Thermal regime of the boiler room. Temperature chart of the heating system: variations, application, shortcomings

When autumn confidently walks across the country, snow flies beyond the Arctic Circle, and in the Urals night temperatures stay below 8 degrees, then the word “heating season” sounds appropriate. People recall past winters and try to figure out the normal temperature of the coolant in the heating system.

Prudent owners of individual buildings carefully revise the valves and nozzles of the boilers. Residents apartment building by October 1, they are waiting, like Santa Claus, a plumber from a management company. The ruler of valves and valves brings warmth, and with it - joy, fun and confidence in the future.

The Gigacalorie Path

Megacities sparkle with high-rise buildings. A cloud of renovation hangs over the capital. Outback prays for five-story buildings. Until demolished, the house has a calorie supply system.

Heating of an economy-class apartment building is carried out through centralized system heat supply. Pipes enter the basement of the building. The supply of heat carrier is regulated by inlet valves, after which water enters the mud collectors, and from there it is distributed through the risers, and from them it is supplied to the batteries and radiators that heat the dwelling.

The number of gate valves correlates with the number of risers. While doing repair work in a single apartment, it is possible to turn off one vertical, and not the whole house.

The spent liquid partially leaves through the return pipe, and partially is supplied to the hot water supply network.

degrees here and there

Water for the heating configuration is prepared at a CHP plant or in a boiler house. The water temperature standards in the heating system are prescribed in building regulations: the component must be heated to 130-150 °C.

The supply is calculated taking into account the parameters of the outside air. So, for the South Ural region, minus 32 degrees is taken into account.

To prevent the liquid from boiling, it must be supplied to the network under a pressure of 6-10 kgf. But this is a theory. In fact, most networks operate at 95-110 ° C, since the network pipes of most settlements are worn out and high pressure tear them up like an ace heating pad.

An extensible concept is the norm. The temperature in the apartment is never equal to the primary indicator of the heat carrier. Here it performs an energy-saving function elevator unit- jumper between the direct and return pipe. The norms of the temperature of the coolant in the heating system on the return in winter allow the preservation of heat at the level of 60 ° C.

The liquid from the straight pipe enters the elevator nozzle, mixes with return water and again goes into the house network for heating. The carrier temperature is lowered by mixing the return flow. What affects the calculation of the amount of heat consumed by residential and utility rooms.

Hot gone

Temperature hot water on sanitary rules at the points of analysis should lie in the range of 60-75 ° C.

In the network, the coolant is supplied from the pipe:

• in winter - from the reverse, so as not to scald users with boiling water;
• in summer - with a straight line, since in summer the carrier is heated no higher than 75 ° C.

A temperature chart is drawn up. Average daily temperature return water should not exceed the schedule by more than 5% at night and 3% during the day.

Parameters of distributing elements

One of the details of warming a home is a riser through which the coolant enters the battery or radiator from the temperature norms of the coolant in the heating system require heating in the riser in winter time in the range of 70-90 °C. In fact, the degrees depend on the output parameters of the CHP or boiler house. In the summer, when hot water is needed only for washing and showering, the range moves to the range of 40-60 ° C.

Observant people may notice that in a neighboring apartment, the heating elements are hotter or colder than in his own.

The reason for the temperature difference in the heating riser is the way the hot water is distributed.

In a single-pipe design, the heat carrier can be distributed:

• above; then the temperature on the upper floors is higher than on the lower ones;
• from below, then the picture changes to the opposite - it is hotter from below.

AT two-pipe system the degree is the same throughout, theoretically 90 ° C in the forward direction and 70 ° C in the opposite direction.

Warm like a battery

Suppose that the structures of the central network are reliably insulated along the entire route, the wind does not walk through the attics, stairwells and basements, the doors and windows in the apartments are insulated by conscientious owners.

We assume that the coolant in the riser complies with the building regulations. It remains to find out what is the norm for the temperature of the heating batteries in the apartment. The indicator takes into account:

• outdoor air parameters and time of day;
• the location of the apartment in terms of the house;
• residential or utility room in the apartment.

Therefore, attention: it is important, not what is the degree of the heater, but what is the degree of air in the room.

During the day in the corner rooms, the thermometer should show at least 20 ° C, and in the centrally located rooms 18 ° C is allowed.

At night, air in the dwelling is allowed to be 17 ° C and 15 ° C, respectively.

Theory of linguistics

The name "battery" is household, denoting a number of identical items. In relation to the heating of housing, this is a series of heating sections.

The temperature standards of heating batteries allow heating not higher than 90 ° C. According to the rules, parts heated above 75 ° C are protected. This does not mean that they need to be sheathed with plywood or bricked. Usually they put a lattice fence that does not interfere with air circulation.

Cast iron, aluminum and bimetallic devices are common.

Consumer choice: cast iron or aluminum

The aesthetics of cast-iron radiators is a byword. They require periodic painting, as the rules stipulate that the work surface should have smooth surface and allows easy removal of dust and dirt.

A dirty coating forms on the rough inner surface of the sections, which reduces the heat transfer of the device. But technical specifications cast iron products at height:

• little susceptible to water corrosion, can be used for more than 45 years;
• they have a high thermal power per 1 section, therefore they are compact;
• they are inert in heat transfer, therefore they smooth out temperature fluctuations in the room well.

Another type of radiators is made of aluminum. Lightweight construction, painted in the factory, does not require painting, easy to clean.

But there is a drawback that overshadows the advantages - corrosion in the aquatic environment. Of course, the inner surface of the heater is insulated with plastic to avoid contact of aluminum with water. But the film may be damaged, then it will begin chemical reaction with the release of hydrogen, when creating overpressure gas aluminum appliance may burst.

The temperature standards of heating radiators are subject to the same rules as batteries: it is not so much the heating of a metal object that is important, but the heating of the air in the room.

In order for the air to warm up well, there must be sufficient heat removal from working surface heating structure. Therefore, it is strongly not recommended to increase the aesthetics of the room with shields in front of the heating device.

Stairwell heating

Since we are talking about apartment building, then it should be mentioned stairwells. The norms for the temperature of the coolant in the heating system state: the degree measure on the sites should not fall below 12 ° C.

Of course, the discipline of the tenants requires that the doors be closed tightly. entrance group, do not leave the transoms of stair windows open, keep the glass intact and promptly report any problems to the management company. If the management company does not take timely measures to insulate the points of probable heat loss and maintain the temperature regime in the house, an application for recalculation of the cost of services will help.

Changes in heating design

Replacement of existing heating appliances in the apartment are produced with the obligatory agreement with management company. Unauthorized change in the elements of warming radiation can disrupt the thermal and hydraulic balance of the structure.

The heating season will begin, a change in the temperature regime in other apartments and sites will be recorded. A technical inspection of the premises will reveal unauthorized changes in the types of heating devices, their number and size. The chain is inevitable: conflict - trial - fine.

So the situation is resolved like this:

• if not old ones are replaced with new radiators of the same size, then this is done without additional approvals; the only thing to apply to the Criminal Code is to turn off the riser for the duration of the repair;
• if new products differ significantly from those installed during construction, then it is useful to interact with the management company.

Heat meters

Let us recall once again that the heat supply network of an apartment building is equipped with heat energy metering units that record both the consumed gigacalories and the cubic capacity of water passed through the house line.

In order not to be surprised by bills containing unrealistic amounts for heat at degrees in the apartment below the norm, before heating season check with the management company whether the metering device is in working order, whether the verification schedule has been violated.

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 normative documents that establish the design, installation and use engineering systems residential and public buildings. They are described in the State building codes and rules:

• 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:

1. The beginning and end of the heating season according to the average daily temperature outside +8 ° C for 3 days;
2. The average temperature inside heated premises of housing and communal and public importance should be 20 ° C, and for industrial buildings 16 ° C;
3. 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 begins to decompose and paintwork. For these reasons, sanitary standards prohibit more heating.

To calculate the optimal indicators, special graphs and tables can be used, in which the norms are determined 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

Autonomous heating helps to avoid many problems that arise with a centralized network, and 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. It is easier to control heating with a gas boiler, 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 standards 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 can be used to correct calculation coolant temperature standards and tell you how to determine the situation 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 help reduce heat loss. It will also reduce heating costs.

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 regulate 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 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 misalignment of heating systems, which means an unequal redistribution of network water across floors. Therefore, quality control is usually used, for which the temperature curves of the heating network for the heating load must be calculated depending on the outside temperature.

The temperature curve 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 according to an independent scheme, which will allow maintaining the usual schedule in the second circuit 150-70 °C. An increase in the design temperature of the 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 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 graph represents the dependence of the degree of heating of water in the system on the temperature of cold outside air. After the necessary calculations, the result is presented in the form of two numbers. The first means the temperature of the water at the inlet to the heating system, and the second at the outlet.

For example, the entry 90-70ᵒС means that for given climatic conditions for heating a certain building, it will be necessary that the coolant at the inlet to the pipes has a temperature of 90ᵒС, and at the exit 70ᵒС.

All values ​​are presented for the outside air temperature for the coldest five-day period. This design temperature is accepted according to the Joint Venture "Thermal protection of buildings". According to the norms, the internal temperature for residential premises is 20ᵒС. The schedule will ensure the correct supply of coolant to the heating pipes. This will avoid hypothermia of the premises and waste of resources.

The need to perform constructions and calculations

The temperature schedule must be developed for each settlement. It allows you to ensure the most competent operation of the heating system, namely:

1. Adjust the heat losses during the supply of hot water to houses with average daily temperature outside air.
2. Prevent insufficient heating of rooms.
3. Oblige thermal power plants to supply consumers with services that meet technological conditions.

Such calculations are necessary both for large heating stations and for boiler houses in small settlements. In this case, the result of calculations and constructions will be called the boiler house schedule.

Ways to control the temperature in the heating system

Upon completion of the calculations, it is necessary to achieve the calculated degree of heating of the coolant. You can achieve it in several ways:

• quantitative;
• quality;
• temporary.

In the first case, the flow rate of water entering the heating network is changed, in the second case, the degree of heating of the coolant is regulated. The temporary option involves a discrete supply of hot liquid to the heating network.

For central system heat supply is most characteristic of high-quality, while the volume of water entering the heating circuit remains unchanged.

Graph types

Depending on the purpose of the heating network, the execution methods differ. The first option is the normal heating schedule. It is a construction for networks that work only for space heating and are centrally regulated.

The increased schedule is calculated for heating networks that provide heating and hot water supply. It is built for closed systems and shows the total load on the hot water supply system.

The adjusted schedule is also intended for networks operating both for heating and for heating. Here, heat losses are taken into account when the coolant passes through the pipes to the consumer.

Drawing up a temperature chart

The constructed straight line depends on the following values:

• normalized air temperature in the room;
• outdoor air temperature;
• the degree of heating of the coolant when it enters the heating system;
• the degree of heating of the coolant at the outlet of the building networks;
• the degree of heat transfer of heating devices;
• thermal conductivity of the outer walls and the overall heat loss of the building.

To perform a competent calculation, it is necessary to calculate the difference between the water temperatures in the direct and return pipes Δt. The higher the value in a straight pipe, the better heat dissipation heating systems and higher indoor temperatures.

In order to rationally and economically consume the coolant, it is necessary to achieve a minimum possible valueΔt. This can be achieved, for example, by working on additional insulation external structures of the house (walls, coverings, ceilings over a cold basement or technical underground).

Calculation of the heating mode

First of all, you need to get all the initial data. Standard values ​​of temperatures of external and internal air are accepted according to the joint venture "Thermal protection of buildings". To find the power of heating devices and heat losses, you will need to use the following formulas.

Heat loss of the building

In this case, the input data will be:

• the thickness of the outer walls;
• thermal conductivity of the material from which the enclosing structures are made (in most cases it is indicated by the manufacturer, denoted by the letter λ);
• surface area of ​​the outer wall;
• climatic region of construction.

First of all, the actual resistance of the wall to heat transfer is found. In a simplified version, you can find it as a quotient of the wall thickness and its thermal conductivity. If a outdoor structure consists of several layers, individually find the resistance of each of them and add the resulting values.

Thermal losses of walls are calculated by the formula:

Q = F*(1/R 0)*(t inside air -t outside air)

Here Q is the heat loss in kilocalories and F is the surface area of ​​the exterior walls. For a more accurate value, it is necessary to take into account the area of ​​\u200b\u200bglazing and its heat transfer coefficient.

Calculation of the surface power of batteries

Specific (surface) power is calculated as a quotient of the maximum power of the device in W and the heat transfer surface area. The formula looks like this:

R beats \u003d R max / F act

Calculation of the coolant temperature

Based on the obtained values, the temperature regime of heating is selected and a direct heat transfer is built. On one axis, the values ​​​​of the degree of heating of the water supplied to the heating system are plotted, and on the other, the outside air temperature. All values ​​are taken in degrees Celsius. The results of the calculation are summarized in a table in which the nodal points of the pipeline are indicated.

It is rather difficult to carry out calculations according to the method. To perform a competent calculation, it is best to use special programs.

For each building, such a calculation is carried out individually by the management company. For an approximate definition of water at the inlet to the system, you can use the existing tables.

1. For large suppliers of thermal energy, coolant parameters are used 150-70ᵒС, 130-70ᵒС, 115-70ᵒС.
2. For small systems with several apartment buildings parameters apply 90-70ᵒС (up to 10 floors), 105-70ᵒС (over 10 floors). A schedule of 80-60ᵒС can also be adopted.
3. When arranging an autonomous heating system for an individual house, it is enough to control the degree of heating using sensors, you can not build a graph.

The performed measures allow determining the parameters of the coolant in the system at a certain point in time. Analyzing the coincidence of the parameters with the graph, you can check the effectiveness heating system. The temperature chart table also indicates the degree of load on the heating system.