To maintain a comfortable temperature in the house during the heating season, it is necessary to control the temperature of the coolant in the pipes of the heating networks. System employees district heating residential premises are being developed special temperature chart, which depends on weather conditions, climatic features region. Temperature graph may differ in different localities, and it may also change when modernizing heating networks.

A schedule is drawn up in the heating network according to simple principle– the lower the temperature outside, the higher the coolant should be.

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 five coldest days of the year.

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

A graph showing the coolant temperature depending on outside temperature, allows for the most optimal distribution between consumers apartment building not only heat, but also hot water.

How is heat regulated in a heating system?

Heat regulation in an apartment building during the heating season can be carried out using two methods:

• By changing the flow of water at a certain constant temperature. This is a quantitative method.
• Changing the temperature of the coolant at a constant volume of flow. This is a qualitative method.

It is economical and practical second option, in which the temperature in the room is maintained regardless of the weather. Supplying sufficient heat to apartment house will be stable, even if there is a sharp change in temperature outside.

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

When the temperature outside decreases, data is transmitted to the boiler room and the coolant temperature automatically increases.

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

Reasons to use a temperature graph

The basis of the operation of each boiler house serving residential, administrative and other buildings throughout heating season is a temperature chart that indicates the coolant performance standards depending on what the actual outside temperature is.

• Drawing up a schedule makes it possible to prepare the heating for a drop in outside temperature.
• It also saves energy resources.

ATTENTION! In order to control the coolant temperature and have the right to recalculation due to non-compliance thermal regime, the heat sensor must be installed in the central heating system. Metering devices must undergo annual inspection.

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

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

Features of calculating 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 should provide a temperature of 20˚C.
• Optimal temperature indicator for the bathroom - 25˚С.
• It is important to know how many degrees there should be according to 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˚С.
• In establishments where cultural events take place, the standards support maximum temperature 21˚С, but the indicator should not fall below 16˚С.

To increase the temperature in the premises during sudden cold snaps or strong north winds, boiler room workers increase the degree of energy supply for heating networks.

The heat transfer of batteries is affected by the outside temperature, type heating system, direction of coolant flow, condition utility networks, a type of heating device, the role of which can be performed by either a radiator or a convector.

ATTENTION! The temperature delta between the radiator supply and return should not be significant. Otherwise, a large difference in coolant will be felt different rooms and even apartments in a multi-story building.

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

If the temperature outside is down to 20˚C, the coolant in the radiator should be 67-77˚C, while the return rate is 70˚C.

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

Why does the consumer need to know the coolant supply standards?

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

The temperature chart table, according to which the boiler should operate optimally, shows at what ambient temperature and by how much the boiler room should increase the energy level for heat sources in the house.

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

To measure the coolant value, you need to drain some water from the radiator and check its heat level. Also successfully used thermal sensors, heat meters that can be installed at home.

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

Without such devices it is impossible to make the heating system work economically and productively. The coolant is also measured in DHW systems.

Useful video

The supply of heat to a room is associated with a simple temperature schedule. The temperature values ​​of the water supplied from the boiler room do not change in the room. They have standard values ​​and range from +70ºС to +95ºС. This temperature schedule for the heating system is the most popular.

Adjusting the air temperature in the house

Not everywhere in the country there is central heating, so many residents install independent systems. Their temperature graph differs from the first option. In this case, temperature indicators are significantly reduced. They depend on the efficiency of modern heating boilers.

If the temperature reaches +35ºС, the boiler will operate at maximum power. It depends on the heating element, where thermal energy can be captured by exhaust gases. If the temperature values ​​are greater than + 70 ºС, then the boiler performance drops. In this case, its technical characteristics indicate an efficiency of 100%.

Temperature schedule and its calculation

What the graph will look like depends on the outside temperature. The more negative the outside temperature, the greater the heat loss. Many people do not know where to get this indicator. This temperature is specified in regulatory documents. The temperature of the coldest five-day period is taken as the calculated value, and the lowest value over the last 50 years is taken.

Graph of the dependence of external and internal temperatures

The graph shows the relationship between external and internal temperatures. Let's say the outside temperature is -17ºС. Drawing a line upward until it intersects with t2, we obtain a point characterizing the temperature of the water in the heating system.

Thanks to the temperature schedule, you can prepare the heating system even for the most severe conditions. It also reduces material costs for 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 strong wind occurs, heat loss increases;
• The temperature inside the room depends on the thermal insulation of the structural elements of the building.

Over the past 5 years, construction principles have changed. Builders increase the value of a home by insulating elements. As a rule, this applies to basements, roofs, and foundations. These expensive measures subsequently allow residents to save on the heating system.

Heating temperature chart

The graph shows the dependence of the temperature of external and internal air. The lower the outside air temperature, the higher the coolant temperature in the system will be.

A temperature schedule is developed for each city during the heating season. In small settlements, a boiler room temperature schedule is drawn up, which provides the required amount of coolant to the consumer.

Change temperature schedule Can several ways:

• quantitative - characterized by a change in the flow rate of coolant supplied to the heating system;
• qualitative - consists of regulating the temperature of the coolant before supplying it to the premises;
• temporary - a discrete method of supplying water to the system.

The temperature curve is a schedule of heating pipes that distributes the heating load and is regulated using centralized systems. There is also an increased schedule; it is created for a closed heating system, that is, to ensure the supply of hot coolant to connected objects. When using an open system, it is necessary to adjust the temperature schedule, since the coolant is consumed not only for heating, but also for domestic water consumption.

The temperature graph is calculated using simple method. Hto build it, necessary initial temperature air data:

• external;
• in room;
• in the supply and return pipelines;
• at the exit of the building.

In addition, you should know the nominal thermal load. All other coefficients are standardized by reference documentation. The system is calculated for any temperature schedule, 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 supply temperature, and the second - the return temperature. The calculation results are entered into 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 schedule is the outside air temperature. The calculation table must be drawn up so that the maximum values ​​of the coolant temperature in the heating system (graph 95/70) ensure heating of the room. Room temperatures are prescribed by regulatory documents.

heating devices

Temperature heating devices

The main indicator is the temperature of heating devices. The ideal temperature schedule 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 range of temperature values ​​is compiled for all types of premises. It depends on the movements performed inside the room: the more movements there are, the lower the air temperature. For example, in sports facilities people move a lot, so the temperature is only +18ºС.

Room temperature

Exist certain factors, from which depends temperature heating devices:

• 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;
• Direction of coolant supply to heating devices. With the top feed, the difference should be 2 ºС, with the bottom – 3 ºС;
• Type of heating devices: heat transfer is different, so the temperature curve will be different.

First of all, the coolant temperature depends on the outside air. For example, the temperature outside is 0ºC. Wherein temperature regime in radiators it should be equal to 40-45ºС at the supply, and 38ºС at the return. When the air temperature is below zero, for example -20ºС, these indicators change. IN in this case the supply temperature becomes 77/55ºС. If the temperature reaches -40ºС, then the indicators become standard, that is, +95/105ºС at the supply, and +70ºС at the return.

Additional options

In order for a certain temperature of the coolant to reach the consumer, it is necessary to monitor the condition 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 the temperature still remains high when it enters the apartments. Optimal value+95ºС. To do this, an elevator unit is installed in the basements, which serves for mixing hot water from the boiler room and coolant from the return pipeline.

Several institutions are responsible for the heating main. The boiler room monitors the supply of hot coolant to the heating system, and the city monitors the condition of the pipelines. heating network. The housing office is responsible for the elevator element. Therefore, in order to solve the problem of coolant supply to new house, you need 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 operation of the heating system and changes in temperature conditions.

Adjustment methods

Dismantling the elevator unit

If the boiler room is responsible for the parameters of the coolant leaving the warm point, then the housing office workers must be responsible for the temperature inside the room. Many residents complain about the cold in their apartments. This occurs due to a deviation in the temperature graph. In rare cases, it happens that the temperature rises by a certain value.

Heating parameters can be adjusted in three ways:

• Reaming the nozzle.

If the supply and return coolant temperatures are significantly underestimated, then it is necessary to increase the diameter of the elevator nozzle. This way, more liquid will pass through it.

How to do this? To begin with, it overlaps shut-off valves(house valves and taps 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 location and put into operation.

To ensure sufficient tightness flange connection, it is necessary to replace the paronite gaskets with rubber ones.

• Silence the suction.

In severe cold weather, when the problem of freezing of the heating system in the apartment arises, the nozzle can be completely removed. In this case, the suction may become a jumper. To do this, you need to plug it with a steel pancake 1 mm thick. This process is carried out only in critical situations, since the temperature in pipelines and heating devices will reach 130ºC.

• Adjustment of difference.

In the middle of the heating season, a significant increase in temperature may 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 pressure gauge is mounted on the return line. 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 simply open it, the cheeks will sag. That is, an increase in pressure drop occurs in the return pipeline. Every day the indicator increases by 0.2 atmospheres, and the temperature in the heating system must be constantly monitored.

Heat supply. Video

How is the heat supply of private and apartment buildings, you can find out from the video below.

When drawing up a heating temperature schedule, it is necessary to take into account various factors. This list includes not only the structural elements of the building, but the outside temperature, as well as the type of heating system.

In contact with

Ph.D. Petrushchenkov V.A., Research Laboratory “Industrial Thermal Power Engineering”, Federal State Autonomous Educational Institution of Higher Education “St. Petersburg State politechnical University Peter the Great", St. Petersburg

1. The problem of reducing the design temperature schedule for regulating heat supply systems nationwide

Over the past decades, in almost all cities of the Russian Federation there has been a very significant gap between the actual and design temperature schedules for regulating heat supply systems. As is known, closed and open systems district heating in the cities of the USSR they were designed using high-quality regulation with a temperature schedule for seasonal load regulation of 150-70 ° C. This temperature schedule was widely used both for thermal power plants and for district boiler houses. But, already starting from the late 70s, significant temperature deviations appeared network water in actual control schedules from their design values ​​at low outside temperatures. Under design conditions based on the outside air temperature, the water temperature in the heat supply pipes decreased from 150 °C to 85...115 °C. The reduction of the temperature schedule by the owners of heat sources was usually formalized as work according to the design schedule of 150-70°C with a “cut” at a lower temperature of 110...130°C. At lower coolant temperatures, it was assumed that the heat supply system would operate according to the dispatch schedule. The author of the article is not aware of the calculated justification for such a transition.

The transition to a lower temperature schedule, for example, 110-70 °C from the design schedule of 150-70 °C should entail a number of serious consequences, which are dictated by balance energy relationships. Due to the reduction in the calculated temperature difference of the network water by 2 times while maintaining the thermal load of heating and ventilation, it is necessary to ensure that the consumption of network water for these consumers also increases by 2 times. The corresponding pressure losses through network water in the heating network and in the heat exchange equipment of the heat source and heating points with the quadratic law of resistance will increase 4 times. Required power increase network pumps should happen 8 times. It is obvious that neither throughput heating networks designed for a schedule of 150-70 °C, nor the installed network pumps will allow the delivery of coolant to consumers with double the flow rate compared to the design value.

In this regard, it is absolutely clear that in order to ensure a temperature schedule of 110-70 °C, not on paper, but in reality, a radical reconstruction of both heat sources and the heating network with heating points will be required, the costs of which are unaffordable for the owners of heat supply systems.

The ban on the use of heat supply control schedules for heating networks with a “cut-off” by temperature, given in clause 7.11 of SNiP 41-02-2003 “Heat networks”, could not in any way affect the widespread practice of its use. In the updated version of this document SP 124.13330.2012, the regime with a “cut-off” temperature is not mentioned at all, that is, there is no direct prohibition on this method of regulation. This means that methods of regulating seasonal load must be chosen in which the main task will be solved - ensuring normalized temperatures in the premises and normalized water temperature for the needs of hot water supply.

In the approved List of national standards and sets of rules (parts of such standards and sets of rules), as a result of which, on a mandatory basis, compliance with the requirements of the Federal Law of December 30, 2009 No. 384-FZ “Technical Regulations on the Safety of Buildings and Structures” (Resolution of the Government of the Russian Federation) is ensured dated December 26, 2014 No. 1521) included the revisions of SNiP after updating. This means that the use of temperature “cutting” today is a completely legal measure, both from the point of view of the List of national standards and sets of rules, and from the point of view of the updated edition of the profile SNiP “Heat networks”.

Federal Law No. 190-FZ of July 27, 2010 “On Heat Supply”, “Rules and Standards technical operation housing stock" (approved by the Decree of the State Construction Committee of the Russian Federation dated September 27, 2003 No. 170), SO 153-34.20.501-2003 "Rules for technical operation power stations and networks Russian Federation” also do not prohibit the regulation of seasonal heat load with a “cut” in temperature.

In the 90s, compelling reasons that explained the radical decrease in the design temperature schedule were considered to be the deterioration of heating networks, fittings, compensators, as well as the inability to provide the necessary parameters at heat sources due to the condition of heat exchange equipment. Despite the large volumes repair work, carried out constantly in heating networks and at heat sources in recent decades, this reason remains relevant today for a significant part of almost any heat supply system.

It should be noted that in technical conditions For connection to heating networks of most heat sources, a design temperature schedule of 150-70 ° C, or close to it, is still given. When coordinating designs for central and individual heating points, an indispensable requirement of the owner of the heating network is to limit the flow of network water from the supply heat pipeline of the heating network during the entire heating period in strict accordance with the design, and not the actual temperature control schedule.

Currently, the country is massively developing heat supply schemes for cities and settlements, in which design schedules for regulation of 150-70 °C, 130-70 °C are considered not only relevant, but also valid for 15 years in advance. At the same time, there are no explanations on how to ensure such schedules in practice, nor is there any clear justification for the possibility of providing an connected heat load at low outdoor temperatures in conditions of real regulation of seasonal heat load.

Such a gap between the declared and actual coolant temperatures of the heating network is abnormal and has nothing to do with the theory of operation of heat supply systems, given, for example, in.

Under these conditions, it is extremely important to analyze the actual situation with the hydraulic operating mode of heating networks and the microclimate of heated premises at the design temperature of the outside air. The actual situation is that, despite a significant decrease in the temperature schedule, when ensuring the design flow rate of network water in urban heating systems, as a rule, there is no significant decrease in the design temperatures in the premises, which would lead to resonant accusations of the owners of heat sources for failure to fulfill their main task: ensuring standard temperatures in rooms. In this regard, the following natural questions arise:

1. What explains this set of facts?

2. Is it possible not only to explain the current state of affairs, but also to justify, based on meeting the requirements of modern regulatory documentation, either a “cut” of the temperature graph at 115°C, or a new temperature graph of 115-70 (60) °C at quality regulation seasonal load?

This problem, naturally, constantly attracts everyone's attention. Therefore, publications appear in periodicals that provide answers to the questions posed and provide recommendations for closing the gap between the design and actual parameters of the heat load control system. In some cities, measures have already been taken to reduce the temperature schedule and an attempt is being made to generalize the results of such a transition.

From our point of view, this problem is discussed most clearly and clearly in the article by V.F. Gershkovich. .

It notes several extremely important provisions, which are, among other things, a generalization of practical actions to normalize the operation of heat supply systems in conditions of low-temperature “cut-off”. It is noted that practical attempts to increase the flow rate in the network in order to bring it into line with the reduced temperature schedule have not led to success. Rather, they contributed to the hydraulic misadjustment of the heating network, as a result of which the flow of network water between consumers was redistributed disproportionately to their thermal loads.

At the same time, while maintaining the design flow rate in the network and reducing the water temperature in the supply line, even at low outdoor temperatures, in a number of cases it was possible to ensure the indoor air temperature at an acceptable level. The author explains this fact by the fact that a very significant part of the heating load is accounted for by heating fresh air, which ensures normal air exchange in the premises. Real air exchange on cold days is far from the standard value, since it cannot be ensured only by opening the vents and sashes of window units or double-glazed windows. The article especially emphasizes that Russian air exchange standards are several times higher than those in Germany, Finland, Sweden, and the USA. It is noted that in Kyiv, a decrease in the temperature schedule due to a “cut” from 150 °C to 115 °C was implemented and did not have negative consequences. Similar work was carried out in the heating networks of Kazan and Minsk.

This article examines the current state of Russian requirements for regulatory documentation on air exchange in premises. Using the example of model problems with averaged parameters of the heat supply system, the influence of various factors on its behavior at a water temperature in the supply line of 115 ° C under design conditions based on outside air temperature, including:

Reducing the air temperature in the premises while maintaining the design water flow in the network;

Increasing water flow in the network in order to maintain indoor air temperature;

Reducing the power of the heating system by reducing air exchange for the design water flow in the network while ensuring the design air temperature in the premises;

Assessment of the power of the heating system by reducing air exchange for the actually achievable increased water flow in the network while ensuring the calculated air temperature in the premises.

2. Initial data for analysis

As initial data, it is assumed that there is a heat supply source with a dominant heating and ventilation load, a two-pipe heating network, central heating and heating substations, heating appliances, air heaters, and water taps. The type of heat supply system is not of fundamental importance. It is assumed that the design parameters of all parts of the heat supply system ensure normal operation of the heat supply system, that is, in the premises of all consumers design temperature t v.r =18 °C subject to the temperature schedule of the heating network of 150-70 °C, the design value of the network water flow, standard air exchange and high-quality regulation of seasonal load. The estimated outside air temperature is equal to the average temperature of a cold five-day period with a supply coefficient of 0.92 at the time of creation of the heat supply system. Mixing factor elevator units is determined by the generally accepted temperature control schedule for heating systems 95-70 °C and is equal to 2.2.

It should be noted that in the updated edition of SNiP “Building Climatology” SP 131.13330.2012 for many cities there was an increase in the calculated temperature of the cold five-day period by several degrees in comparison with the edition of the document SNiP 23-01-99.

3. Calculations of operating modes of the heat supply system at a direct supply water temperature of 115 °C

The work under new conditions of a heat supply system created over decades according to modern standards for the construction period is considered. The design temperature schedule for qualitative regulation of seasonal load is 150-70 °C. It is believed that at the time of commissioning the heat supply system performed its functions exactly.

As a result of the analysis of the system of equations describing the processes in all parts of the heat supply system, its behavior is determined when maximum temperature water in the supply line is 115 °C at the design temperature of the outside air, mixing coefficients of the elevator units are 2.2.

One of the determining parameters of the analytical study is the consumption of network water for heating and ventilation. Its value is accepted in the following options:

The design flow rate in accordance with the schedule is 150-70 °C and the declared heating and ventilation load;

The flow rate value that provides the calculated air temperature in the premises under design conditions based on the outside air temperature;

The actual maximum possible value of network water flow, taking into account the installed network pumps.

3.1. Reducing indoor air temperature while maintaining attached heat loads

Let's determine how the average temperature in the rooms will change at the temperature of the network water in the supply line t o 1 = 115 ° C, the design consumption of network water for heating (we will assume that the entire load is heating, since the ventilation load is of the same type), based on the design schedule 150-70 °C, at outside air temperature t n.o = -25 °C. We assume that at all elevator nodes the mixing coefficients u are calculated and equal

For the design design operating conditions of the heat supply system ( , , , ), the following system of equations is valid:

where is the average value of the heat transfer coefficient of all heating devices with a total heat exchange area F, is the average temperature difference between the coolant of heating devices and the air temperature in the premises, G o is the estimated flow rate of network water entering the elevator units, G p is the estimated flow rate of water entering in heating devices, G p =(1+u)G o , c – specific mass isobaric heat capacity of water, - average design value of the building’s heat transfer coefficient, taking into account the transport of thermal energy through external fences with a total area A and the cost of thermal energy for heating the standard consumption of external air.

At a reduced temperature of the network water in the supply line t o 1 =115 °C, while maintaining the design air exchange, the average air temperature in the rooms decreases to the value t in. The corresponding system of equations for design conditions for outside air will have the form

, (3)

where n is the exponent in the criterion dependence of the heat transfer coefficient of heating devices on the average temperature pressure, see, table. 9.2, p.44. For the most common heating devices in the form of cast iron sectional radiators and steel panel convectors of the RSV and RSG types, when the coolant moves from top to bottom, n = 0.3.

Let us introduce the notation , , .

From (1)-(3) follows the system of equations

,

,

whose solutions have the form:

, (4)

(5)

. (6)

For given design values ​​of heat supply system parameters

,

Equation (5), taking into account (3) for a given temperature of direct water under design conditions, allows us to obtain a relationship for determining the air temperature in the premises:

The solution to this equation is t = 8.7°C.

Relative thermal power heating system is equal

Consequently, when the temperature of direct network water changes from 150 °C to 115 °C, the average indoor air temperature decreases from 18 °C to 8.7 °C, and the thermal power of the heating system drops by 21.6%.

The calculated values ​​of water temperatures in the heating system for the accepted deviation from the temperature graph are equal to °C, °C.

The calculation performed corresponds to the case when the external air flow rate during operation of the ventilation and infiltration system corresponds to the design standard values ​​up to the external air temperature t n.o = -25°C. Since in residential buildings, as a rule, natural ventilation is used, organized by residents when ventilating with the help of vents, window sashes and micro-ventilation systems for double-glazed windows, it can be argued that at low outdoor temperatures the flow rate of cold air entering the premises, especially after practically complete replacement window units for double-glazed windows is far from the standard value. Therefore, the air temperature in residential premises is in fact significantly higher than a certain value t = 8.7°C.

3.2 Determining the power of the heating system by reducing indoor air ventilation at the estimated flow of network water

Let us determine how much it is necessary to reduce the cost of thermal energy for ventilation in the considered non-design mode low temperature network water of the heating network so that the average air temperature in the premises remains at the standard level, that is, t in = t in.r = 18°C.

The system of equations describing the process of operation of the heat supply system under these conditions will take the form

A joint solution (2’) with systems (1) and (3), similar to the previous case, gives the following relationships for the temperatures of various water flows:

,

,

.

The equation for a given direct water temperature under design conditions based on the outside air temperature allows one to find the reduced relative load heating systems (only the power of the ventilation system was reduced, heat transfer through the external fences was exactly preserved):

The solution to this equation is =0.706.

Consequently, when the temperature of direct network water changes from 150°C to 115°C, maintaining the indoor air temperature at 18°C ​​is possible by reducing the total thermal power of the heating system to 0.706 of the design value by reducing the cost of heating the outside air. The thermal output of the heating system drops by 29.4%.

The calculated values ​​of water temperatures for the accepted deviation from the temperature graph are equal to °C, °C.

3.4 Increasing the flow of network water in order to ensure the standard air temperature in the premises

Let us determine how the consumption of network water in the heating network for heating needs should increase when the temperature of network water in the supply line decreases to t o 1 = 115 ° C under design conditions based on the outside air temperature t n.o = -25 ° C, so that the average temperature in indoor air remained at the standard level, that is, t in =t in.p =18°C. Ventilation of premises corresponds to the design value.

The system of equations describing the process of operation of the heat supply system, in this case, will take the form taking into account the increase in the value of the network water flow rate to G o y and the water flow rate through the heating system G pu = G ou (1+u) with a constant value of the mixing coefficient of the elevator units u= 2.2. For clarity, let us reproduce equations (1) in this system

.

From (1), (2”), (3’) follows a system of equations of intermediate form

The solution to the above system has the form:

°С, t o 2 =76.5°С,

So, when the temperature of direct network water changes from 150 °C to 115 °C, maintaining the average indoor air temperature at 18 °C is possible by increasing the flow rate of network water in the supply (return) line of the heating network for the needs of heating and ventilation systems by 2 .08 times.

It is obvious that there is no such reserve for the consumption of network water both at heat sources and at pumping stations if available. In addition, such a high increase in the flow of network water will lead to an increase in pressure losses due to friction in the pipelines of the heating network and in the equipment of heating points and heat sources by more than 4 times, which cannot be realized due to the lack of supply of network pumps in terms of pressure and engine power . Consequently, an increase in network water consumption by 2.08 times due to an increase only in the number of installed network pumps while maintaining their pressure will inevitably lead to unsatisfactory operation of elevator units and heat exchangers of most of the heating points of the heating supply system.

3.5 Reducing the power of the heating system by reducing indoor air ventilation in conditions of increased consumption of network water

For some heat sources, the flow of network water in the mains can be higher than the design value by tens of percent. This is due both to the reduction in heat loads that has taken place in recent decades, and to the presence of a certain performance reserve of installed network pumps. Let us take the maximum relative value of the network water flow equal to =1.35 from the design value. Let us also take into account the possible increase in the estimated outside air temperature according to SP 131.13330.2012.

Let us determine how much it is necessary to reduce average consumption outdoor air for ventilation of premises in the mode of reduced temperature of heating network water, so that the average air temperature in the premises remains at the standard level, that is, t = 18 °C.

For a reduced temperature of the network water in the supply line t o 1 =115°C, the air flow in the premises is reduced in order to maintain the calculated value of t =18°C in conditions of an increase in the flow of network water by 1.35 times and an increase in the design temperature of the cold five-day period. The corresponding system of equations for the new conditions will have the form

The relative reduction in thermal power of the heating system is equal to

. (3’’)

From (1), (2’’’), (3’’) the solution follows

,

,

.

For given values ​​of the heating system parameters and =1.35:

; =115 °C; =66 °C; =81.3 °C.

Let us also take into account the increase in the temperature of the cold five-day period to the value tn.o_ = -22 °C. The relative thermal power of the heating system is equal to

The relative change in the total heat transfer coefficients is equal and is due to a decrease in the air flow of the ventilation system.

For houses built before 2000, the share of thermal energy costs for ventilation of premises in the central regions of the Russian Federation is 40...45%, accordingly, the drop in air flow of the ventilation system should occur approximately 1.4 times in order for the overall heat transfer coefficient to be 89% of the design value .

For houses built after 2000, the share of ventilation costs increases to 50...55%; a drop in air flow of the ventilation system by approximately 1.3 times will maintain the calculated air temperature in the premises.

Above in 3.2 it is shown that at the design values ​​of network water flow rates, indoor air temperature and design outdoor air temperature, a decrease in the network water temperature to 115°C corresponds to a relative power of the heating system of 0.709. If this reduction in power is attributed to a decrease in the heating of ventilation air, then for houses built before 2000 the drop in air flow of the indoor ventilation system should occur by approximately 3.2 times, for houses built after 2000 - by 2.3 times.

Analysis of measurement data from heat metering units of individual residential buildings shows that a decrease in consumed heat energy on cold days corresponds to a decrease in standard air exchange by 2.5 times or more.

4. The need to clarify the design heating load of heat supply systems

Let the declared load of the heating system created in recent decades be equal to . This load corresponds to the design temperature of the outside air, relevant during the construction period, accepted for certainty t n.o = -25 °C.

Below is an assessment of the actual reduction in the stated design heating load, caused by the influence of various factors.

Increasing the design outdoor temperature to -22 °C reduces the design heating load to (18+22)/(18+25)x100%=93%.

In addition, the following factors lead to a reduction in the design heating load.

1. Replacement of window units with double-glazed windows, which occurred almost everywhere. The share of transmission losses of thermal energy through windows is about 20% of the total heating load. Replacing window units with double-glazed windows led to an increase in thermal resistance from 0.3 to 0.4 m 2 ∙K/W, accordingly, the thermal power of heat loss decreased to the value: x100% = 93.3%.

2. For residential buildings, the share of ventilation load in the heating load in projects completed before the beginning of the 2000s is about 40...45%, later - about 50...55%. Let us take the average share of the ventilation component in the heating load to be 45% of the declared heating load. It corresponds to an air exchange rate of 1.0. According to modern STO standards, the maximum air exchange rate is at the level of 0.5, the average daily air exchange rate for a residential building is at the level of 0.35. Consequently, a decrease in the air exchange rate from 1.0 to 0.35 leads to a drop in the heating load of a residential building to the following value:

x100%=70.75%.

3. The ventilation load is demanded randomly by different consumers, therefore, like the DHW load for a heat source, its value is not summed up additively, but taking into account the hourly unevenness coefficients. Share maximum load ventilation as part of the declared heating load is 0.45x0.5/1.0=0.225 (22.5%). We will estimate the coefficient of hourly unevenness to be the same as for hot water supply, equal to K hour.vent = 2.4. Hence, total load heating systems for the heat source, taking into account the reduction in the maximum ventilation load, the replacement of window units with double-glazed windows and the non-simultaneous demand for ventilation load, will be 0.933x(0.55+0.225/2.4)x100%=60.1% of the declared load.

4. Taking into account the increase in the design outside air temperature will lead to an even greater drop in the design heating load.

5. The completed estimates show that clarification of the thermal load of heating systems can lead to its reduction by 30...40%. This reduction in the heating load allows us to expect that, while maintaining the design flow rate of network water, the design air temperature in the premises can be ensured by implementing a “cut-off” of the direct water temperature at 115 °C for low outdoor temperatures (see results 3.2). This can be stated with even greater justification if there is a reserve in the amount of network water consumption at the heat source of the heating supply system (see results 3.4).

The above estimates are illustrative in nature, but it follows from them that, based on modern requirements of regulatory documentation, one can expect both a significant reduction in the total design heating load of existing consumers for a heat source, and a technically justified operating mode with a “cut” of the temperature schedule for seasonal load regulation at 115°C. The required degree of actual reduction in the declared load of heating systems should be determined during full-scale tests for consumers of a specific heating main. The calculated temperature of the return network water is also subject to clarification during field tests.

It should be borne in mind that qualitative regulation of seasonal load is not sustainable from the point of view of distribution of thermal power among heating devices for vertical single-pipe heating systems. Therefore, in all the calculations given above, while ensuring the average design air temperature in the premises, there will be some change in the air temperature in the premises along the riser during the heating period at different temperatures outside air.

5. Difficulties in implementing standard indoor air exchange

Let's consider the cost structure of the thermal power of the heating system of a residential building. The main components of heat losses, compensated by the flow of heat from heating devices, are transmission losses through external fences, as well as the cost of heating the outside air entering the premises. Fresh air consumption for residential buildings is determined by the requirements of sanitary and hygienic standards, which are given in section 6.

IN residential buildings x the ventilation system is usually natural. The air flow rate is ensured by periodic opening of the vents and window sashes. It should be borne in mind that since 2000, the requirements for the heat-protective properties of external fences, primarily walls, have increased significantly (2…3 times).

From the practice of developing energy passports for residential buildings, it follows that for buildings built from the 50s to the 80s of the last century in the central and northwestern regions, the share of thermal energy for standard ventilation (infiltration) was 40...45%, for buildings built later, 45...55%.

Before the advent of double-glazed windows, air exchange was regulated by vents and transoms, and on cold days the frequency of their opening decreased. With the widespread use of double-glazed windows, ensuring standard air exchange has become even more bigger problem. This is due to a tenfold reduction in uncontrolled infiltration through cracks and the fact that frequent ventilation by opening the window sashes, which alone can ensure normal air exchange, does not actually occur.

There are publications on this topic, see, for example,. Even with periodic ventilation, there are no quantitative indicators indicating the air exchange of the premises and its comparison with the standard value. As a result, in fact, air exchange is far from standard and a number of problems arise: relative humidity increases, condensation forms on the glazing, mold appears, persistent odors, content increases carbon dioxide in the air, which collectively led to the coining of the term “sick building syndrome.” In some cases, due to a sharp decrease in air exchange, a vacuum occurs in the premises, leading to the overturning of air movement in the exhaust ducts and the entry of cold air into the premises, the flow of dirty air from one apartment to another, and freezing of the walls of the ducts. As a result, builders face the problem of using more advanced ventilation systems that can provide savings on heating costs. In this regard, it is necessary to use ventilation systems with controlled air inflow and removal, heating systems with automatic regulation heat supply to heating devices (ideally systems with apartment-to-apartment connections), sealed windows and entrance doors to apartments.

Confirmation that the ventilation system of residential buildings operates with a performance significantly lower than the design one is the lower, in comparison with the calculated, consumption of thermal energy during the heating period, recorded by the thermal energy metering units of buildings.

The calculation of the ventilation system of a residential building, carried out by the staff of St. Petersburg State Polytechnic University, showed the following. Natural ventilation in the free air flow mode, on average for the year, almost 50% of the time is less than the calculated one (the cross-section of the exhaust duct is designed according to current standards ventilation of multi-apartment residential buildings for the conditions of St. Petersburg for standard air exchange for an outside temperature of +5 ° C), in 13% of the time the ventilation is more than 2 times less than the calculated one, and in 2% of the time there is no ventilation. For a significant part of the heating period, when the outside air temperature is less than +5 °C, ventilation exceeds the standard value. That is, without special adjustment at low outside air temperatures it is impossible to ensure standard air exchange; at outside air temperatures of more than +5°C, air exchange will be lower than standard if a fan is not used.

6. Evolution of regulatory requirements for indoor air exchange

The costs of heating outdoor air are determined by the requirements given in regulatory documentation, which have undergone a number of changes over the long period of building construction.

Let's look at these changes using the example of residential apartment buildings.

In SNiP II-L.1-62, part II, section L, chapter 1, in force until April 1971, air exchange rates for living rooms were 3 m 3 / h per 1 m 2 of room area, for kitchens with electric stoves the air exchange rate 3, but not less than 60 m 3 / h, for a kitchen with a gas stove - 60 m 3 / h for two-burner stoves, 75 m 3 / h for three-burner stoves, 90 m 3 / h for four-burner stoves. Estimated temperature of living rooms +18 °C, kitchen +15 °C.

SNiP II-L.1-71, part II, section L, chapter 1, in force until July 1986, specifies similar standards, but for kitchens with electric stoves the air exchange rate of 3 is excluded.

In SNiP 2.08.01-85, in force until January 1990, air exchange standards for living rooms were 3 m 3 / h per 1 m 2 of room area, for a kitchen without specifying the type of stoves - 60 m 3 / h. Despite the different standard temperature in living quarters and in the kitchen, for thermotechnical calculations it is proposed to take the internal air temperature of +18°C.

In SNiP 2.08.01-89, in force until October 2003, the air exchange standards are the same as in SNiP II-L.1-71, part II, section L, chapter 1. The indication of internal air temperature +18 ° is retained WITH.

In SNiP 31-01-2003, which is still in force, new requirements appear, given in 9.2-9.4:

9.2 Design air parameters in the premises of a residential building should be taken according to the optimal standards of GOST 30494. The air exchange rate in the premises should be taken in accordance with Table 9.1.

Table 9.1

Room	Multiplicity or magnitude air exchange, m 3 per hour, not less
	in non-working hours	in mode service
Bedroom, common room, children's room	0,2	1,0
Library, office	0,2	0,5
Pantry, linen, dressing room	0,2	0,2
Gym, billiard room	0,2	80 m 3
Washing, ironing, drying	0,5	90 m 3
Kitchen with electric stove	0,5	60 m 3
Room with gas-using equipment	1,0	1.0 + 100 m 3
Room with heat generators and solid fuel stoves	0,5	1.0 + 100 m 3
Bathroom, shower, toilet, combined toilet	0,5	25 m 3
Sauna	0,5	10 m 3 for 1 person
Elevator machine room	-	By calculation
Parking	1,0	By calculation
Garbage collection chamber	1,0	1,0

The air exchange rate in all ventilated rooms not listed in the table in non-operating mode must be at least 0.2 room volume per hour.

9.3 When performing thermal engineering calculations of the enclosing structures of residential buildings, the temperature of the internal air of heated premises should be taken to be at least 20 °C.

9.4 The heating and ventilation system of the building must be designed to ensure that the internal air temperature in the premises during the heating period is within the limits optimal parameters, established by GOST 30494, with design parameters of outdoor air for the relevant construction areas.

From this it can be seen that, firstly, the concepts of room maintenance mode and non-working mode appear, during which, as a rule, very different quantitative requirements for air exchange are imposed. For residential premises (bedrooms, common rooms, children's rooms), which make up a significant part of the apartment area, air exchange rates under different modes differ by 5 times. When calculating the heat losses of the building being designed, the air temperature in the premises must be taken to be at least 20°C. In residential premises, the frequency of air exchange is standardized, regardless of the area and number of residents.

The updated version of SP 54.13330.2011 partially reproduces the information of SNiP 31-01-2003 in its original edition. Air exchange standards for bedrooms, common rooms, children's rooms with the total area of ​​the apartment per person less than 20 m 2 - 3 m 3 / h per 1 m 2 of room area; the same if the total area of ​​the apartment per person is more than 20 m 2 - 30 m 3 / h per person, but not less than 0.35 h -1; for a kitchen with electric stoves 60 m 3 / h, for a kitchen with a gas stove 100 m 3 / h.

Therefore, to determine the average daily hourly air exchange, it is necessary to assign the duration of each mode, determine the air flow in different rooms during each mode, and then calculate the average hourly need for fresh air in the apartment, and then in the house as a whole. Repeated changes in air exchange in a particular apartment during the day, for example, in the absence of people in the apartment during working hours or on weekends, will lead to significant uneven air exchange during the day. At the same time, it is obvious that the non-simultaneous action of these modes in different apartments will lead to equalization of the house load for ventilation needs and to a non-additive addition of this load for different consumers.

An analogy can be drawn with the non-simultaneous use DHW loads consumers, which obliges the introduction of an hourly unevenness coefficient when determining the DHW load for a heat source. As is known, its value for a significant number of consumers in regulatory documentation is assumed to be 2.4. A similar value for the ventilation component of the heating load allows us to assume that the corresponding total load will also actually decrease by at least 2.4 times due to the non-simultaneous opening of vents and windows in different residential buildings. In public and industrial buildings a similar picture is observed with the difference that during non-working hours ventilation is minimal and is determined only by infiltration through leaks in light barriers and external doors.

Taking into account the thermal inertia of buildings also allows one to focus on the average daily values ​​of thermal energy consumption for air heating. Moreover, most heating systems do not have thermostats to maintain indoor air temperature. It is also known that central control of the temperature of network water in the supply line for heating systems is carried out according to the temperature of the outside air, averaged over a period of about 6-12 hours, and sometimes over a longer period of time.

Therefore, it is necessary to perform calculations of the standard average air exchange for residential buildings of different series in order to clarify the design heating load of buildings. Similar work needs to be done for public and industrial buildings.

It should be noted that these current regulatory documents apply to newly designed buildings in terms of designing ventilation systems for premises, but indirectly they not only can, but should also be a guide to action when clarifying the thermal loads of all buildings, including those that were built according to other standards given above.

Organizational standards have been developed and published regulating air exchange standards in the premises of multi-apartment residential buildings. For example, STO NPO AVOK 2.1-2008, STO SRO NP SPAS-05-2013, Energy saving in buildings. Calculation and design of ventilation systems for residential multi-apartment buildings (Approved by the general meeting of SRO NP SPAS dated March 27, 2014).

Basically, the standards given in these documents correspond to SP 54.13330.2011 with some reductions individual requirements(for example, for a kitchen with a gas stove, a single air exchange is not added to 90 (100) m 3 / h; during non-working hours, an air exchange of 0.5 h -1 is allowed in a kitchen of this type, whereas in SP 54.13330.2011 - 1.0 h -1).

The reference Appendix B STO SRO NP SPAS-05-2013 provides an example of calculating the required air exchange for a three-room apartment.

Initial data:

Total area of ​​the apartment F total = 82.29 m2;

Residential area F lived = 43.42 m2;

Kitchen area – Fkh = 12.33 m2;

Bathroom area – F ext = 2.82 m2;

Restroom area – Fub = 1.11 m2;

Room height h = 2.6 m;

The kitchen has an electric stove.

Geometric characteristics:

Volume of heated premises V = 221.8 m 3 ;

The volume of residential premises V lived = 112.9 m 3;

Kitchen volume V kx = 32.1 m 3;

The volume of the restroom Vub = 2.9 m3;

Bathroom volume Vin = 7.3 m3.

From the above calculation of air exchange it follows that the apartment ventilation system must provide the calculated air exchange in maintenance mode (in design operation mode) - L tr work = 110.0 m 3 /h; in non-operating mode - L tr slave = 22.6 m 3 / h. The given air flow rates correspond to an air exchange rate of 110.0/221.8=0.5 h -1 for the maintenance mode and 22.6/221.8=0.1 h -1 for the non-operating mode.

The information provided in this section shows that in existing regulatory documents, with different occupancy of apartments, the maximum air exchange rate is in the range of 0.35...0.5 h -1 for the heated volume of the building, in non-operating mode - at the level of 0.1 h -1. This means that when determining the power of the heating system, which compensates for transmission losses of thermal energy and the cost of heating the outside air, as well as the consumption of network water for heating needs, one can focus, as a first approximation, on the average daily value of the air exchange rate of residential apartment buildings of 0.35 hours - 1 .

Analysis of energy passports of residential buildings developed in accordance with SNiP 02/23/2003 “ Thermal protection buildings”, shows that when calculating the heating load of a house, the air exchange rate corresponds to the level of 0.7 h -1, which is 2 times higher than the recommended value above, which does not contradict the requirements of modern service stations.

It is necessary to clarify the heating load of buildings built according to standard projects, based on a reduced average air exchange rate, which will correspond to existing Russian standards and will allow us to get closer to the standards of a number of European Union countries and the United States.

7. Justification for reducing the temperature schedule

Section 1 shows that the temperature schedule of 150-70 °C, due to the actual impossibility of its use in modern conditions, should be lowered or modified by justifying the “cut” in temperature.

The above calculations of various operating modes of the heat supply system in off-design conditions allow us to propose the following strategy for making changes to the regulation of the heat load of consumers.

1. For the transition period, enter a temperature schedule of 150-70 °C with a “cutoff” of 115 °C. With this schedule, the consumption of network water in the heating network for heating and ventilation needs should be maintained at the existing level corresponding to the design value, or with a slight excess, based on the performance of the installed network pumps. In the range of outside air temperatures corresponding to the “cut-off”, consider the calculated heating load of consumers to be reduced in comparison with the design value. The reduction in heating load is attributed to the reduction of thermal energy costs for ventilation, based on ensuring the required average daily air exchange of residential multi-apartment buildings according to modern standards at the level of 0.35 h -1.

2. Organize work to clarify the loads of heating systems of buildings by developing energy passports for residential buildings, public organizations and enterprises, paying attention, first of all, to the ventilation load of buildings, which is included in the load of heating systems, taking into account modern regulatory requirements on air exchange of premises. For this purpose, it is necessary for houses of different storeys, first of all, standard series perform a calculation of heat losses, both transmission and ventilation in accordance with modern requirements regulatory documentation of the Russian Federation.

3. Based on full-scale tests, take into account the duration of characteristic operating modes of ventilation systems and the non-simultaneity of their operation for different consumers.

4. After clarifying the heat loads of consumer heating systems, develop a schedule for regulating the seasonal load of 150-70 °C with a “cut-off” at 115 °C. The possibility of switching to the classic schedule of 115-70 °C without “cutting” with high-quality regulation should be determined after specifying the reduced heating loads. The temperature of the return network water should be clarified when developing a reduced schedule.

5. Recommend to designers, developers of new residential buildings and repair organizations performing major renovation old housing stock, the use of modern ventilation systems that make it possible to regulate air exchange, including mechanical ones with systems for recovering thermal energy from polluted air, as well as the introduction of thermostats to regulate the power of heating devices.

Literature

1. Sokolov E.Ya. Heating and heating networks, 7th ed., M.: MPEI Publishing House, 2001.

2. Gershkovich V.F. “One hundred and fifty... Is it normal or is it too much? Reflections on the parameters of the coolant…” // Energy saving in buildings. – 2004 - No. 3 (22), Kyiv.

3. Internal sanitary installations. At 3 o'clock. Part 1 Heating / V.N. Bogoslovsky, B.A. Krupnov, A.N. Scanavi et al.; Ed. I.G. Staroverova and Yu.I. Schiller, - 4th ed., revised. and additional - M.: Stroyizdat, 1990. -344 p.: ill. – (Designer's Handbook).

4. Samarin O.D. Thermophysics. Energy saving. Energy efficiency / Monograph. M.: ASV Publishing House, 2011.

6. A.D. Krivoshein, Energy saving in buildings: translucent structures and ventilation of premises // Architecture and construction of the Omsk region, No. 10 (61), 2008.

7. N.I. Vatin, T.V. Samoplyas “Ventilation systems for residential premises of apartment buildings”, St. Petersburg, 2004.

Most city apartments are connected to the central heating network. The main source of heat in large cities is usually boiler houses and thermal power plants. A coolant is used to provide heat in the house. As a rule, this is water. It is heated to a certain temperature and fed into the heating system. But the temperature in the heating system can be different and is related to the temperature of the outside air.

To effectively provide heat to city apartments, regulation is necessary. Observe set mode heating is helped by the temperature graph. What is a heating temperature schedule, what types are there, where is it used and how to draw it up - the article will tell you about all this.

The temperature graph is understood as a graph that shows the required water temperature in the heating system depending on the level of outside air temperature. Most often, the heating temperature schedule is determined for central heating. According to this schedule, heat is supplied to city apartments and other objects that are used by people. This schedule allows you to maintain optimal temperature and save heating resources.

When is a temperature chart needed?

In addition to central heating, the schedule is widely used in domestic autonomous heating systems. In addition to the need to regulate the temperature in the room, the schedule is also used to provide safety measures when operating household heating systems. This is especially true for those who install the system. Since the choice of equipment parameters for heating an apartment directly depends on the temperature schedule.

Based on the climatic conditions and temperature schedule of the region, a boiler and heating pipes are selected. The power of the radiator, the length of the system and the number of sections also depend on the temperature established by the standard. After all, the temperature of the heating radiators in the apartment must be within the standard limits. ABOUT technical specifications cast iron radiators can be read.

What are the temperature charts?

Schedules may vary. The standard temperature of the apartment heating radiators depends on the chosen option.

The choice of a specific schedule depends on:

1. climate of the region;
2. boiler room equipment;
3. technical and economic indicators of the heating system.

There are graphs for one- and two-pipe heat supply systems.

The heating temperature graph is indicated by two numbers. For example, the heating temperature graph 95-70 is deciphered as follows. For supporting desired temperature air in the apartment, the coolant should enter the system at a temperature of +95 degrees, and exit at a temperature of +70 degrees. Typically, this type of graph is used for autonomous heating. All old houses up to 10 floors high are designed for a heating schedule of 95-70. But if the house has a large number of floors, then a heating temperature schedule of 130-70 is more suitable.

In modern new buildings, when calculating heating systems, the 90-70 or 80-60 schedule is most often adopted. True, another option may be approved at the discretion of the designer. The lower the air temperature, the higher the temperature of the coolant entering the heating system. The temperature schedule is selected, as a rule, when designing the heating system of a structure.

Features of scheduling

Temperature chart indicators are developed based on the capabilities of the heating system, heating boiler, and temperature changes outside. By creating a temperature balance, you can use the system more carefully, which means it will last much longer. Indeed, depending on the materials of the pipes and the fuel used, not all devices are and are not always able to withstand sudden temperature changes.

When choosing the optimal temperature, you are usually guided by the following factors:

It should be noted that the temperature of the water in the central heating radiators should be such that it will allow the building to warm up well. For different rooms Various normative values ​​have been developed. For example, for a residential apartment the air temperature should not be less than +18 degrees. In kindergartens and hospitals this figure is higher: +21 degrees.

When the temperature of the heating radiators in the apartment is low and does not allow heating the room to +18 degrees, the owner of the apartment has the right to contact utility service to improve heating efficiency.

Since the room temperature depends on the season and climatic conditions, the temperature standard for heating radiators may be different. The heating of water in the heating system of a building can vary from +30 to +90 degrees. When the water temperature in the heating system is above +90 degrees, then decomposition begins paint coating, dust. Therefore, heating the coolant above this mark is prohibited by sanitary standards.

It must be said that the calculated outside air temperature for heating design depends on the diameter of the distribution pipelines, the size heating devices and coolant flow in the heating system. There is a special table of heating temperatures that makes it easier to calculate the schedule.

The optimal temperature in heating radiators, the norms of which are set according to the heating temperature schedule, allows you to create comfortable conditions residence. You can find out more about bimetallic heating radiators.

The temperature schedule is set for each heating system.

Thanks to it, the temperature in the home is maintained at an optimal level. Schedules may vary. Many factors are taken into account to develop them. Any schedule must be approved by an authorized city agency before being put into practice.

The temperature graph represents the dependence of the degree of heating of water in the system on the temperature of the cold outside air. After the necessary calculations, the result is presented in the form of two numbers. The first means the water temperature at the entrance to the heating system, and the second at the exit.

For example, the entry 90-70ᵒС means that under given climatic conditions, to heat a certain building, the coolant at the entrance to the pipes will need to have a temperature of 90ᵒС, and at the exit 70ᵒС.

All values ​​are presented for 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 standards, the internal temperature for residential premises is 20ᵒC. The schedule will ensure the correct supply of coolant to the heating pipes. This will avoid overcooling of the premises and waste of resources.

The need to perform constructions and calculations

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

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

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

Methods for regulating temperature in a heating system

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

• quantitative;
• quality;
• temporary.

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

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

Types of charts

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

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

The adjusted schedule is also intended for networks operating for both heating and heating. This takes into account heat losses as the coolant passes through the pipes to the consumer.

Drawing up a temperature chart

The drawn straight line depends on the following values:

• normalized indoor air temperature;
• outside air temperature;
• degree of heating of the coolant when entering the heating system;
• degree of heating of the coolant at the exit from the building networks;
• degree of heat transfer from heating devices;
• thermal conductivity of external walls and total heat losses of the building.

To perform a competent calculation, it is necessary to calculate the difference between the water temperatures in the forward and return pipes Δt. The higher the value in a straight pipe, the better the heat transfer of the heating system and the higher the indoor temperature.

In order to rationally and economically use the coolant, it is necessary to achieve the minimum possible value of Δt. This can be achieved, for example, by carrying out work on additional insulation of the external structures of the house (walls, coverings, ceilings above a cold basement or technical underground).

Heating mode calculation

First of all, it is necessary to obtain all the initial data. Standard values ​​of external and internal air temperatures are adopted 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 losses of the building

The initial data in this case will be:

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

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

Thermal losses of walls are calculated using the formula:

Q = F*(1/R 0)*(t indoor air -t outdoor air)

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

Battery Surface Power Calculation

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

P ud = P max /F act

Coolant temperature calculation

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

Carrying out calculations using this method is quite difficult. To perform competent calculations, it is best to use special programs.

For each building, this calculation is performed individually. management company. To approximately determine the water entering the system, you can use existing tables.

1. For large heat energy suppliers, coolant parameters are used 150-70ᵒС, 130-70ᵒС, 115-70ᵒС.
2. For small systems parameters apply to several apartment buildings 90-70ᵒС (up to 10 floors), 105-70ᵒС (over 10 floors). A schedule of 80-60ᵒC can also be adopted.
3. When settling in autonomous system heating for individual house It is enough to control the degree of heating using sensors; you don’t need to build a schedule.

The measures taken make it possible to determine the parameters of the coolant in the system at a certain point in time. By analyzing the coincidence of the parameters with the graph, you can check the efficiency of the heating system. The temperature chart table also indicates the degree of load on the heating system.