Temperature chart 95 70. Temperature chart of the heating system

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

1. The problem of reducing the design temperature schedule for regulating heat supply systems on a national scale

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 you know, closed and open centralized heating systems in the cities of the USSR were designed using high-quality regulation with a temperature schedule for regulating the seasonal load of 150-70 ° C. Such temperature graph it was widely used both for thermal power plants and for district boiler houses. But, already starting from the end of the 70s, significant deviations of the network water temperatures appeared in the actual control schedules from their design values at low temperatures ah outside air. Under the design conditions for the outside air temperature, the water temperature in the supply heating lines decreased from 150 ° С to 85 ... 115 ° С. The lowering of the temperature schedule by the owners of heat sources was usually formalized as work according to the design schedule of 150-70 ° С with a "cut-off" at a low temperature of 110 ... 130 ° С. At lower temperatures of the coolant, 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 calculation justifications 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 that are dictated by the balance energy ratios. In connection with a 2-fold decrease in the calculated temperature difference of the supply water while maintaining the heat load of heating and ventilation, it is necessary to ensure an increase in the flow of supply water for these consumers also by 2 times. Corresponding pressure losses through the network water in the heating network and in the heat exchange equipment of the heat source and heat points with a quadratic law of resistance will increase by 4 times. The required increase in the power of the network pumps should occur 8 times. Obviously, neither throughput heating networks designed for the schedule of 150-70 ° C, nor the installed network pumps will not allow the delivery of the heat carrier to consumers with a double flow rate in comparison with the design value.

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

The ban on the use of heat supply control schedules for heating networks with "cut-off" by temperatures, given in clause 7.11 of SNiP 41-02-2003 "Heating networks", could not affect the widespread practice of its use. In the updated version of this document SP 124.13330.2012, the mode with "cut-off" in temperature is not mentioned at all, that is, there is no direct prohibition on this method of regulation. This means that such methods of seasonal load regulation should be chosen, which will solve the main task - to ensure the normalized temperatures in the premises and the normalized water temperature for the needs of hot water supply.

To the approved List of national standards and codes of practice (parts of such standards and codes of practice), as a result of which, on a mandatory basis, compliance with the requirements is ensured Federal law dated 30.12.2009 No. 384-FZ "Technical Regulations on the Safety of Buildings and Structures" (Resolution of the Government of the Russian Federation dated 26.12.2014 No. 1521), the revisions of SNiP were included after updating. This means that the use of “cut-off” temperatures today is a completely legal measure, both from the point of view of the List of national standards and codes of rules, and from the point of view of the updated version of the profile SNiP “Heating networks”.

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

In the 90s, the deterioration of heating networks, fittings, compensators, as well as the inability to provide the necessary parameters on heat sources due to the state of the heat exchange equipment, were considered as weighty reasons that explained the radical decrease in the design temperature schedule. Despite the large volumes renovation works carried out constantly in heating networks and 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 the projects of 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 supplying heating line of the heating network during the entire heating period in strict accordance with the design, and not the actual temperature control schedule.

At present, the country is developing en masse heat supply schemes for cities and settlements, in which the design control schedules 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 provide such schedules in practice, there is no at least understandable justification for the possibility of providing the connected heat load at low outdoor temperatures under conditions of real regulation of the seasonal heat load.

Such a gap between the declared and actual temperatures of the heat carrier 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 real situation with the hydraulic mode of operation of heating networks and with the microclimate of the heated premises at the design temperature of the outside air. The actual situation is such that, despite a significant decrease in the temperature schedule, while ensuring the design flow of network water in the heating systems of cities, 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 the standard temperatures in the premises. 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, proceeding from the provision of the requirements of modern regulatory documents, or a “cut off” of the temperature graph at 115 ° C, or a new temperature graph of 115-70 (60) ° C with a qualitative regulation of the seasonal load?

This problem, naturally, constantly attracts everyone's attention. Therefore, publications appear in periodicals, which provide answers to the questions posed and provide recommendations for closing the gap between the design and actual parameters of the heat load regulation 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 vividly and clearly in the article by V.F. ...

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 in line with the lowered temperature schedule have not been successful. Rather, they contributed to the hydraulic deregulation of the heating network, as a result of which the consumption of network water between consumers was redistributed disproportionately to their heat loads.

At the same time, while maintaining the design flow in the network and reducing the temperature of the water in the supply line, even at low outdoor temperatures, in a number of cases, it was possible to ensure the indoor temperature at an acceptable level. The author explains this fact by the fact that in the heating load, a very significant part of the power falls on the heating of fresh air, which ensures the normative air exchange of the premises. Real air exchange on cold days is far from the normative value, since it cannot be provided only by opening the vents and sashes of window blocks or double-glazed windows. The article emphasizes that Russian air exchange rates are several times higher than those of Germany, Finland, Sweden, and the United States. It is noted that in Kiev, the decrease in the temperature schedule due to the "cut-off" from 150 ° C to 115 ° C was implemented and had no negative consequences. Similar work has been done in the heat networks of Kazan and Minsk.

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

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

Increasing the water consumption in the network in order to maintain the air temperature in the premises;

Reducing the power of the heating system by reducing air exchange for the design water consumption 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 consumption in the network while ensuring the calculated air temperature in the premises.

2. Initial data for analysis

As the initial data, it is assumed that there is a heat supply source with a dominant heating and ventilation load, a two-pipe heating network, a central heating station and an IHP, heating devices, air heaters, and water taps. The type of heat supply system is not critical. It is assumed that the design parameters of all links of the heat supply system provide normal work heat supply systems, that is, in the premises of all consumers, the design temperature tp = 18 ° C is set, subject to the temperature schedule of the heating network of 150-70 ° C, the design value of the network water consumption, standard air exchange and quality regulation of seasonal load. The design temperature of the outside air is equal to the average temperature of a cold five-day period with a safety factor of 0.92 at the time of the creation of the heat supply system. The mixing ratio of elevator units is determined by the generally accepted temperature schedule for regulating heating systems of 95-70 ° C and is equal to 2.2.

It should be noted that in the updated version of SNiP “Construction 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 revision of the SNiP 23-01-99 document.

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

The work under new conditions of the heat supply system, created over tens of years according to the standards modern for the construction period, is considered. Design temperature schedule for quality regulation of seasonal load 150-70 ° С. 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 links of the heat supply system, its behavior is determined at a maximum water temperature in the supply line of 115 ° C at a design temperature of the outside air, mixing coefficients of elevator nodes of 2.2.

One of the defining 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 150-70 ° C and the declared load of heating, ventilation;

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

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

3.1. Reduction of indoor air temperature while maintaining the connected heat loads

Let us determine how the average temperature in the rooms will change at the temperature of the supply water in the supply line to 1 = 115 ° С, the design consumption of the supply water for heating (we will assume that the entire heating load, since the ventilation load is of the same type), based on the design schedule 150-70 ° С, at an outside air temperature t n.o = -25 ° С. We assume that at all elevator nodes the mixing ratios u are calculated and are equal to

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

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 rooms, G o is the estimated flow rate of network water entering the elevator nodes, G p is the estimated flow rate of water entering into heating devices, G p = (1 + u) G o, s is the specific mass isobaric heat capacity of water, is the average design value of the heat transfer coefficient of the building, 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 supply water in the supply line t o 1 = 115 ° C, while maintaining the design air exchange, the average air temperature in the premises decreases to the value of t in. The corresponding system of equations for the design conditions for the outside air will have the form

, (3)

where n is the exponent in the criterional dependence of the heat transfer coefficient of heating devices on the average temperature head, see, table. 9.2, page 44. For the most common heating devices in the form of cast-iron sectional radiators and steel panel convectors of the RSV and RSG type, 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 the given design values of the heat supply system parameters

Equation (5), taking into account (3) for a given temperature of direct water under design conditions, makes it possible to obtain a relation for determining the air temperature in rooms:

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

The relative thermal power of the heating system is

Consequently, when the temperature of the direct network water changes from 150 ° C to 115 ° C, the average air temperature in the premises decreases from 18 ° C to 8.7 ° C, 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 ° С, ° С.

The performed calculation corresponds to the case when the outside air flow rate during the operation of the ventilation and infiltration system corresponds to the design standard values up to the outside 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 outside temperatures, the consumption of cold air entering the premises, especially after practically complete replacement window blocks for double-glazed windows is far from the standard value. Therefore, the air temperature in residential premises is in fact much higher than a certain value of t in = 8.7 ° C.

3.2 Determination of the capacity of the heating system by reducing the ventilation of the air in the premises at the estimated flow rate of network water

Let us determine how much it is necessary to reduce the consumption of heat energy for ventilation in the considered non-design mode of reduced temperature of the heating network network water in order for the average air temperature in the premises to remain at the standard level, that is, t in = t in.p = 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), similarly to the previous case, gives the following relationships for the temperatures of various water flows:

The equation for a given temperature of direct water under design conditions based on the outside air temperature makes it possible to find a reduced relative load of the heating system (only the capacity of the ventilation system has been reduced, heat transfer through the outer fences is exactly preserved):

The solution to this equation is = 0.706.

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

The calculated values of water temperatures for the accepted deviation from the temperature graph are ° С, ° С.

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

Let us determine how the flow of network water in the heating network for heating needs should increase when the temperature of the network water in the supply line drops to 1 = 115 ° С under design conditions for the outdoor air temperature t n.o = -25 ° С, so that the average temperature in indoor air remained at the standard level, that is, t in = t in p = 18 ° C. Ventilation of the premises is within 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 flow rate of network water up to G o y and the flow of water through the heating system G ny = G oy (1 + u) with a constant value of the mixing ratio of the elevator nodes u = 2.2. For clarity, we reproduce in this system the equations (1)

From (1), (2 "), (3 ') follows the system of equations of the intermediate form

The solution to the reduced system is as follows:

° C, t o 2 = 76.5 ° C,

So, when the temperature of the direct network water changes from 150 ° C to 115 ° C, the preservation of the average air temperature in the premises at the level of 18 ° C is possible due to an increase in the consumption of network water in the supply (return) line of the heating network for the needs of heating and ventilation systems in 2 , 08 times.

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

3.5 Decrease in the capacity of the heating system by reducing the ventilation of the air in the premises in conditions of increased consumption of network water

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

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

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

The relative decrease in the thermal power of the heating system is

. (3’’)

From (1), (2 '' ''), (3 '') the decision follows

For the given values of the heat supply system parameters u = 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 of t n.o_ = -22 ° C. The relative thermal power of the heating system is

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

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

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

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

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

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

Let the declared load of the heating system, created in recent decades, be equal. This load corresponds to the design temperature of the outside air, actual during the construction period, taken for definiteness t n.d = -25 ° С.

Below is an estimate of the actual reduction in the declared design heating load due to various factors.

An increase in the design outside air temperature to -22 ° С reduces the design heating load to the value (18 + 22) / (18 + 25) x100% = 93%.

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

1. Replacement of window blocks with double-glazed windows, which took place almost everywhere. The share of transmission losses of heat energy through the windows is about 20% of the total heating load. Replacement of window blocks with double-glazed windows led to an increase in thermal resistance from 0.3 to 0.4 m 2 ∙ K / W, respectively, 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 early 2000s is about 40 ... 45%, later - about 50 ... 55%. Let's take the average share of the ventilation component in the heating load in the amount of 45% of the declared heating load. It corresponds to an air exchange rate of 1.0. By modern standards STO maximum air exchange rate is at the level of 0.5, the average daily rate of air exchange 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 value:

x100% = 70.75%.

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

4. Allowance for an increase in the design outdoor temperature will lead to an even greater drop in the design heating load.

5. The performed estimates show that the specification of the heat load of heating systems can lead to its reduction by 30 ... 40%. Such a decrease in the heating load makes it possible to expect that, while maintaining the design flow rate of network water, the calculated air temperature in the premises can be ensured by implementing a “cut-off” of the direct water temperature at 115 ° C for low outdoor air temperatures (see results 3.2). This can be argued with even greater grounds if there is a reserve in the flow rate of network water at the heat source of the heat supply system (see results 3.4).

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

It should be borne in mind that quality regulation seasonal load is not sustainable in terms of the distribution of heat power among heating devices for vertical one-pipe systems heating. Therefore, in all the calculations given above, while ensuring the average design air temperature in the rooms, there will be some change in the air temperature in the rooms along the riser during the heating season at different temperatures of the outside air.

5. Difficulties in the implementation of the normative air exchange of premises

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, 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-shielding properties of external fences, primarily walls, have significantly increased (2 ... 3 times).

From the practice of developing energy certificates for residential buildings, it follows that for buildings constructed from the 50s to 80s of the last century in the central and north-western 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, the provision of standard air exchange has become even more bigger problem... This is due to a tenfold decrease in uncontrolled infiltration through the cracks and the fact that frequent ventilation by opening the sashes of the windows, which alone can provide the normative air exchange, in fact does not occur.

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

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

The calculation of the ventilation system of a residential building carried out by SPbSPU employees showed the following. Natural ventilation in the mode of free air flow, on average, almost 50% of the time per year is less than the calculated one (the section of the exhaust duct was designed according to the current ventilation standards for apartment buildings for the conditions of St. Petersburg for standard air exchange for outside temperature+5 ° С), in 13% of the time 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 the standard air exchange; at outside air temperatures of more than + 5 ° C, the air exchange will be lower than the standard, if the fan is not used.

6. Evolution of regulatory requirements for air exchange in premises

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

Consider 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 a kitchen with electric stoves, the air exchange rate was 3, but not less than 60 m 3 / h, for a kitchen with 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. Design temperature of living rooms + 18 ° С, kitchen + 15 ° С.

In SNiP II-L.1-71, part II, section L, chapter 1, which were in force until July 1986, similar norms are indicated, but for a kitchen with electric stoves, the air exchange rate of 3 is excluded.

In SNiP 2.08.01-85, in effect until January 1990, the air exchange rates for living rooms were 3 m 3 / h per 1 m 2 of the area of the rooms, for a kitchen without specifying the type of plates 60 m 3 / h. Despite the different standard temperatures in living quarters and in the kitchen, it is proposed to take the temperature of the internal air + 18 ° С for heat engineering calculations.

In SNiP 2.08.01-89, which were in effect until October 2003, the air exchange rates are the same as in SNiP II-L.1-71, part II, section L, chapter 1. An indication of the internal air temperature of +18 ° is preserved WITH.

In the current SNiP 31-01-2003, new requirements appear, given in 9.2-9.4:

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

Table 9.1

Premises	Multiplicity or magnitude air exchange, m 3 per hour, not less
Premises	in non-working	in mode service
Bedroom, common, children's room	0,2	1,0
Library, cabinet	0,2	0,5
Pantry, linen, dressing room	0,2	0,2
Gym, billiard room	0,2	80 m 3
Laundry, 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, restroom, combined bathroom	0,5	25 m 3
Sauna	0,5	10 m 3 for 1 person
Elevator engine room	-	By calculation
Parking	1,0	By calculation
Waste collection chamber	1,0	1,0

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

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

9.4 The heating and ventilation system of the building must be designed to provide the premises during the heating period with the internal air temperature within optimal parameters established by GOST 30494, with the design parameters of the outside air for the corresponding construction areas.

From this it can be seen that, firstly, the concepts of a room service mode and a non-operating mode appear, during the operation of 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 area of an apartment, the air exchange rates under different modes differ by a factor of 5. The air temperature in the premises when calculating the heat losses of the projected building should be taken at least 20 ° C. In residential premises, the rate of air exchange is normalized, regardless of the area and the number of residents.

The updated edition of SP 54.13330.2011 partially reproduces the information SNiP 31-01-2003 in the original edition. Air exchange rates for bedrooms, dormitories, children's rooms at total area apartments for one person less than 20 m 2 - 3 m 3 / h per 1 m 2 of the area of the rooms; the same with the total area of the apartment for one person 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 of the modes, determine the air flow in different rooms during each mode and then calculate the average hourly demand of the apartment for fresh air and then at home in general. Multiple 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 irregularities in 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 load of the house for the needs of ventilation and to a non-additive addition of this load for different consumers.

It is possible to draw an analogy with the non-simultaneous use of the DHW load by consumers, which obliges to introduce the hourly unevenness factor when determining the DHW load for a heat source. As you know, its value for a significant number of consumers in the regulatory documentation is taken equal to 2.4. A similar value for the ventilation component of the heating load suggests that the corresponding total load will also in fact 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 off-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 you to focus on the average daily values of thermal energy consumption for air heating. Moreover, in most heating systems there are no thermostats that maintain the air temperature in the premises. It is also known that the central regulation of the temperature of the network water in the supply line for heat supply systems is carried out according to the outside air temperature, averaged over a period of about 6-12 hours, and sometimes for a longer 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 calculated 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 the design of 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 listed above.

The standards of organizations that regulate the norms of air exchange in the premises of multi-apartment residential buildings have been developed and published. For example, STO NPO AVOK 2.1-2008, STO SRO NP SPAS-05-2013, Energy saving in buildings. Calculation and design of residential ventilation systems apartment buildings(Approved by the general meeting of the SRO NP SPAS on 03/27/2014).

Basically, in these documents, the cited norms correspond to SP 54.13330.2011 with some reductions in 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 in a kitchen of this type, air exchange is allowed 0 , 5 h -1, while 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:

The total area of the apartment is F total = 82.29 m 2;

Living area F lived = 43.42 m 2;

Kitchen area - F kx = 12.33 m 2;

Bathroom area - F vn = 2.82 m 2;

Restroom area - F ub = 1.11 m 2;

Room height h = 2.6 m;

The kitchen has an electric stove.

Geometric characteristics:

The volume of heated premises V = 221.8 m 3;

The volume of living quarters V lived = 112.9 m 3;

The volume of the kitchen is V kx = 32.1 m 3;

The volume of the restroom V ub = 2.9 m 3;

The volume of the bathroom V vn = 7.3 m 3.

From the above calculation of air exchange it follows that the ventilation system of the apartment must provide the calculated air exchange in the service mode (in the design operation) - L tr work = 110.0 m 3 / h; in idle mode - L tr work = 22.6 m 3 / h. The given air flow rates correspond to the air exchange rate of 110.0 / 221.8 = 0.5 h -1 for the service 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 the transmission losses of heat 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 air exchange rate of apartment buildings of 0.35 h - one .

Analysis of the energy passports of a residential building, developed in accordance with SNiP 23-02-2003 "Thermal protection of 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, not contradicting the requirements of modern service stations.

It is necessary to clarify the heating load of buildings built according to standard designs, based on the reduced average value of the air exchange rate, which will correspond to the existing Russian standards and will make it possible to approach the standards of a number of EU countries and the United States.

7. Justification for lowering the temperature schedule

Section 1 shows that the temperature graph is 150-70 ° C due to the actual impossibility of its use in modern conditions should be lowered or modified by justifying the temperature cutoff.

The above calculations of various modes of operation of the heat supply system in off-design conditions allow us to propose the following strategy for making changes in 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 such a schedule, the flow of network water in the heating network for heating and ventilation needs should be kept at the existing level, corresponding to the design value, or with a slight excess, based on the capacity of the installed network pumps. In the range of outside air temperatures corresponding to the "cut-off", consider the calculated heating load of consumers reduced in comparison with the design value. The decrease in the heating load is attributed to the reduction of heat energy consumption for ventilation, based on the provision of the necessary average daily air exchange in 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 in buildings by developing energy certificates 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 for air exchange in premises. For this purpose, it is necessary for houses of different storeys, first of all, of standard series, to calculate heat losses, both transmission and ventilation in accordance with the modern requirements of the regulatory documents of the Russian Federation.

3. On the basis of field tests, take into account the duration of the characteristic modes of operation of ventilation systems and the non-simultaneity of their operation for different consumers.

4. After clarifying the heat loads of the heating systems of consumers, develop a schedule for regulating the seasonal load of 150-70 ° C with a cutoff by 115 ° C. The possibility of switching to the classic 115-70 ° C schedule without “cutting off” with quality control should be determined after specifying the reduced heating loads. The temperature of the return water supply should be specified when developing a reduced schedule.

5. Recommend to designers, developers of new residential buildings and repair organizations performing overhaul old housing stock, application modern systems ventilation, allowing to regulate air exchange, including mechanical ones with systems for recuperating the thermal energy of polluted air, as well as the introduction of thermostats to adjust the power of heating devices.

Literature

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

2. Gershkovich V.F. “One hundred and fifty ... Normal or overkill? Reflections on the parameters of the heat carrier ... ”// Energy saving in buildings. - 2004 - No. 3 (22), Kiev.

3. Internal sanitary facilities. At 3 o'clock Part 1 Heating / V.N. Bogoslovsky, B.A. Krupnov, A.N. Skanavi and others; Ed. I.G. Staroverov and Yu.I. Schiller, - 4th ed., Revised. and add. - M .: Stroyizdat, 1990.-344 p .: ill. - (Designer handbook).

4. Samarin O.D. Thermophysics. Energy saving. Energy efficiency / Monograph. Moscow: 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

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

Heating and ventilation heat loads unambiguously depend on the outside air temperature tн.в. Therefore, it is necessary to regulate the heat release in accordance with changes in the load. You use mainly central regulation carried out at CHP plants, supplemented by local automatic regulators.

With central regulation, it is possible to apply either quantitative regulation, which is reduced to a change in the flow of network water in the supply line at a constant temperature, or qualitative, in which the flow of water 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 heating systems across floors. Therefore, quality control is usually used, for which the temperature graphs of the heating network for the heating load must be calculated depending on the outside temperature.

The temperature schedule 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 outside temperature tn.o. So, a graph of 150-70 ° C means that at a calculated outside temperature tн.o. the maximum (calculated) temperature in the supply line is τ1 = 150 and in the return line τ2 - 70 ° С. 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 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, which excludes water boiling, and, consequently, 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 subscribers are connected 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 supply water in the supply line leads to a decrease in the consumption of the supply water, which reduces the cost of the heating network, but also reduces the generation of electricity from thermal consumption. The choice of the temperature schedule for the heat supply system must be confirmed by a technical and economic calculation for the minimum of the reduced costs for the CHP and the heating network.

Heat supply to the CHPP-2 industrial site is carried out according to a temperature schedule of 150/70 ° C with a cutoff of 115/70 ° C, in connection with which the temperature of the network water is automatically controlled only up to the outside air temperature "- 20 ° C". Supply water consumption is too high. An excess of the actual flow rate of the heating system over the calculated one leads to an excessive consumption of electrical energy for pumping the coolant. The temperature and pressure in the return pipe does not correspond to the temperature schedule.

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 the TMUP TTS, the discharge from the heat supply systems due to the lack of the required pressure drop among consumers and leaks in the heating surfaces of hot water heaters, there is an increased consumption of make-up water at the CHP, exceeding the calculated value by 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 heating water temperatures on the outside air temperature

Table 6.1.

Temperature value

Outside air

filing master ali

After the elevator

reverse master

Outside air

lodging master

After the elevator

In back th master ali

What patterns obey the changes in the temperature of the coolant in the systems central heating? What is it - the temperature graph of the heating system 95-70? How to bring the heating parameters in line with the schedule? Let's try to answer these questions.

What it is

Let's start with a couple of abstract theses.

With a change in weather conditions, the heat loss of any building changes after them... In freezing conditions, in order to maintain a constant temperature in an apartment, much more heat energy is required than in warm weather.

Let's clarify: heat consumption is determined not by the absolute value of the air temperature outside, but by the delta between the street and the interior.
So, at + 25C in the apartment and -20 in the yard, the heat costs will be exactly the same as at +18 and -27, respectively.

Heat flow from heater at a constant temperature of the coolant will also be constant.
A drop in temperature in the room will slightly increase it (again, due to an increase in the delta between the coolant and the air in the room); however, this increase will be categorically insufficient to compensate for the increased heat loss through the building envelope. Simply because the current SNiP limits the lower temperature threshold in the apartment to 18-22 degrees.

An obvious solution to the problem of increasing losses is to increase the temperature of the coolant.

Obviously, its growth should be proportional to the decrease in outdoor temperature: the colder it is outside the window, the greater the heat loss will have to be compensated. Which, in fact, brings us to the idea of creating a certain table of agreement of both values.

So the graph temperature system heating is a description of the dependence of the temperatures of the supply and return pipelines on the current weather outside.

How it works

There are two different types charts:

For heating networks.
For indoor heating system.

To clarify the difference between the two, it is probably worth starting with a short excursion how central heating works.

CHP - heating networks

The function of this bundle is to heat the coolant and deliver it to the end consumer. The length of heating mains is usually measured in kilometers, the total surface area is in thousands and thousands of square meters. Despite the measures for thermal insulation of pipes, heat losses are inevitable: after passing the way from the CHP or boiler house to the border of the house, the process water will have time to partially cool down.

Hence - the conclusion: in order for it to reach the consumer, while maintaining an acceptable temperature, the supply of the heating main at the exit from the CHPP should be as hot as possible. The limiting factor is the boiling point; however, as the pressure rises, it shifts towards an increase in temperature:

Pressure, atmospheres	Boiling point, degrees Celsius
1	100
1,5	110
2	119
2,5	127
3	132
4	142
5	151
6	158
7	164
8	169

Typical pressure in the supply pipe of the heating main is 7-8 atmospheres. This value, even taking into account the head loss during transportation, allows you to start the heating system in houses up to 16 floors high without additional pumps. At the same time, it is safe for routes, risers and connections, mixer hoses and other elements of heating and hot water systems.

With a certain margin, the upper limit of the supply temperature is taken equal to 150 degrees. The most typical heating temperature curves for heating mains lie in the range 150/70 - 105/70 (flow and return temperatures).

House

There are a number of additional limiting factors in a home heating system.

The maximum temperature of the coolant in it cannot exceed 95 C for a two-pipe and 105 C for.

By the way: in preschool educational institutions the restriction is much stricter - 37 C.
The price of lowering the supply temperature is an increase in the number of radiator sections: in the northern regions of the country, the premises of groups in kindergartens are literally surrounded by them.

The delta of temperatures between the supply and return pipelines, for obvious reasons, should be as small as possible - otherwise the temperature of the batteries in the building will vary greatly. This implies fast circulation of the coolant.
However, too fast circulation through house system heating will lead to the fact that the return water will return to the line with an exorbitant high temperature, which is unacceptable due to a number of technical restrictions in the operation of the CHPP.

The problem is solved by installing one or several elevator units in each house, in which return flow is added to the stream of water from the supply pipeline. The resulting mixture, in fact, ensures the rapid circulation of a large volume of the coolant without overheating the return pipeline of the route.

For in-house networks, a separate temperature schedule is set, taking into account the operation of the elevator. For two-pipe circuits, a typical heating temperature schedule is 95-70, for one-pipe circuits (which, however, is rare in apartment buildings) - 105-70.

Climatic zones

The main factor that determines the scheduling algorithm is the estimated winter temperature. The table of coolant temperatures should be drawn up in such a way that the maximum values (95/70 and 105/70) at the peak of frost provide the corresponding SNiP temperature in the living quarters.

Let's give an example of an in-house schedule for the following conditions:

Heating devices - radiators with the supply of the coolant from the bottom up.
Heating - two-pipe, with.

The design temperature of the outside air is -15 C.

Outside air temperature, С	Feed, С	Return, С
+10	30	25
+5	44	37
0	57	46
-5	70	54
-10	83	62
-15	95	70

Nuance: when determining the parameters of the route and the internal heating system, the average daily temperature is taken.
If it is -15 at night and -5 in the daytime, -10C appears as the outside temperature.

And here are some calculated values winter temperatures for the cities of Russia.

City	Design temperature, С
Arkhangelsk	-18
Belgorod	-13
Volgograd	-17
Verkhoyansk	-53
Irkutsk	-26
Krasnodar	-7
Moscow	-15
Novosibirsk	-24
Rostov-on-Don	-11
Sochi	+1
Tyumen	-22
Khabarovsk	-27
Yakutsk	-48

In the photo - winter in Verkhoyansk.

Adjustment

If the management of the CHP and heating networks is responsible for the parameters of the route, then the responsibility for the parameters of the in-house network rests with the housing dwellers. A very typical situation is when, when residents complain about the cold in apartments, measurements show deviations from the schedule to the lower side. Slightly less often, it happens that measurements in the wells of thermal workers show an overestimated return temperature from the house.

How to bring the heating parameters in line with the schedule with your own hands?

Reaming the nozzle

With an underestimated mixture and return temperature, the obvious solution is to increase the diameter of the elevator nozzle. How it's done?

The instruction is at the service of the reader.

All valves or valves are closed in elevator unit(entrance, house and hot water supply).
The elevator is dismantled.
The nozzle is removed and reamed out by 0.5-1 mm.
The elevator is assembled and started up with air purging in the reverse order.

Tip: instead of paronite gaskets, you can put rubber gaskets on the flanges, cut to the size of the flange from the car camera.

An alternative is to install an elevator with an adjustable nozzle.

Suction suppression

In a critical situation (extreme cold and freezing apartments) the nozzle can be completely removed. To prevent the suction from becoming a jumper, it is muffled by a pancake made of steel sheet with a thickness of at least a millimeter.

Attention: this is an emergency measure used in extreme cases, since in this case the temperature of the radiators in the house can reach 120-130 degrees.

Differential adjustment

At elevated temperatures as a temporary measure until the end heating season the adjustment of the elevator differential with a gate valve is practiced.

The DHW is switched over to the flow line.
A pressure gauge is installed on the return line.
The inlet valve on the return pipeline closes completely and then gradually opens with pressure control according to a manometer. If you simply close the valve, the drawdown of the cheeks on the stem can stop and defrost the circuit. The difference is reduced by increasing the pressure on the return line by 0.2 atmospheres per day with daily temperature control.

Conclusion

Most of the city apartments are connected to the central heating network. The main source of heat in large cities usually there are boiler houses and CHP plants. A heating medium is used to provide heat in the house. As a rule, this is water. It is heated to a certain temperature and supplied to the heating system. But the temperature in the heating system can be different and is associated with the temperature indicators of the outside air.

In order to efficiently supply city apartments with heat, regulation is necessary. The temperature schedule helps to comply with the set heating mode. What is a heating temperature graph, what types of it are, where it is used and how to draw it up - the article will tell you about all this.

A temperature graph is understood as a graph that shows the required mode of water temperature in the heat supply system, depending on the level of the 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. Such a schedule allows you to maintain an optimal temperature and save heating resources.

When is a temperature chart needed?

In addition to district heating, the schedule is widely used in domestic autonomous heating systems. In addition to the need to adjust the temperature in the room, the schedule is also used in order to provide security measures for the operation of household heating systems. This is especially true for those who are installing the system. Since the choice of equipment parameters for heating an apartment directly depends on the temperature graph.

Based on the climatic features and the 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 set by the standard. After all, the temperature of the heating radiators in the apartment should be within the standard. About technical characteristics cast iron radiators can be read.

What temperature charts are there?

Graphs may vary. The standard for the temperature of the apartment heating batteries depends on the option chosen.

The choice of a specific schedule depends on:

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

Allocate graphs of one- and two-pipe system heat supply.

Designate the heating temperature graph with two digits. For example, the temperature graph of heating 95-70 is deciphered as follows. For supporting the right temperature air in the apartment, the coolant must enter the system with a temperature of +95 degrees, and exit at a temperature of +70 degrees. As a rule, such a schedule is used for autonomous heating. All old houses up to 10 floors are designed for heating schedule 95 70. But if the house has a large number of storeys, then the heating temperature schedule 130 70 is more suitable.

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

Features of scheduling

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

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

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

When the temperature of the heating batteries in the apartment is low and does not allow the room to warm up to +18 degrees, then the owner of the apartment has the right to contact the utility service to increase the efficiency of heating.

Since the temperature in the room depends on the season and climatic characteristics, the standard for the temperature of the radiators may be different. The heating of water in the heat supply system of the structure can vary from +30 to +90 degrees. When the temperature of the water in the heating system is higher than +90 degrees, then the decomposition of the paintwork and dust begins. Therefore, above this mark, heating the coolant is prohibited by sanitary standards.

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

The optimum temperature in the heating batteries, the norms of which are set according to the heating temperature schedule, allows you to create comfortable conditions accommodation. Learn more about bimetallic radiators heating can be found out.

The temperature schedule is set for each heating system.

Thanks to him, the temperature in the home is maintained at an optimal level. Graphs may vary. Many factors are taken into account for their development. Any schedule, before being put into practice, needs to be approved by the authorized institution of the city.

After installing the heating system, it is necessary to adjust temperature regime... This procedure must be carried out in accordance with existing standards.

The requirements for the temperature of the coolant are set out in the regulatory documents that establish the design, installation and use of engineering systems for residential and public buildings. They are described in the State Building Codes and Rules:

DBN (V. 2.5-39 Heating networks);
SNiP 2.04.05 "Heating, ventilation and air conditioning".

For the calculated supply water temperature, the figure is taken that is equal to the temperature of the water leaving the boiler, according to its passport data.

For individual heating, it is necessary to decide what the coolant temperature should be, taking into account the following factors:

The beginning and end of the heating season according to the average daily temperature outside +8 ° C for 3 days;
The average temperature inside heated premises of housing and communal and public importance should be 20 ° C, and for industrial buildings 16 ° C;
The average design temperature must comply with the requirements of DBN V.2.2-10, DBN V.2.2.-4, DSanPiN 5.5.2.008, SP No. 3231-85.

According to SNiP 2.04.05 "Heating, ventilation and air conditioning" (paragraph 3.20), the limit values of the coolant 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.

For calculation optimal performance special charts and tables can be used, in which norms are determined depending on the season:

With an average indicator outside the window of 0 ° C, the flow for radiators with different wiring is set at a level of 40 to 45 ° C, and the return temperature is from 35 to 38 ° C;
At -20 ° C, the feed is heated from 67 to 77 ° C, and the return rate should be from 53 to 55 ° C;
At -40 ° C outside the window for all heating devices set the maximum allowable values... On the supply line it is from 95 to 105 ° С, and on the return - 70 ° С.

Optimum values in an individual heating system

H2_2

Heating system helps to avoid many problems that arise with a centralized network, and the optimal temperature of the coolant can be adjusted in accordance with the season. In the case of individual heating, the concept of norms includes the heat transfer of the heating device per unit area of the room where this device is located. The thermal regime in this situation is ensured design features heating devices.

It is important to ensure that the heat carrier in the network does not cool below 70 ° C. An indicator of 80 ° C is considered optimal. WITH gas boiler it is easier to control heating, because manufacturers limit the possibility of heating the coolant to 90 ° C. Using sensors to regulate the gas supply, the heating of the coolant can be controlled.

It is a little more complicated 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. In this case, the control of heating of the coolant is rather arbitrary with high errors and is performed by rotary thermostats and mechanical dampers.

Electric boilers allow you to smoothly regulate the heating of the coolant from 30 to 90 ° C. They are equipped with an excellent overheating protection system.

One-pipe and two-pipe lines

The design features of a one-pipe and two-pipe heating network determine different norms for heating the coolant.

For example, for a single-pipe line, the maximum rate is 105 ° С, and for a two-pipe line - 95 ° С, while the difference between the return and supply should be respectively: 105 - 70 ° С and 95 - 70 ° С.

Coordination of the temperature of the coolant and the boiler

Regulators help to coordinate the temperature of the coolant and the boiler. These are devices that create automatic control and adjustment of the return and flow temperature.

The return temperature is dependent on the amount of fluid passed through it. The regulators cover the fluid supply and increase the difference between the return and the supply to the level that is needed, and the necessary indicators 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 the regulator. To reduce the heating of the supply, a "cold start" is used: that part of the liquid that passed through the network is again sent 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 network.

Ways to reduce heat loss

The above information will help to be used for correct calculation coolant temperature norms and will tell you how to determine the situations when you need to use the regulator.

But it is important to remember that the temperature in the room is influenced not only by the temperature of the coolant, outside air and the strength of the wind. 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, plastic windows will help reduce heat leakage. It also reduces heating costs.

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