature of 20-22 degrees in the apartment. If the temperature charts are observed, this norm is maintained throughout the heating period, regardless of weather conditions, wind direction.

When the temperature indicator on the street decreases, data is transmitted to the boiler room and the degree of the coolant automatically increases.

A specific table of the ratio of outdoor temperature and coolant depends on factors such as climate, boiler room equipment, technical and economic indicators.

Reasons for using a temperature chart

The basis for the operation of each boiler house serving residential, administrative and other buildings during the heating period is the temperature chart, which indicates the standards for the indicators of the coolant, depending on what the actual temperature is. outdoor temperature.

• Drawing up a schedule makes it possible to prepare the heating for a decrease in the temperature outside.
• It is also energy saving.

ATTENTION! In order to control the temperature of the heating medium and be entitled to recalculation due to non-compliance thermal regime, the heat sensor must be installed in the system district heating. Meters must be checked annually.

Modern construction companies can increase the cost of housing through the use of expensive energy saving technologies during the construction of multi-apartment buildings.

Despite the change construction technologies, the use of new materials for the insulation of walls and other surfaces of the building, compliance with the norms of the temperature of the coolant in the heating system - best way maintain comfortable living conditions.

Features of calculating the internal temperature in different rooms

The rules provide for maintaining the temperature for living quarters at 18˚С, but there are some nuances in this matter.

• For angular rooms of a residential building coolant must provide a temperature of 20 ° C.
• Optimum temperature indicator for the bathroom - 25˚С.
• It is important to know how many degrees should be according to the standards in rooms intended for children. Indicator set from 18˚С to 23˚С. If this is a children's pool, you need to maintain the temperature at 30 ° C.
• Minimum temperature allowed in schools - 21˚C.
• In institutions where mass cultural events are held according to the standards, maximum temperature 21˚С, but the indicator should not fall below the figure 16˚С.

To increase the temperature in the premises during a sharp cold snap or a strong north wind, the boiler house workers increase the degree of energy supply for heating networks.

The heat transfer of batteries is affected by the outside temperature, type heating system, the direction of the flow of the coolant, the state of utility networks, the type of heater, the role of which can be played by both a radiator and a convector.

ATTENTION! The temperature delta between the supply to the radiator and the return should not be significant. Otherwise, a large difference in the coolant in different rooms and even apartment buildings.

The main factor, however, is the weather., which is why measuring outdoor air to maintain a temperature graph is a top priority.

If it is cold outside up to 20˚С, the coolant in the radiator should have an indicator of 67-77˚С, while the norm for the return is 70˚С.

If the street temperature is zero, the norm for the coolant is 40-45˚С, and for the return - 35-38˚С. It should be noted that the temperature difference between supply and return is not large.

Why does the consumer need to know the norms for the supply of coolant?

Payment utilities in the heating column should depend on what temperature the supplier provides in the apartment.

Table of the temperature graph, according to which optimal performance boiler, shows at what temperature of the environment and by how much the boiler room should increase the degree of energy for heat sources in the house.

IMPORTANT! If the parameters of the temperature schedule are not observed, the consumer may demand a recalculation for utilities.

To measure the coolant indicator, it is necessary to drain some water from the radiator and check its degree of heat. Also successfully used thermal sensors, heat meters that can be installed at home.

The sensor is a mandatory equipment for both city boiler houses and ITPs (individual heating points).

Without such devices, it is impossible to make the operation of the heating system economical and productive. Coolant measurement is also carried out in hot water systems.

Useful video

The basis of an economical approach to energy consumption in a heating system of any type is the temperature graph. Its parameters indicate optimal value heating water, thereby optimizing costs. In order to apply these data in practice, it is necessary to learn more about the principles of its construction.

Terminology

Temperature graph - the optimal value of heating the coolant to create a comfortable temperature in the room. It consists of several parameters, each of which directly affects the quality of the entire heating system.

1. The temperature in the inlet and outlet pipes of the heating boiler.
2. The difference between these indicators of heating the coolant.
3. Temperature indoors and outdoors.

The latter characteristics are decisive for the regulation of the first two. Theoretically, the need to increase the heating of water in the pipes comes with a decrease in the temperature outside. But how much should be increased so that the heating of the air in the room is optimal? To do this, draw up a graph of the dependence of the parameters of the heating system.

When calculating it, the parameters of the heating system and the residential building are taken into account. For district heating, the following temperature parameters systems:

• 150°C/70°C. Before reaching the users, the coolant is diluted with water from the return pipe to normalize the incoming temperature.
• 90°C/70°C. In this case, there is no need to install equipment for mixing streams.

According to the current parameters of the system, utilities must monitor compliance with the heating medium heating value in the return pipe. If this parameter is less than normal, it means that the room is not warming up properly. The excess indicates the opposite - the temperature in the apartments is too high.

Temperature chart for a private house

The practice of drawing up such a schedule for autonomous heating not very developed. This is explained by his fundamental difference from centralized. It is possible to control the water temperature in the pipes in manual and automatic mode. If during design and practical implementation the installation of sensors for automatic regulation operation of the boiler and thermostats in each room, then there will be no urgent need to calculate the temperature schedule.

But for calculating future expenses depending on weather conditions, it will be indispensable. In order to compose it according to current rules, the following conditions must be taken into account:

Only after these conditions are met, you can proceed to the calculation part. At this stage, difficulties may arise. The correct calculation of an individual temperature graph is a complex mathematical scheme that takes into account all possible indicators.

However, to facilitate the task, there are ready-made tables with indicators. Below are examples of the most common modes of operation of heating equipment. The following input data were taken as initial conditions:

• The minimum air temperature outside is 30°С
• The optimum room temperature is +22°C.

Based on these data, charts were drawn up for the following types operation of heating systems.

It is worth remembering that these data do not take into account the design features of the heating system. They only show the recommended values ​​\u200b\u200bof the temperature and power of heating equipment, depending on weather conditions.