Economic consumption of energy resources in heating system, can be achieved if certain requirements are met. One of the options is the presence of a temperature chart, which reflects the ratio of the temperature emanating from the heating source to external environment. The value of the values ​​makes it possible to optimally distribute heat and hot water to the consumer.

High-rise buildings are connected mainly to central heating. Sources that convey thermal energy, are boiler houses or CHP. Water is used as a heat carrier. It is heated to a predetermined temperature.

Having passed full cycle through the system, the coolant, already cooled, returns to the source and reheating occurs. Sources are connected to the consumer by thermal networks. As the environment changes temperature regime, thermal energy should be regulated so that the consumer receives the required volume.

Heat regulation from central system can be produced in two ways:

1. Quantitative. In this form, the flow rate of water changes, but the temperature is constant.
2. Qualitative. The temperature of the liquid changes, but its flow rate does not change.

In our systems, the second variant of regulation is used, that is, qualitative. Z Here there is a direct relationship between two temperatures: coolant and environment. And the calculation is carried out in such a way as to provide heat in the room of 18 degrees and above.

Hence, we can say that the temperature curve of the source is a broken curve. The change in its directions depends on the temperature difference (coolant and outside air).

Dependency graph may vary.

A particular chart has a dependency on:

1. Technical and economic indicators.
2. Equipment for a CHP or boiler room.
3. climate.

High performance of the coolant provides the consumer with a large thermal energy.

An example of a circuit is shown below, where T1 is the temperature of the coolant, Tnv is the outdoor air:

It is also used, the diagram of the returned coolant. A boiler house or CHP according to such a scheme can evaluate the efficiency of the source. It is considered high when the returned liquid arrives cooled.

The stability of the scheme depends on the design values ​​of the liquid flow of high-rise buildings. If the flow rate through the heating circuit increases, the water will return uncooled, as the flow rate will increase. Conversely, at the lowest cost, return water will be cool enough.

The supplier's interest is, of course, in the flow of return water in a chilled state. But there are certain limits to reduce the flow, since a decrease leads to losses in the amount of heat. The consumer will begin to lower the internal degree in the apartment, which will lead to a violation of building codes and discomfort to the inhabitants.

What does it depend on?

The temperature curve depends on two quantities: outside air and coolant. Frosty weather leads to an increase in the degree of coolant. When designing a central source, the size of the equipment, the building and the section of pipes are taken into account.

The value of the temperature leaving the boiler room is 90 degrees, so that at minus 23°C, it would be warm in the apartments and have a value of 22°C. Then the return water returns to 70 degrees. These standards are in line with the normal comfortable living in the House.

Analysis and adjustment of operating modes is carried out using a temperature scheme. For example, the return of a liquid with an elevated temperature will indicate high coolant costs. Underestimated data will be considered as a consumption deficit.

Previously, for 10-storey buildings, a scheme with calculated data of 95-70°C was introduced. The buildings above had their chart 105-70°C. Modern new buildings may have a different scheme, at the discretion of the designer. More often, there are diagrams of 90-70°C, and maybe 80-60°C.

Temperature chart 95-70:

temperature graph 95-70

How is it calculated?

The control method is selected, then the calculation is made. The calculation-winter and reverse order of water inflow, the amount of outside air, the order at the break point of the diagram are taken into account. There are two diagrams, where one of them considers only heating, the other one considers heating with hot water consumption.

For an example calculation, we will use methodological development Roskommunenergo.

The initial data for the heat generating station will be:

1. Tnv- the amount of outside air.
2. TVN- indoor air.
3. T1- coolant from the source.
4. T2- return flow of water.
5. T3- the entrance to the building.

We will consider several options for supplying heat with a value of 150, 130 and 115 degrees.

At the same time, at the exit they will have 70 ° C.

The results obtained are brought into a single table for the subsequent construction of the curve:

So we got three various schemes which can be taken as a basis. It would be more correct to calculate the diagram individually for each system. Here we have considered the recommended values, excluding climatic features region and building characteristics.

To reduce power consumption, it is enough to choose a low-temperature order of 70 degrees and will be provided uniform distribution heat in the heating circuit. The boiler should be taken with a power reserve so that the load of the system does not affect quality work unit.

Adjustment

Heating regulator

Automatic control is provided by the heating controller.

It includes the following details:

1. Computing and matching panel.
2. Executive device at the water supply line.
3. Executive device, which performs the function of mixing liquid from the returned liquid (return).
4. boost pump and a sensor on the water supply line.
5. Three sensors (on the return line, on the street, inside the building). There may be several in a room.

The regulator covers the liquid supply, thereby increasing the value between the return and supply to the value provided by the sensors.

To increase the flow, there is a booster pump, and the corresponding command from the regulator. The incoming flow is regulated by a "cold bypass". That is, the temperature drops. Some of the liquid that circulates along the circuit is sent to the supply.

Information is taken by sensors and transmitted to control units, as a result of which, there is a redistribution of flows that provide rigid temperature chart heating systems.

Sometimes, a computing device is used, where the DHW and heating regulators are combined.

The hot water regulator has more a simple circuit management. The hot water sensor regulates the flow of water with a stable value of 50°C.

Regulator benefits:

1. The temperature regime is strictly maintained.
2. Exclusion of liquid overheating.
3. Fuel Economy and energy.
4. The consumer, regardless of distance, receives heat equally.

Table with temperature chart

The operating mode of the boilers depends on the weather of the environment.

If we take various objects, for example, factory premises, multi-storey and private house, all will have an individual heat chart.

In the table, we show the temperature diagram of the dependence of residential buildings on the outside air:

Outside temperature	Temperature network water in the supply pipeline	Temperature of network water in the return pipeline
+10	70	55
+9	70	54
+8	70	53
+7	70	52
+6	70	51
+5	70	50
+4	70	49
+3	70	48
+2	70	47
+1	70	46
0	70	45
-1	72	46
-2	74	47
-3	76	48
-4	79	49
-5	81	50
-6	84	51
-7	86	52
-8	89	53
-9	91	54
-10	93	55
-11	96	56
-12	98	57
-13	100	58
-14	103	59
-15	105	60
-16	107	61
-17	110	62
-18	112	63
-19	114	64
-20	116	65
-21	119	66
-22	121	66
-23	123	67
-24	126	68
-25	128	69
-26	130	70

SNiP

There are certain rules that must be observed in the creation of projects on heating network and transporting hot water to the consumer, where the supply of water vapor must be carried out at 400°C, at a pressure of 6.3 bar. The supply of heat from the source is recommended to be released to the consumer with values ​​of 90/70 °C or 115/70 °C.

Regulatory requirements should be followed for compliance with the approved documentation with the obligatory coordination with the Ministry of Construction of the country.

Let's start with a simple diagram:

In the diagram we see a boiler, two pipes, expansion tank and a group of heating radiators. Red pipe through which hot water is coming from the boiler to the radiators is called DIRECT. And the lower (blue) pipe through which more cold water comes back, so it's called - REVERSE. Knowing that when heated, all bodies expand (including water), an expansion tank is installed in our system. It performs two functions at once: it is a supply of water to feed the system and excess water goes into it when it expands from heating. Water in this system is a heat carrier and therefore must circulate from the boiler to the radiators and vice versa. Either a pump or, under certain conditions, the force of the earth's gravity can make it circulate. If everything is clear with the pump, then with gravity, many may have difficulties and questions. We dedicated a separate topic to them. For a deeper understanding of the process, let's turn to the numbers. For example, the heat loss of a house is 10 kW. The operating mode of the heating system is stable, that is, the system neither warms up nor cools down. In the house, the temperature does not rise or fall. This means that the boiler generates 10 kW and the radiators dissipate 10 kW. From a school physics course, we know that we need 4.19 kJ of heat to heat 1 kg of water by 1 degree. If we heat 1 kg of water by 1 degree every second, then we need power

Q \u003d 4.19 * 1 (kg) * 1 (deg) / 1 (sec) \u003d 4.19 kW.

If our boiler has a power of 10 kW, then it can heat 10 / 4.2 = 2.4 kilograms of water per second by 1 degree, or 1 kilogram of water by 2.4 degrees, or 100 grams of water (not vodka) by 24 degrees. The formula for boiler power looks like this:

Qcat \u003d 4.19 * G * (Tout-Tin) (kW),

where
G- water flow through the boiler kg / s
Tout - water temperature at the outlet of the boiler (possibly T direct)
Тin - water temperature at the inlet to the boiler (possible T return)
Radiators dissipate heat and the amount of heat they give off depends on the heat transfer coefficient, the surface area of ​​the radiator and the temperature difference between the radiator wall and the air in the room. The formula looks like this:

Qrad \u003d k * F * (Trad-Tvozd),

where
k is the heat transfer coefficient. The value for household radiators is practically constant and equal to k \u003d 10 watt / (kv meter * deg).
F- total area of ​​radiators (in sq. meters)
Trad- average temperature radiator walls
Tair is the air temperature in the room.
With a stable mode of operation of our system, the equality will always be satisfied

Qcat=Qrad

Let us consider in more detail the operation of radiators using calculations and numbers.
Let's say the total area of ​​their ribs is 20 square meters (which approximately corresponds to 100 ribs). Our 10 kW = 10000 W, these radiators will give out with a temperature difference of

dT=10000/(10*20)=50 degrees

If the temperature in the room is 20 degrees, then the average surface temperature of the radiator will be

20+50=70 degrees.

When our radiators have large area, for example 25 square meters(about 125 ribs) then

dT=10000/(10*25)=40 degrees.

And the average surface temperature is

20+40=60 degrees.

Hence the conclusion: If you want to make a low-temperature heating system, do not skimp on radiators. The average temperature is the arithmetic mean between the temperatures at the inlet and outlet of the radiators.

Тav=(Тstraight+Тоbr)/2;

The temperature difference between the direct and return is also an important value and characterizes the circulation of water through the radiators.

dT=Tstraight-Tobr;

Remember that

Q \u003d 4.19 * G * (Tpr-Tobr) \u003d 4.19 * G * dT

At a constant power, an increase in water flow through the device will lead to a decrease in dT, and vice versa, with a decrease in flow, dT will increase. If we ask that dT in our system is 10 degrees, then in the first case, when Tav=70 degrees, after simple calculations we get Tpr=75 deg and Tobr=65 deg. The water flow through the boiler is

G=Q/(4.19*dT)=10/(4.19*10)=0.24 kg/sec.

If we reduce the water flow exactly by half, and leave the boiler power the same, then the temperature difference dT will double. IN previous example we set dT at 10 degrees, now when the flow decreases, it will become dT=20 degrees. With the same Tav=70, we get Tpr-80 deg and Tobr=60 deg. As we can see, a decrease in water consumption entails an increase in the direct temperature and a decrease in the return temperature. In cases where the flow rate drops to some critical value, we can observe the boiling of water in the system. (boiling temperature = 100 degrees) Also, boiling of water can occur with an excess of boiler power. This phenomenon is extremely undesirable and very dangerous, therefore a well-designed and thought-out system, competent selection of equipment and high-quality installation exclude this phenomenon.
As we can see from the example, the temperature regime of the heating system depends on the power that needs to be transferred to the room, the area of ​​\u200b\u200bthe radiators and the flow rate of the coolant. The volume of coolant poured into the system with a stable mode of operation does not play any role. The only thing that affects the volume is the dynamics of the system, that is, the time of heating and cooling. The larger it is, the longer the warm-up time and the longer time cooling, which is undoubtedly a plus in some cases. It remains to consider the operation of the system in these modes.
Let's go back to our example with a 10 kW boiler and 100 fin radiators with 20 squares of area. The pump sets the flow rate at G=0.24 kg/sec. We set the capacity of the system to 240 liters.
For example, the owners came to the house after a long absence and began to heat. During their absence, the house cooled down to 5 degrees, as did the water in the heating system. By turning on the pump, we will create water circulation in the system, but until the boiler is ignited, the temperature of the direct and return will be the same and equal to 5 degrees. After the boiler is ignited and reaches a power of 10 kW, the picture will be as follows: The water temperature at the inlet to the boiler will be 5 degrees, at the outlet of the boiler 15 degrees, the temperature at the inlet to the radiators is 15 degrees, and at the outlet of them a little less than 15. ( At such temperatures, radiators practically do not emit anything) All this will continue for 1000 seconds until the pump pumps all the water through the system and a return line with a temperature of almost 15 degrees comes to the boiler. After that, the boiler will already give out 25 degrees, and the radiators will return water to the boiler with a temperature slightly less than 25 (about 23-24 degrees). And so again 1000 seconds.
In the end, the system will warm up to 75 degrees at the outlet, and the radiators will return 65 degrees and the system will go into stable mode. If there were 120 liters in the system, and not 240, then the system would warm up 2 times faster. In the case when the boiler is extinguished and the system is hot, the cooling process will begin. That is, the system will give the house the accumulated heat. It is clear that the larger the volume of the coolant, the longer this process will take. When operating solid fuel boilers, this allows you to stretch the time between reloads. Most often, this role is taken over by, to which we devoted a separate topic. Like various types heating systems.

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

The requirements for the temperature of the coolant are set out in normative documents that establish the design, installation and use engineering systems residential and public buildings. They are described in the State building codes and rules:

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

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

For individual heating to decide what should be the temperature of the coolant, should be taking into account such factors:

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

According to SNiP 2.04.05 "Heating, ventilation and air conditioning" (clause 3.20), the coolant limit values ​​are as follows:

Depending on the 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 norms prohibit more heating.

For calculation optimal performance special charts and tables can be used that define the norms depending on the season:

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

Optimal values ​​in an individual heating system

H2_2

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

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

A little more difficult with solid fuel devices, they do not regulate the heating of the liquid, and can easily turn it into steam. And it is impossible to reduce the heat from coal or wood by turning the knob in such a situation. At the same time, the control of heating of the coolant is rather conditional with high errors and is performed by rotary thermostats and mechanical dampers.

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

One-pipe and two-pipe lines

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

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

Matching the temperature of the heat carrier and the boiler

Regulators help to coordinate the temperature of the coolant and the boiler. These are devices that create automatic control and correction of return and supply temperatures.

The return temperature depends on the amount of liquid passing through it. The regulators cover the liquid supply and increase the difference between the return and supply to the level that is needed, and the necessary pointers are installed on the sensor.

If you need to increase the flow, then a boost pump can be added to the network, which is controlled by a regulator. To reduce the heating of the supply, a “cold start” is used: that part of the liquid that has passed through the network is again transferred from the return to the inlet.

The regulator redistributes the supply and return flows according to the data taken by the sensor, and ensures strict temperature norms heating networks.

Ways to reduce heat loss

The above information can be used to correct calculation coolant temperature standards and tell you how to determine the situation when you need to use the regulator.

But it is important to remember that the temperature in the room is affected not only by the temperature of the coolant, outdoor air and wind strength. The degree of insulation of the facade, doors and windows in the house should also be taken into account.

To reduce the heat loss of housing, you need to worry about its maximum thermal insulation. Insulated walls, sealed doors, metal-plastic windows help reduce heat loss. It will also reduce heating costs.

Can the water in the well freeze? No, the water will not freeze, because. both in sandy and artesian well water is below the freezing point of the ground. Is it possible to install a pipe with a diameter greater than 133 mm in a sandy well of a water supply system (I have a pump for a large pipe)? It does not make sense when arranging sand well install a larger diameter pipe, because sand well productivity is low. The Malysh pump is specially designed for such wells. Can rust steel pipe in a water well? Slow enough. Since when arranging a well suburban water supply it is sealed, there is no oxygen access to the well and the oxidation process is very slow. What are the pipe diameters for an individual well? What is the productivity of the well at various diameters pipes? Pipe diameters for arranging a well for water: 114 - 133 (mm) - well productivity 1 - 3 cubic meters / hour; 127 - 159 (mm) - well productivity 1 - 5 cubic meters / hour; 168 ( mm) - well productivity 3 - 10 cubic meters / hour; REMEMBER! It is necessary that n...