Online calculator for calculating the heating temperature schedule. Temperature schedule of coolant supply to the heating system. Factors affecting battery temperature

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

What it is

Let's start with a couple of abstract points.

• As weather conditions change, the heat loss of any building changes along with them. In frosty weather, in order to maintain a constant temperature in the apartment, much more thermal energy is required than in warm weather.

Let us clarify: heat costs are 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, heat costs will be exactly the same as at +18 and -27, respectively.

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

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

Obviously, its increase should be proportional to the decrease in street temperature: the colder it is outside, the greater the heat loss will have to be compensated. Which, in fact, brings us to the idea of ​​creating a specific table for reconciling both values.

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

How everything works

There are two different types of charts:

1. For heating networks.
2. For indoor heating system.

To explain the difference between these concepts, it is probably worth starting with a brief excursion into 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 measured in thousands and thousands of square meters. Despite measures to insulate pipes, heat loss is inevitable: after traveling from the thermal power plant or boiler room to the border of the house, process water will have time to partially cool.

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 thermal power plant must be as hot as possible. The limiting factor is the boiling point; however, as the pressure increases, it shifts towards increasing temperature:

Pressure, atmosphere	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 pipeline of a heating main is 7-8 atmospheres. This value, even taking into account pressure losses during transportation, allows you to start a heating system in buildings 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 some margin, the upper limit of the supply temperature is taken to be 150 degrees. The most typical heating temperature curves for heating mains are in the range of 150/70 – 105/70 (supply 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 limit is much more stringent - 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, group rooms in kindergartens are literally surrounded by them.

• For obvious reasons, the temperature delta between the supply and return pipelines should be as small as possible - otherwise the temperature of the batteries in the building will vary greatly. This implies rapid circulation of the coolant.
  However, too fast circulation through the house heating system will lead to the return water returning to the route at an unreasonably high temperature, which is unacceptable due to a number of technical limitations in the operation of thermal power plants.

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

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

Climate zones

The main factor determining the scheduling algorithm is the estimated winter temperature. The coolant temperature table must be drawn up in such a way that the maximum values ​​(95/70 and 105/70) at the peak of frost provide the temperature in residential premises corresponding to SNiP.

Let's give an example of an intra-house graph for the following conditions:

• Heating devices - radiators with coolant supply from bottom to top.
• Heating is two-pipe, with .

• The estimated outside air temperature is -15 C.

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

A nuance: when determining the parameters of the route and the intra-house heating system, the average daily temperature is taken.
If it is -15 at night and -5 during the day, the outside temperature is -10C.

And here are some values ​​of calculated winter temperatures for Russian cities.

City	Design temperature, C
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

The photo shows winter in Verkhoyansk.

Adjustment

If the management of the thermal power plant and heating networks is responsible for the parameters of the route, then responsibility for the parameters of the intra-house network rests with the housing residents. A very typical situation is when, when residents complain about the cold in their apartments, measurements show deviations from the schedule downward. It happens a little less often that measurements in thermal wells show an elevated return temperature from the house.

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

Reaming the nozzle

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

Instructions are at the reader's disposal.

1. All valves or valves in the elevator unit (input, house and DHW) are closed.
2. The elevator is being dismantled.
3. The nozzle is removed and drilled 0.5-1 mm.
4. The elevator is assembled and started with air bleeding in the reverse order.

Advice: instead of paronite gaskets, you can put rubber gaskets on the flanges, cut to the size of the flange from a car inner tube.

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

Choke suppression

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

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 of the heating season, it is practiced to adjust the differential on the elevator using a valve.

1. The DHW switches to the supply pipe.
2. A pressure gauge is installed on the return line.
   
3. The inlet valve on the return pipeline is completely closed and then gradually opens with pressure controlled by a pressure gauge. If you simply close the valve, the subsidence of the cheeks on the rod can stop and defrost the circuit. The difference is reduced by increasing the return pressure by 0.2 atmospheres per day with daily temperature control.

Conclusion

Construct a schedule for central high-quality regulation of heat supply for a closed heat supply system based on the combined load of heating and hot water supply (increased or adjusted temperature schedule).

Accept the calculated temperature of the network water in the supply line t 1 = 130 0 C in the return line t 2 = 70 0 C, after the elevator t 3 = 95 0 C. Design outside air temperature for heating design tnro = -31 0 C. Design air temperature indoors tв= 18 0 С. The calculated heat flows are the same. Hot water temperature in hot water supply systems tgv = 60 0 C, cold water temperature t c = 5 0 C. Balance coefficient for hot water supply load a b = 1.2. The connection diagram for water heaters of hot water supply systems is two-stage sequential.

Solution. Let us first carry out the calculation and construction of a heating and domestic temperature graph with the temperature of the network water in the supply pipeline for the break point = 70 0 C. Values ​​of network water temperatures for heating systems t 01 ; t 02 ; t 03 will be determined using calculated dependencies (13), (14), (15) for outside air temperatures t n = +8; 0; -10; -23; -31 0 C

Let us determine, using formulas (16), (17), (18), the values ​​of quantities

For t n = +8 0С values t 01, t 02 ,t 03 will accordingly be:

Calculations of network water temperatures are carried out similarly for other values. t n. Using the calculated data and taking the minimum temperature of the network water in the supply pipeline = 70 0 C, we will construct a heating and household temperature graph (see Fig. 4). The break point of the temperature graph will correspond to the network water temperatures = 70 0 C, = 44.9 0 C, = 55.3 0 C, outdoor air temperature = -2.5 0 C. We reduce the obtained values ​​of the network water temperatures for the heating and domestic schedule in Table 4. Next, we proceed to the calculation of the increased temperature schedule. Having specified the value of underheating D t n = 7 0 C we determine the temperature of the heated tap water after the first stage water heater

Let us determine by formula (19) the balance load of hot water supply

Using formula (20), we determine the total temperature difference of the network water d in both stages of water heaters

Using formula (21), we determine the temperature difference of the network water in the first stage water heater for the range of outdoor air temperatures from t n = +8 0 C to t" n = -2.5 0 C

For the specified range of outdoor air temperatures, we determine the temperature difference of the network water in the second stage of the water heater

Let us determine using formulas (22) and (25) the values ​​of quantities d 2 and d 1 for outdoor temperature range t n from t" n = -2.5 0 C before t 0 = -31 0 C. So, for t n = -10 0 C these values ​​will be:

Let us similarly perform calculations of the quantities d 2 and d 1 for values t n = -23 0 C and t n = –31 0 C. The temperatures of the network water in both the supply and return pipelines for an increased temperature curve will be determined using formulas (24) and (26).

Yes, for t n = +8 0 C and t n = -2.5 0 C these values ​​will be

For t n = -10 0 C

Let us similarly perform calculations for the values t n = -23 0 C and -31 0 C. Obtained values d 2, d 1, , we summarize in table 4.

To plot the temperature of the network water in the return pipeline after the air heaters of ventilation systems in the range of outside air temperatures t n = +8 ¸ -2.5 0 C we use formula (32)

Let's determine the value t 2v for t n = +8 0 C. Let us first set the value 0 C. Let us determine the temperature pressure in the heater and, accordingly, for t n = +8 0 C and t n = -2.5 0 C

Let's calculate the left and right sides of the equation

Left side

Right part

Since the numerical values ​​of the right and left sides of the equation are close in value (within 3%), we will accept the value as final.

For ventilation systems with air recirculation, we determine, using formula (34), the temperature of the network water after the air heaters t 2v for t n = t nro = -31 0 C.

Here the values ​​of D t ; t ; t correspond t n = t v = -23 0 C. Since this expression is solved by the selection method, we first set the value t 2v = 51 0 C. Determine the values ​​of D t k and D t

Since the left side of the expression is close in value to the right (0.99"1), the previously accepted value t 2v = 51 0 C will be considered final. Using the data in Table 4, we will construct heating and household and elevated temperature control schedules (see Fig. 4).

Table 4 - Calculation of temperature control schedules for a closed heat supply system.

t N	t 10	t 20	t 30	d 1	d 2	t 1P	t 2P	t 2V
+8	70	44,9	55,3	5,9	8,5	75,9	36,4	17
-2,5	70	44,9	55,3	5,9	8,5	75,9	36,4	44,9
-10	90,2	5205	64,3	4,2	10,2	94,4	42,3	52,5
-23	113,7	63,5	84,4	1,8	12,5	115,6	51	63,5
-31	130	70	95	0,4	14	130,4	56	51

Fig.4. Temperature control charts for a closed heating system (¾ heating and domestic; --- increased)

Construct an adjusted (increased) central quality regulation schedule for an open heat supply system. Accept the balance coefficient a b = 1.1. Accept the minimum temperature of the network water in the supply pipeline for the break point of the temperature graph of 0 C. Take the remaining initial data from the previous part.

Solution. First, we construct temperature graphs , , , using calculations using formulas (13); (14); (15). Next, we will construct a heating and household graph, the break point of which corresponds to the temperature values ​​of the network water 0 C; 0 C; 0 C, and the outside air temperature is 0 C. Next, we proceed to calculate the adjusted schedule. Let's determine the balance load of hot water supply

Let us determine the ratio of the balance load for hot water supply to the design load for heating

For a range of outdoor temperatures t n = +8 0 C; -10 0 C; -25 0 C; -31 0 C, we determine the relative heat consumption for heating using formula (29)`; For example for t n = -10 will be:

Then, taking the values ​​​​known from the previous part t c ; t h ; q; Dt we determine, using formula (30), for each value t n relative costs of network water for heating.

For example, for t n = -10 0 C will be:

Let us perform calculations similarly for other values. t n.

Supply water temperature t 1p and reverse t 2p pipelines for the adjusted schedule will be determined using formulas (27) and (28).

Yes, for t n = -10 0 C we get

Let's do the calculations t 1p and t 2p and for other values t n. Let us determine using the calculated dependencies (32) and (34) the temperature of the network water t 2v after heaters of ventilation systems for t n = +8 0 C and t n = -31 0 C (in the presence of recirculation). When value t n = +8 0 C let’s first set the value t 2v = 23 0 C.

Let's define the values Dt to and Dt To

;

Since the numerical values ​​of the left and right sides of the equation are close, the previously accepted value t 2v = 23 0 C, we will consider it final. Let us also define the values t 2v at t n = t 0 = -31 0 C. Let us first set the value t 2v = 47 0 C

Let's calculate the values ​​of D t to and

We summarize the obtained values ​​of the calculated values ​​in Table 3.5

Table 5 - Calculation of the increased (adjusted) schedule for an open heat supply system.

t n	t 10	t 20	t 30	`Q 0	`G 0	t 1p	t 2p	t 2v
+8	60	40,4	48,6	0,2	0,65	64	39,3	23
1,9	60	40,4	48,6	0,33	0,8	64	39,3	40,4
-10	90.2	52.5	64.3	0,59	0,95	87.8	51.8	52.5
-23	113.7	63.5	84.4	0,84	1,02	113	63,6	63.5
-31	130	70	95	1	1,04	130	70	51

Using the data from Table 5, we will construct heating and domestic, as well as increased temperature schedules for network water.

Fig.5 Heating - household ( ) and increased (----) schedules of network water temperatures for an open heating system

Hydraulic calculation of main heat pipelines of a two-pipe water heating network of a closed heat supply system.

The design diagram of the heating network from the heat source (IT) to the city blocks (CB) is shown in Fig. 6. To compensate for temperature deformations, provide gland compensators. Take the specific pressure loss along the main line in the amount of 30-80 Pa/m.

Fig.6. Design diagram of the main heating network.

Solution. The calculation will be performed for the supply pipeline. Let us take the longest and busiest branch of the heating network from IT to KV 4 (sections 1,2,3) as the main line and proceed to its calculation. According to the hydraulic calculation tables given in the literature, as well as in Appendix No. 12 of the textbook, based on known coolant flow rates, focusing on specific pressure losses R in the range from 30 to 80 Pa/m, we will determine the pipeline diameters for sections 1, 2, 3 d n xS, mm, actual specific pressure loss R, Pa/m, water speed V, m/s.

Based on the known diameters in sections of the main highway, we determine the sum of the local resistance coefficients S x and their equivalent lengths L e. Thus, in section 1 there is a head valve ( x= 0.5), tee for passage when dividing the flow ( x= 1.0), Number of stuffing box compensators ( x= 0.3) on a section will be determined depending on the length of the section L and the maximum permissible distance between fixed supports l. According to Appendix No. 17 of the training manual for D y = 600 mm this distance is 160 meters. Therefore, in section 1 with a length of 400 m, three stuffing box expansion joints should be provided. Sum of local resistance coefficients S x in this area will be

S x= 0.5+1.0 + 3 × 0.3 = 2.4

According to Appendix No. 14 of the textbook (if TO e = 0.0005m) equivalent length l uh for x= 1.0 equals 32.9 m. Equivalent section length L uh will be

L e = l e × S x= 32.9 ×2.4 = 79 m

L n = L+ L e = 400 + 79 = 479 m

Then we determine the pressure loss DP in section 1

D P= R×L n = 42 × 479 = 20118 Pa

Similarly, we will perform a hydraulic calculation of sections 2 and 3 of the main highway (see Table 6 and Table 7).

Next, we proceed to the calculation of branches. Based on the principle of linking pressure loss D P from the flow division point to the end points (EP) for different branches of the system must be equal to each other. Therefore, when hydraulically calculating branches, it is necessary to strive to fulfill the following conditions:

D P 4+5 = D P 2+3 ; D P 6 = D P 5 ; D P 7 = D P 3

Based on these conditions, we will find the approximate specific pressure losses for the branches. So, for a branch with sections 4 and 5 we get

Coefficient a, taking into account the share of pressure losses due to local resistance, will be determined by the formula

Then Pa/m

Focusing on R= 69 Pa/m we will determine pipeline diameters and specific pressure losses using hydraulic calculation tables R, speed V, pressure loss D R in sections 4 and 5. Similarly, we will carry out the calculation of branches 6 and 7, having previously determined the approximate values ​​for them R.

Pa/m

Pa/m

Table 6 - Calculation of equivalent lengths of local resistances

Plot number	dн x S, mm	L, m	Type of local resistance	x	Qty	åx	l e, m	Lе,m
1	630x10	400	1. valve 2. stuffing box compensator	0.5 0.3 1.0	1 3 1	2,4	32,9	79
2	480x10	750	1. sudden contraction 2. stuffing box compensator 3. tee for passage when dividing the flow	0.5 0.3 1.0	1 6 1	3,3	23,4	77
3	426x10	600	1. sudden contraction 2. stuffing box compensator 3. valve	0.5 0.3 0.5	1 4 1	2,2	20,2	44,4
4	426x10	500	1. branch tee 2. valve 3. stuffing box compensator 4. tee for passage	1.5 0.5 0.3 1.0	1 1 4 1	4.2	20.2	85
5	325x8	400	1. stuffing box compensator 2. valve	0.3 0.5	4 1	1.7	14	24
6	325x8	300	1. branch tee 2. stuffing box compensator 3. valve	1.5 0.5 0.5	1 2 2	3.5	14	49
7	325x8	200	1. branch tee when dividing the flow 2.valve 3. stuffing box compensator	1.5 0.5 0.3	1 2 2	3.1	14	44

Table 7 - Hydraulic calculation of main pipelines

Plot number	G, t/h	Length, m	dнхs, mm	V, m/s	R, Pa/m	DP, Pa	åDP, Pa
L	Le	Lп
1 2 3	1700 950 500	400 750 600	79 77 44	479 827 644	630x10 480x10 426x10	1.65 1.6 1.35	42 55 45	20118 45485 28980	94583 74465 28980
4 5	750 350	500 400	85 24	585 424	426x10 325x8	1.68 1.35	70 64	40950 27136	68086 27136
6	400	300	49	349	325x8	1.55	83	28967	28967
7	450	200	44	244	325x8	1.75	105	25620	25620

Let us determine the discrepancy of pressure losses on the branches. The discrepancy on the branch with sections 4 and 5 will be:

The discrepancy on branch 6 will be:

The discrepancy on branch 7 will be.

The standard water temperature in the heating system depends on the air temperature. Therefore, the temperature schedule for supplying coolant to the heating system is calculated in accordance with weather conditions. In this article we will talk about the SNiP requirements for the operation of a heating system for objects for various purposes.

from the article you will learn:

In order to economically and rationally use energy resources in the heating system, the heat supply is tied to the air temperature. The relationship between the temperature of the water in the pipes and the air outside the window is displayed in the form of a graph. The main task of such calculations is to maintain comfortable conditions for residents in apartments. To do this, the air temperature should be about +20…+22ºС.

Coolant temperature in the heating system

The stronger the frost, the faster living spaces heated from the inside lose heat. To compensate for the increased heat loss, the temperature of the water in the heating system increases.

The standard temperature indicator is used in the calculations. It is calculated using a special method and entered into the management documentation. This indicator is based on the average temperature of the 5 coldest days of the year. For the calculation, the 8 coldest winters over a 50-year period are taken.

Why does drawing up a temperature schedule for the supply of coolant to the heating system happen this way? The main thing here is to be prepared for the most severe frosts, which happen every few years. Climatic conditions in a particular region can change over several decades. This will be taken into account when recalculating the schedule.

The value of the average daily temperature is also important for calculating the safety margin of heating systems. By understanding the maximum load, you can accurately calculate the characteristics of the required pipelines, shut-off valves and other elements. This saves on creating communications. Considering the scale of construction for urban heating systems, the amount of savings will be quite large.

The temperature in the apartment directly depends on how hot the coolant in the pipes is. In addition, other factors are also important here:

• air temperature outside the window;
• wind speed. With strong wind loads, heat loss through doorways and windows increases;
• the quality of sealing joints on the walls, as well as the general condition of the finishing and insulation of the facade.

Building codes change as technology advances. This is reflected, among other things, in the indicators in the graph of coolant temperature depending on the outside temperature. If rooms retain heat better, then less energy resources can be spent.

Developers in modern conditions are more careful about the thermal insulation of facades, foundations, basements and roofs. This increases the cost of objects. However, at the same time as construction costs increase, heating and hot water costs decrease. Overpayment at the construction stage pays off over time and provides good savings.

The heating of rooms is directly affected not even by how hot the water in the pipes is. The main thing here is the temperature of the heating radiators. It is usually within +70…+90ºС.

Several factors influence battery heating.

1. Air temperature.

2. Features of the heating system. The indicator indicated in the temperature schedule for the coolant supply to the heating system depends on its type. In single-pipe systems, heating water to +105ºС is considered normal. Due to better circulation, two-pipe heating provides higher heat transfer. This allows you to reduce the temperature to +95ºС. Moreover, if at the inlet the water needs to be heated, respectively, to +105ºС and +95ºС, then at the outlet its temperature in both cases should be at the level of +70ºС.

To prevent the coolant from boiling when heated above +100ºС, it is supplied to the pipelines under pressure. Theoretically, it can be quite high. This should provide a large supply of heat. However, in practice, not all networks allow water to be supplied under high pressure due to their wear and tear. As a result, the temperature decreases, and during severe frosts there may be a lack of heat in apartments and other heated rooms.

Observe the 4 main requirements for the quality of heat supply in apartment buildings. They are established by Appendix 1 to Rules No. 354. Help system experts have prepared a summary table with permissible deviations when supplying heat to MKD.

3. Direction of water supply to radiators. With the upper wiring, the difference is 2ºС, with the lower wiring - 3ºС.

4. Type of heating devices used. Radiators and convectors differ in the amount of heat they give off, which means they must operate in different temperature conditions. Radiators have better heat transfer performance.

At the same time, the amount of heat released is influenced, among other things, by the temperature of the street air. It is this that is the determining factor in the temperature schedule of coolant supply to the heating system.

When the water temperature is indicated as +95ºС, we are talking about the coolant at the entrance to the living space. Considering the heat loss during transportation, the boiler room must heat it much more.

To supply water at the required temperature to the heating pipes in apartments, special equipment is installed in the basement. It mixes hot water from the boiler room with that coming from the return.

Temperature graph of coolant supply to the heating system

The graph shows what the water temperature should be at the entrance to the living space and at the exit from it, depending on the street temperature.

The table presented will help you easily determine the degree of heating of the coolant in the central heating system.

Outside air temperature, °C	Inlet water temperature, °C			Temperature indicators of water in the heating system, °C		Temperature indicators of water after the heating system, °C

Representatives of utility services and resource supply organizations measure water temperature using a thermometer. Columns 5 and 6 indicate the numbers for the pipeline through which the hot coolant is supplied. Column 7 – for return.

The first three columns indicate increased temperature - these are indicators for heat generating organizations. These figures are given without taking into account heat losses occurring during the transportation of the coolant.

The temperature schedule for the supply of coolant to the heating system is needed not only by resource supply organizations. If the actual temperature differs from the standard temperature, consumers have grounds to recalculate the cost of the service. In their complaints they indicate how warm the air in the apartments is. This is the easiest parameter to measure. Inspecting authorities can already track the temperature of the coolant, and if it does not comply with the schedule, force the resource supplying organization to fulfill its duties.

Is it possible to charge a fee for heating basements and loggias, whether to recalculate for a bathroom and how to calculate the fee when the radiator is dismantled - read the answers to these and other questions in the expert article.

A reason for complaints appears if the air in the apartment cools below the following values:

• in corner rooms during the daytime – below +20ºС;
• in the central rooms during the daytime – below +18ºС;
• in corner rooms at night – below +17ºС;
• in the central rooms at night – below +15ºС.

SNiP

Requirements for the operation of heating systems are set out in SNiP 41-01-2003. Much attention is paid to security issues in this document. In the case of heating, a heated coolant poses a potential danger, which is why its temperature for residential and public buildings is limited. As a rule, it does not exceed +95ºС.

If the water in the internal pipelines of the heating system heats up above +100ºС, then the following safety measures are provided at such facilities:

• Heating pipes are laid in special shafts. In the event of a breakthrough, the coolant will remain in these reinforced channels and will not be a source of danger to people;
• pipelines in high-rise buildings have special structural elements or devices that prevent water from boiling.

If the building has heating made of polymer pipes, then the temperature of the coolant should not exceed +90ºС.

We have already mentioned above that in addition to the temperature schedule for the supply of coolant to the heating system, responsible organizations need to monitor how hot the available heating elements are. These rules are also given in SNiP. Permissible temperatures vary depending on the purpose of the room.

First of all, everything here is determined by the same safety rules. For example, in children's and medical institutions, permissible temperatures are minimal. In public places and at various production facilities, there are usually no special restrictions placed on them.

According to general rules, the surface of heating radiators should not heat up above +90ºС. If this figure is exceeded, negative consequences begin. They consist, first of all, in the burning of paint on the batteries, as well as in the combustion of dust in the air. This fills the indoor atmosphere with substances that are harmful to health. In addition, harm to the appearance of heating devices is possible.

Another issue is ensuring safety in rooms with hot radiators. According to the general rules, it is necessary to protect heating devices whose surface temperature is above +75ºС. Typically, lattice fencing is used for this. They do not interfere with air circulation. At the same time, SNiP requires mandatory protection of radiators in children's institutions.

In accordance with SNiP, the maximum temperature of the coolant varies depending on the purpose of the room. It is determined both by the heating characteristics of different buildings and by safety considerations. For example, in medical institutions the permissible water temperature in the pipes is the lowest. It is +85ºС.

The maximum heated coolant (up to +150ºС) can be supplied to the following objects:

• lobbies;
• heated pedestrian crossings;
• landings;
• technical premises;
• industrial buildings that do not contain aerosols and dust prone to fire.

The temperature schedule for the supply of coolant to the heating system according to SNiP is used only in the cold season. In the warm season, the document in question normalizes microclimate parameters only from the point of view of ventilation and air conditioning.

Each heating system has certain characteristics. These include power, heat transfer and operating temperature. They determine the efficiency of work, directly affecting the comfort of living in the house. How to choose the right temperature schedule and heating mode, and its calculation?

Drawing up a temperature chart

The temperature schedule of the heating system is calculated using several parameters. Not only the degree of heating of the premises, but also the coolant consumption depends on the selected mode. This also affects the current costs of heating maintenance.

The compiled heating temperature schedule depends on several parameters. The main one is the level of water heating in the mains. It, in turn, consists of the following characteristics:

• Temperature in the supply and return pipes. Measurements are taken in the corresponding boiler nozzles;
• Characteristics of the degree of air heating indoors and outdoors.

Correct calculation of the heating temperature schedule begins with calculating the difference between the temperature of hot water in the direct and supply pipes. This value has the following designation:

∆T=Tin-Tob

Where Tin– water temperature in the supply line, Tob– degree of water heating in the return pipe.

To increase the heat transfer of the heating system, it is necessary to increase the first value. To reduce coolant flow, ∆t should be minimal. This is precisely the main difficulty, since the temperature schedule of the heating boiler directly depends on external factors - heat losses in the building, air outside.

To optimize heating power, it is necessary to insulate the external walls of the house. This will reduce heat losses and energy consumption.

Temperature calculation

To determine the optimal temperature regime, it is necessary to take into account the characteristics of heating components - radiators and batteries. In particular, specific power (W/cm²). This will directly affect the thermal transfer of heated water to the air in the room.

It is also necessary to make a number of preliminary calculations. This takes into account the characteristics of the house and heating devices:

• Heat transfer resistance coefficient of external walls and window structures. It must be at least 3.35 m²*C/W. Depends on the climatic characteristics of the region;
• Surface power of radiators.

The temperature graph of the heating system is directly dependent on these parameters. To calculate the heat loss of a house, you need to know the thickness of the external walls and the material of the building. The surface power of batteries is calculated using the following formula:

Ore=P/Fact

Where R– maximum power, W, fact– radiator area, cm².

According to the data obtained, a temperature regime for heating and a heat transfer graph are drawn up depending on the outside temperature.

To change heating parameters in a timely manner, install a heating temperature regulator. This device connects to outdoor and indoor thermometers. Depending on the current indicators, the operation of the boiler or the volume of coolant flow into the radiators is adjusted.

The weekly programmer is the optimal heating temperature regulator. With its help, you can automate the operation of the entire system as much as possible.

Central heating

For district heating, the temperature regime of the heating system depends on the characteristics of the system. Currently, there are several types of coolant parameters supplied to consumers:

• 150°C/70°C. To normalize the water temperature, the elevator unit mixes it with the cooled flow. In this case, you can create an individual temperature schedule for the heating boiler room for a specific house;
• 90°С/70°С. Typical for small private heating systems designed to supply heat to several apartment buildings. In this case, you do not need to install the mixing unit.

The responsibility of utility services is to calculate the temperature heating schedule and control its parameters. In this case, the degree of air heating in residential premises should be at +22°C. For non-residential residents this figure is slightly lower – +16°C.

For a centralized system, drawing up a correct temperature schedule for the heating boiler room is required to ensure optimal comfortable temperature in apartments. The main problem is the lack of feedback - it is impossible to adjust the coolant parameters depending on the degree of air heating in each apartment. That is why a temperature graph of the heating system is drawn up.

A copy of the heating schedule can be requested from the Management Company. With its help you can control the quality of the services provided.

Heating system

It is often not necessary to make similar calculations for autonomous heating systems in a private home. If the circuit includes indoor and outdoor temperature sensors, information about them will be sent to the boiler control unit.

Therefore, to reduce energy consumption, low-temperature heating modes are most often chosen. It is characterized by relatively low heating of water (up to +70°C) and a high degree of circulation. This is necessary for uniform heat distribution across all heating devices.

To implement such a temperature regime for the heating system, the following conditions will need to be met:

• Minimum heat losses in the house. However, one should not forget about normal air exchange - ventilation is mandatory;
• High thermal output of radiators;
• Installation of automatic temperature controllers in heating.

If there is a need to perform a correct calculation of the system’s operation, it is recommended to use special software systems. There are too many factors to take into account to calculate on your own. But with their help you can create approximate temperature graphs of heating modes.

However, it should be borne in mind that an accurate calculation of the heat supply temperature schedule is done for each system individually. The tables show the recommended values ​​for the degree of heating of the coolant in the supply and return pipes depending on the outside temperature. When performing calculations, the characteristics of the building and the climatic features of the region were not taken into account. But even so, they can be used as a basis for creating a temperature chart for the heating system.

The maximum load of the system should not affect the quality of boiler operation. Therefore, it is recommended to purchase it with a power reserve of 15-20%.

Even the most accurate temperature schedule of a heating boiler room will exhibit deviations in calculated and actual data during operation. This is due to the operating features of the system. What factors can influence the current temperature regime of heat supply?

• Contamination of pipelines and radiators. To avoid this, the heating system should be cleaned periodically;
• Incorrect operation of control and shut-off valves. The functionality of all components must be checked;
• Violation of the boiler's operating mode - sudden changes in temperature and, as a consequence, pressure.

Maintaining the optimal temperature regime of the system is only possible with the correct selection of its components. To do this, their operational and technical properties should be taken into account.

The battery heating can be adjusted using a thermostat, the operating principle of which can be found in the video:

There are certain patterns according to which the temperature of the coolant in central heating changes. In order to adequately track these fluctuations, there are special graphs.

Causes of temperature changes

To begin with, it is important to understand a few points:

1. When weather conditions change, this automatically entails a change in heat loss. When cold weather sets in, to maintain an optimal microclimate in the home, an order of magnitude more thermal energy is spent than during the warm period. In this case, the level of heat consumed is not calculated by the exact temperature of the street air: for this, the so-called. "delta" of the difference between the street and the interior. For example, +25 degrees in an apartment and -20 outside its walls will entail exactly the same heat costs as at +18 and -27, respectively.
2. The constancy of the heat flow from the radiators is ensured by the stable temperature of the coolant. As the temperature in the room decreases, there will be a slight rise in the temperature of the radiators: this is facilitated by an increase in the delta between the coolant and the air in the room. In any case, this will not be able to adequately compensate for the increase in heat losses through the walls. This is explained by the setting of restrictions for the lower temperature limit in the home by the current SNiP at +18-22 degrees.

It is most logical to solve the problem of increasing losses by increasing the temperature of the coolant. It is important that its increase occurs parallel to the decrease in air temperature outside the window: the colder it is there, the greater the heat loss that needs to be replenished. To facilitate orientation in this matter, at some stage it was decided to create special tables for reconciling both values. Based on this, we can say that the temperature graph of the heating system means the derivation of the dependence of the level of water heating in the supply and return pipelines in relation to the temperature conditions outside.

Features of the temperature graph

The above graphs come in two varieties:

1. For heat supply networks.
2. For heating system inside the house.

To understand how both of these concepts differ, it is advisable to first understand the features of centralized heating.

Connection between CHP and heating networks

The purpose of this combination is to communicate the proper heating level to the coolant, followed by its transportation to the place of consumption. Heating pipelines are usually several tens of kilometers long, with a total surface area of ​​tens of thousands of square meters. Although the main networks are subject to careful thermal insulation, it is impossible to do without heat loss.

As you move between the thermal power plant (or boiler room) and the living quarters, some cooling of the service water is observed. The conclusion suggests itself: in order to convey to the consumer an acceptable level of heating of the coolant, it must be supplied inside the heating main from the thermal power plant in the maximum heated state. The rise in temperature is limited by the boiling point. It can be shifted towards higher temperatures if the pressure in the pipes is increased.

The standard pressure indicator in the supply pipe of the heating main is within 7-8 atm. This level, despite the pressure loss during coolant transportation, makes it possible to ensure efficient operation of the heating system in buildings up to 16 floors high. In this case, additional pumps are usually not needed.

It is very important that such pressure does not create a danger for the system as a whole: routes, risers, connections, mixing hoses and other components remain operational for a long time. Taking into account a certain margin for the upper limit of the supply temperature, its value is taken as +150 degrees. The most standard temperature curves for supplying coolant to the heating system range between 150/70 - 105/70 (supply and return temperatures).

Features of coolant supply to the heating system

The home heating system is characterized by a number of additional restrictions:

• The maximum heating value of the coolant in the circuit is limited to +95 degrees for a two-pipe system and +105 for a one-pipe heating system. It should be noted that preschool educational institutions are characterized by the presence of more stringent restrictions: there the temperature of the batteries should not rise above +37 degrees. To compensate for this decrease in supply temperature, it is necessary to increase the number of radiator sections. The interiors of kindergartens located in regions with particularly harsh climatic conditions are literally crammed with batteries.
• It is advisable to achieve a minimum temperature delta of the heating supply schedule between the supply and return pipelines: otherwise, the degree of heating of the radiator sections in the building will have a big difference. To do this, the coolant inside the system must move as quickly as possible. However, there is a danger here: due to the high speed of water circulation inside the heating circuit, its temperature at the exit back into the route will be excessively high. As a result, this can lead to serious disruptions in the operation of the thermal power plant.

Influence of climatic zones on outside air temperature

The main factor that directly influences the preparation of the temperature schedule for the heating season is the calculated winter temperature. As the compilation proceeds, they try to ensure that the highest values ​​(95/70 and 105/70) at maximum frosts guarantee the required SNiP temperature. The outside air temperature for heating calculations is taken from a special table of climatic zones.

Adjustment features

The parameters of heating routes are the responsibility of the management of thermal power plants and heating networks. At the same time, housing office employees are responsible for the network parameters inside the building. Mostly, residents' complaints about the cold concern deviations to the lower side. Much less common are situations where measurements inside thermal units indicate an increased return temperature.

There are several ways to normalize system parameters that you can implement yourself:

• Reaming the nozzle. The problem of lowering the temperature of the liquid in the return can be solved by expanding the elevator nozzle. To do this, you need to close all the gates and valves on the elevator. After this, the module is removed, its nozzle is pulled out and drilled out 0.5-1 mm. After assembling the elevator, it is started to bleed air in the reverse order. It is recommended to replace the paronite seals on the flanges with rubber ones: they are made to the size of the flange from a car inner tube.
• Choke suppression. In extreme cases (during the onset of extremely low frosts), the nozzle can be completely removed. In this case, there is a danger that the suction will begin to act as a jumper: to prevent this, it is turned off. For this, a steel pancake with a thickness of 1 mm is used. This method is emergency, because this can cause a jump in battery temperature to +130 degrees.
• Differential control. A temporary way to solve the problem of rising temperature is to adjust the differential using an elevator valve. To do this, it is necessary to redirect the hot water supply to the supply pipe: the return pipe is equipped with a pressure gauge. The inlet valve of the return pipeline is completely closed. Next, you need to open the valve little by little, constantly checking your actions with the readings of the pressure gauge.

A simply closed valve can cause the circuit to stop and defrost. A reduction in the difference is achieved due to an increase in return pressure (0.2 atm/day). The temperature in the system must be checked every day: it must correspond to the heating temperature schedule.