Computers have been operating successfully for a long time not only on the desks of office workers, but also in production and production management systems. technological processes. Automation successfully controls the parameters of heating systems of buildings, providing...
The specified required air temperature (sometimes changing throughout the day to save money).
But the automation needs to be properly configured, given the initial data and algorithms to work! This article discusses the optimal heating temperature schedule - the dependence of the coolant temperature of a water heating system at different temperatures outside air.
This topic has already been discussed in the article about. Here we will not calculate the heat loss of an object, but will consider a situation where these heat losses are known from previous calculations or from data from the actual operation of an existing facility. If the facility is operational, then it is better to take the value of heat loss at the design temperature of the outside air from the statistical actual data of previous years of operation.
In the article mentioned above, to construct the dependences of the coolant temperature on the outside air temperature, a system of nonlinear equations is solved numerically. This article will present “direct” formulas for calculating the “supply” and “return” water temperatures, which represent an analytical solution to the problem.
You can read about the colors of Excel sheet cells that are used for formatting in articles on the page « ».
Calculation of heating temperature graph in Excel.
So, when setting up the boiler operation and/or thermal unit Based on the outside air temperature, the automation system needs to set a temperature schedule.
It may be more correct to place the air temperature sensor inside the building and configure the operation of the coolant temperature control system based on the internal air temperature. But it is often difficult to choose where to install the sensor inside due to different temperatures V various rooms object or due to the significant distance of this place from the thermal unit.
Let's look at an example. Let's say we have an object - a building or a group of buildings that receive thermal energy from one common closed heat supply source - a boiler room and/or a heating unit. A closed source is a source from which sampling is prohibited hot water for water supply. In our example, we will assume that in addition to the direct selection of hot water, there is no selection of heat for heating water for hot water supply.
To compare and check the correctness of the calculations, let’s take the initial data from the above-mentioned article “Calculation of water heating in 5 minutes!” and create a small calculation program in Excel temperature chart heating.
Initial data:
1. Estimated (or actual) heat loss of an object (building) Q p in Gcal/hour at the design outdoor temperature t nr write down
to cell D3: 0,004790
2. Estimated air temperature inside the object (building) t vr in °C enter
to cell D4: 20
3. Estimated outside air temperature t nr in °C we enter
to cell D5: -37
4. Estimated water temperature at the “supply” t pr enter in °C
to cell D6: 90
5. Estimated return water temperature t op in °C enter
to cell D7: 70
6. Indicator of nonlinearity of heat transfer of used heating devices n write down
to cell D8: 0,30
7. Current (we are interested in) outside air temperature t n in °C we enter
to cell D9: -10
Cell valuesD3 – D8 for a specific object are written once and are not changed further. Cell valueD8 can (and should) be changed by determining coolant parameters for different weather conditions.
Calculation results:
8. Estimated water flow in the system GR in t/hour we calculate
in cell D11: =D3*1000/(D6-D7) =0,239
GR = QR *1000/(tetc — top )
9. Relative heat flux q define
in cell D12: =(D4-D9)/(D4-D5) =0,53
q =(tvr — tn )/(tvr — tnr )
10. Supply water temperature tP in °C we calculate
in cell D13: =D4+0.5*(D6-D7)*D12+0.5*(D6+D7-2*D4)*D12^(1/(1+D8)) =61,9
tP = tvr +0,5*(tetc – top )* q +0,5*(tetc + top -2* tvr )* q (1/(1+ n ))
11. Return water temperature tO in °C we calculate
in cell D14: =D4-0.5*(D6-D7)*D12+0.5*(D6+D7-2*D4)*D12^(1/(1+D8)) =51,4
tO = tvr -0,5*(tetc – top )* q +0,5*(tetc + top -2* tvr )* q (1/(1+ n ))
Calculation of supply water temperature in Excel tP and on the return line tO for selected outside temperature tn completed.
Let's make a similar calculation for several different outside temperatures and build a heating temperature graph. (You can read about how to build graphs in Excel.)
Let's compare the obtained values of the heating temperature graph with the results obtained in the article “Calculation of water heating in 5 minutes!” - the values are the same!
Results.
The practical value of the presented calculation of the heating temperature schedule is that it takes into account the type installed devices and the direction of movement of the coolant in these devices. Heat transfer nonlinearity coefficient n, which has a noticeable effect on the heating temperature curve, varies from device to device.
Economical energy consumption in the heating system can be achieved if certain requirements are met. One option is to have a temperature diagram, which reflects the ratio of the temperature emanating from the heating source to external environment. The values of the values make it possible to optimally distribute heat and hot water to the consumer.
High-rise buildings are mainly connected to central heating. The sources that transmit thermal energy are boiler houses or thermal power plants. Water is used as a coolant. It is heated to a given temperature.
Having passed full cycle According to the system, the coolant, already cooled, returns to the source and reheating occurs. Sources are connected to consumers by heating networks. Since the environment changes temperature, thermal energy should be adjusted so that the consumer receives the required volume.
Heat regulation from central system can be done in two ways:
- Quantitative. In this form, the water flow changes, but its temperature remains constant.
- Qualitative. The temperature of the liquid changes, but its flow does not change.
In our systems, the second regulation option 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 ensure the heat in the room is 18 degrees and above.
Hence, we can say that the temperature graph of the source is a broken curve. The change in its directions depends on temperature differences (coolant and outside air).
The dependency schedule may vary.
A specific diagram has a dependency on:
- Technical and economic indicators.
- CHP or boiler room equipment.
- Climate.
High coolant values provide the consumer with great thermal energy.
Below is an example of a diagram, where T1 is the coolant temperature, Tnv is the outside air:
A diagram of the returned coolant is also used. A boiler house or thermal power plant can estimate the efficiency of the source using this scheme. It is considered high when the returned liquid arrives chilled.
The stability of the scheme depends on the design values of fluid flow of high-rise buildings. If the flow through the heating circuit increases, the water will return uncooled, as the flow rate will increase. And vice versa, when minimum consumption, return water will be sufficiently cooled.
The supplier's interest, of course, is in the supply of return water in a cooled state. But there are certain limits for reducing consumption, since a decrease leads to loss of heat. The consumer’s internal temperature in the apartment will begin to drop, which will lead to a violation building codes and the discomfort of ordinary people.
What does it depend on?
The temperature curve depends on two quantities: outside air and coolant. Frosty weather leads to an increase in coolant temperature. When designing a central source, the size of the equipment, building and pipe size are taken into account.
The temperature leaving the boiler room is 90 degrees, so that at minus 23°C, the apartments are warm and have a value of 22°C. Then the return water returns to 70 degrees. Such standards correspond to normal and comfortable living in the house.
Analysis and adjustment of operating modes is carried out using a temperature diagram. For example, the return of liquid with an elevated temperature will indicate high coolant costs. Underestimated data will be considered a consumption deficit.
Previously, for 10-story buildings, a scheme with calculated data of 95-70°C was introduced. The buildings above had their own chart of 105-70°C. Modern new buildings may have a different layout 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 chart 95-70 How is it calculated?
A control method is selected, then a calculation is made. The calculated winter and reverse order of water supply, the amount of outside air, and the order at the break point of the diagram are taken into account. There are two diagrams: one of them considers only heating, the second considers heating with hot water consumption.
For an example of calculation, we will use methodological development"Roskommunenergo".
The input data for the heat generating station will be:
- Tnv– the amount of outside air.
- TVN- indoor air.
- T1– coolant from the source.
- T2– reverse flow of water.
- T3- entrance to the building.
We will look at several heat supply options with values of 150, 130 and 115 degrees.
At the same time, at the exit they will have 70°C.
The results obtained are compiled into a single table for 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 looked at the recommended values, excluding climatic features region and building characteristics.
To reduce energy consumption, just select a low temperature setting of 70 degrees and will be provided uniform distribution heat through the heating circuit. The boiler should be taken with a power reserve so that the system load does not affect quality work unit.
Adjustment
Heating regulator Automatic control is provided by the heating regulator.
It includes the following parts:
- Computing and matching panel.
- Actuator on the water supply section.
- Actuator, which performs the function of mixing liquid from the returned liquid (return).
- Boost pump and a sensor on the water supply line.
- Three sensors (on the return line, on the street, inside the building). There may be several of them in the room.
The regulator closes the liquid supply, thereby increasing the value between return and supply to the value specified by the sensors.
To increase the flow, there is a boost pump and a corresponding command from the regulator. The incoming flow is controlled by a "cold bypass". That is, the temperature decreases. Some of the liquid that has circulated along the circuit is sent to the supply.
Sensors collect information and transmit it to control units, resulting in a redistribution of flows that provide a rigid temperature scheme for the heating system.
Sometimes, a computing device is used that combines hot water and heating regulators.
The hot water regulator has more simple diagram management. The hot water sensor regulates the flow of water with a stable value of 50°C.
Advantages of the regulator:
- The temperature scheme is strictly maintained.
- Avoiding overheating of the liquid.
- Fuel efficiency and energy.
- The consumer, regardless of the distance, receives heat equally.
Table with temperature graph
The operating mode of boilers depends on the environmental weather.
If we take various objects, for example, a factory building, a multi-storey building and a private house, they will all have an individual thermal diagram.
In the table we show the temperature dependence diagram residential buildings from outside air:
| Outdoor temperature | Temperature of network water in the supply pipeline | Network water temperature in 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 standards that must be observed in the creation of projects for heating networks and the transportation of hot water to the consumer, where the supply of water steam must be carried out at 400°C, at a pressure of 6.3 Bar. It is recommended that the heat supply from the source be released to the consumer with values of 90/70 °C or 115/70 °C.
Regulatory requirements must be met in compliance with the approved documentation with mandatory approval from the Ministry of Construction of the country.
The supply of heat to a room is associated with a simple temperature schedule. The temperature values of the water supplied from the boiler room do not change in the room. They have standard values and range from +70ºС to +95ºС. This temperature schedule for the heating system is the most popular.
Adjusting the air temperature in the house
Not everywhere in the country there is centralized heating, so many residents install independent systems. Their temperature graph differs from the first option. In this case, temperature indicators are significantly reduced. They depend on the efficiency of modern heating boilers.
If the temperature reaches +35ºС, the boiler will operate at maximum power. It depends on the heating element, where thermal energy can be captured by exhaust gases. If the temperature values are greater than + 70 ºС, then the boiler performance drops. In that case, in his technical specifications efficiency is indicated at 100%.
Temperature schedule and its calculation
What the graph will look like depends on the outside temperature. The more negative the outside temperature, the greater the heat loss. Many people don’t know where to get it from this indicator. This temperature is prescribed in regulatory documents. The temperature of the coldest five-day period is taken as the calculated value, and the lowest value over the last 50 years is taken.
Graph of the dependence of external and internal temperatures The graph shows the relationship between external and internal temperatures. Let's say the outside temperature is -17ºС. Drawing a line upward until it intersects with t2, we obtain a point characterizing the temperature of the water in the heating system.
Thanks to the temperature schedule, you can prepare the heating system even for the most severe conditions. It also reduces material costs for installation heating system. If we consider this factor from the point of view of mass construction, the savings are significant.
inside premises depends from temperature coolant, A Also others factors:
- Outside air temperature. The smaller it is, the more negatively it affects heating;
- Wind. When strong wind occurs, heat loss increases;
- The temperature inside the room depends on the thermal insulation of the structural elements of the building.
Over the past 5 years, construction principles have changed. Builders increase the value of a home by insulating elements. As a rule, this applies to basements, roofs, and foundations. These expensive measures subsequently allow residents to save on the heating system.
Heating temperature chart The graph shows the dependence of the temperature of external and internal air. The lower the outside air temperature, the higher the coolant temperature in the system will be.
A temperature chart is developed for each city during heating season. In small settlements, a boiler room temperature schedule is drawn up, which provides the required amount of coolant to the consumer.
Change temperature schedule Can several ways:
- quantitative - characterized by a change in the flow rate of coolant supplied to the heating system;
- qualitative - consists of regulating the temperature of the coolant before supplying it to the premises;
- temporary - a discrete method of supplying water to the system.
The temperature curve is a schedule of heating pipes that distributes the heating load and is regulated by centralized systems. There is also an elevated schedule, it is created for closed system heating, that is, to ensure the supply of hot coolant to connected objects. When using an open system, it is necessary to adjust the temperature schedule, since the coolant is consumed not only for heating, but also for domestic water consumption.
The temperature graph is calculated using simple method. Hto build it, necessary initial temperature air data:
- external;
- in room;
- in the supply and return pipelines;
- at the exit of the building.
In addition, you should know the rated thermal load. All other coefficients are standardized by reference documentation. The system is calculated for any temperature schedule, depending on the purpose of the room. For example, for large industrial and civil facilities a schedule of 150/70, 130/70, 115/70 is drawn up. For residential buildings this figure is 105/70 and 95/70. The first indicator shows the supply temperature, and the second - the return temperature. The calculation results are entered into a special table, which shows the temperature at certain points of the heating system, depending on the outside air temperature.
The main factor when calculating the temperature schedule is the outside air temperature. The calculation table must be drawn up so that the maximum values of the coolant temperature in the heating system (graph 95/70) ensure heating of the room. Room temperatures are prescribed by regulatory documents.
heating devices
Heating device temperature The main indicator is the temperature of heating devices. The ideal temperature schedule for heating is 90/70ºС. It is impossible to achieve such an indicator, since the temperature inside the room should not be the same. It is determined depending on the purpose of the room.
In accordance with the standards, the temperature in the corner living room is +20ºС, in the rest – +18ºС; in the bathroom – +25ºС. If the outside air temperature is -30ºС, then the indicators increase by 2ºС.
Except Togo, exists norms For others types premises:
- in rooms where children are located – +18ºС to +23ºС;
- children's educational institutions – +21ºС;
- in cultural institutions with mass attendance – +16ºС to +21ºС.
This range of temperature values is compiled for all types of premises. It depends on the movements performed inside the room: the more of them, the lower temperature air. For example, in sports facilities people move a lot, so the temperature is only +18ºС.
Room temperature Exist certain factors, from which depends temperature heating devices:
- Outside air temperature;
- Type of heating system and temperature difference: for a single-pipe system – +105ºС, and for a single-pipe system – +95ºС. Accordingly, the differences in for the first region are 105/70ºС, and for the second – 95/70ºС;
- Direction of coolant supply to heating devices. With the top feed, the difference should be 2 ºС, with the bottom – 3 ºС;
- Type of heating devices: heat transfer is different, so the temperature curve will be different.
First of all, the coolant temperature depends on the outside air. For example, the temperature outside is 0ºC. In this case, the temperature regime in the radiators should be 40-45ºC at the supply, and 38ºC at the return. When the air temperature is below zero, for example -20ºС, these indicators change. In this case, the supply temperature becomes 77/55ºС. If the temperature reaches -40ºС, then the indicators become standard, that is, +95/105ºС at the supply, and +70ºС at the return.
Additional options
In order for a certain temperature of the coolant to reach the consumer, it is necessary to monitor the condition of the outside air. For example, if it is -40ºС, the boiler room should supply hot water with an indicator of +130ºС. Along the way, the coolant loses heat, but the temperature still remains high when it enters the apartments. Optimal value+95ºС. To do this, an elevator unit is installed in the basements, which serves to mix hot water from the boiler room and coolant from the return pipeline.
Several institutions are responsible for the heating main. The boiler room monitors the supply of hot coolant to the heating system, and the condition of the pipelines is monitored by city heating networks. The housing office is responsible for the elevator element. Therefore, to solve the problem of supplying coolant to a new house, you need to contact different offices.
Installation of heating devices is carried out in accordance with regulatory documents. If the owner himself replaces the battery, then he is responsible for the operation of the heating system and changes in temperature conditions.
Adjustment methods
Dismantling elevator unit If the boiler room is responsible for the parameters of the coolant leaving the warm point, then the housing office workers must be responsible for the temperature inside the room. Many residents complain about the cold in their apartments. This occurs due to a deviation in the temperature graph. In rare cases, it happens that the temperature rises by a certain value.
Heating parameters can be adjusted in three ways:
- Reaming the nozzle.
If the supply and return coolant temperatures are significantly underestimated, then it is necessary to increase the diameter of the elevator nozzle. This way, more liquid will pass through it.
How to do this? To begin with, it overlaps shut-off valves(house valves and taps at the elevator unit). Next, the elevator and nozzle are removed. Then it is drilled out by 0.5-2 mm, depending on how much it is necessary to increase the temperature of the coolant. After these procedures, the elevator is mounted in its original location and put into operation.
To ensure sufficient tightness of the flange connection, it is necessary to replace the paronite gaskets with rubber ones.
- Silence the suction.
In severe cold weather, when the problem of freezing of the heating system in the apartment arises, the nozzle can be completely removed. In this case, the suction may become a jumper. To do this, you need to plug it with a steel pancake 1 mm thick. This process is carried out only in critical situations, since the temperature in pipelines and heating devices will reach 130ºC.
- Adjustment of difference.
In the middle of the heating season, a significant increase in temperature may occur. Therefore, it is necessary to regulate it using a special valve on the elevator. To do this, the supply of hot coolant is switched to the supply pipeline. A pressure gauge is mounted on the return line. Adjustment occurs by closing the valve on the supply pipeline. Next, the valve opens slightly, and the pressure should be monitored using a pressure gauge. If you simply open it, the cheeks will sag. That is, an increase in pressure drop occurs in the return pipeline. Every day the indicator increases by 0.2 atmospheres, and the temperature in the heating system must be constantly monitored.
Heat supply. Video
How is the heat supply of private and apartment buildings, you can find out from the video below.
When drawing up a heating temperature schedule, it is necessary to take into account various factors. This list includes not only structural elements building, but the outside temperature, as well as the type of heating system.
In contact with
Looking through the statistics of visits to our blog, I noticed that search phrases such as, for example, “what should be the coolant temperature at minus 5 outside?” appear very often. I decided to post the old schedule for the quality regulation of heat supply based on the average daily outside air temperature. I would like to warn those who, based on these figures, will try to figure out the relationship with housing departments or heating networks: heating schedules for each individual settlement different (I wrote about this in the article regulating the coolant temperature). Heating networks in Ufa (Bashkiria) operate according to this schedule.
I would also like to draw your attention to the fact that regulation occurs based on the average daily outside air temperature, so if, for example, it is minus 15 degrees outside at night and minus 5 during the day, then the coolant temperature will be maintained in accordance with the schedule at minus 10 oC.
Typically, the following temperature schedules are used: 150/70, 130/70, 115/70, 105/70, 95/70. The schedule is selected depending on specific local conditions. House heating systems operate according to schedules 105/70 and 95/70. Main heating networks operate according to schedules 150, 130 and 115/70.
Let's look at an example of how to use a chart. Let's say the temperature outside is minus 10 degrees. Heating network operate according to a temperature schedule of 130/70, which means that at -10 °C the coolant temperature in the supply pipeline of the heating network should be 85.6 degrees, in the supply pipeline of the heating system - 70.8 °C with a schedule of 105/70 or 65.3 °C with a schedule of 95 /70. The water temperature after the heating system should be 51.7 °C.
As a rule, the temperature values in the supply pipeline of heating networks are rounded when assigned to a heat source. For example, according to the schedule it should be 85.6 °C, but at a thermal power plant or boiler house it is set to 87 degrees.
| 53,2 | 50,2 | 46,4 | 43,4 | 41,2 | 35,8 |
| 55,7 | 52,3 | 48,2 | 45,0 | 42,7 | 36,8 |
| 58,1 | 54,4 | 50,0 | 46,6 | 44,1 | 37,7 |
| 60,5 | 56,5 | 51,8 | 48,2 | 45,5 | 38,7 |
| 62,9 | 58,5 | 53,5 | 49,8 | 46,9 | 39,6 |
| 65,3 | 60,5 | 55,3 | 51,4 | 48,3 | 40,6 |
| 67,7 | 62,6 | 57,0 | 52,9 | 49,7 | 41,5 |
| 70,0 | 64,5 | 58,8 | 54,5 | 51,0 | 42,4 |
| 72,4 | 66,5 | 60,5 | 56,0 | 52,4 | 43,3 |
| 74,7 | 68,5 | 62,2 | 57,5 | 53,7 | 44,2 |
| 77,0 | 70,4 | 63,8 | 59,0 | 55,0 | 45,0 |
| 79,3 | 72,4 | 65,5 | 60,5 | 56,3 | 45,9 |
| 81,6 | 74,3 | 67,2 | 62,0 | 57,6 | 46,7 |
| 83,9 | 76,2 | 68,8 | 63,5 | 58,9 | 47,6 |
| 86,2 | 78,1 | 70,4 | 65,0 | 60,2 | 48,4 |
| 88,5 | 80,0 | 72,1 | 66,4 | 61,5 | 49,2 |
| 90,8 | 81,9 | 73,7 | 67,9 | 62,8 | 50,1 |
| 93,0 | 83,8 | 75,3 | 69,3 | 64,0 | 50,9 |
| 95,3 | 85,6 | 76,9 | 70,8 | 65,3 | 51,7 |
| 97,6 | 87,5 | 78,5 | 72,2 | 66,6 | 52,5 |
| 99,8 | 89,3 | 80,1 | 73,6 | 67,8 | 53,3 |
| 102,0 | 91,2 | 81,7 | 75,0 | 69,0 | 54,0 |
| 104,3 | 93,0 | 83,3 | 76,4 | 70,3 | 54,8 |
| 106,5 | 94,8 | 84,8 | 77,9 | 71,5 | 55,6 |
| 108,7 | 96,6 | 86,4 | 79,3 | 72,7 | 56,3 |
| 110,9 | 98,4 | 87,9 | 80,7 | 73,9 | 57,1 |
| 113,1 | 100,2 | 89,5 | 82,0 | 75,1 | 57,9 |
| 115,3 | 102,0 | 91,0 | 83,4 | 76,3 | 58,6 |
| 117,5 | 103,8 | 92,6 | 84,8 | 77,5 | 59,4 |
| 119,7 | 105,6 | 94,1 | 86,2 | 78,7 | 60,1 |
| 121,9 | 107,4 | 95,6 | 87,6 | 79,9 | 60,8 |
| 124,1 | 109,2 | 97,1 | 88,9 | 81,1 | 61,6 |
| 126,3 | 110,9 | 98,6 | 90,3 | 82,3 | 62,3 |
| 128,5 | 112,7 | 100,2 | 91,6 | 83,5 | 63,0 |
| 130,6 | 114,4 | 101,7 | 93,0 | 84,6 | 63,7 |
| 132,8 | 116,2 | 103,2 | 94,3 | 85,8 | 64,4 |
| 135,0 | 117,9 | 104,7 | 95,7 | 87,0 | 65,1 |
| 137,1 | 119,7 | 106,1 | 97,0 | 88,1 | 65,8 |
| 139,3 | 121,4 | 107,6 | 98,4 | 89,3 | 66,5 |
| 141,4 | 123,1 | 109,1 | 99,7 | 90,4 | 67,2 |
| 143,6 | 124,9 | 110,6 | 101,0 | 94,6 | 67,9 |
| 145,7 | 126,6 | 112,1 | 102,4 | 92,7 | 68,6 |
| 147,9 | 128,3 | 113,5 | 103,7 | 93,9 | 69,3 |
| 150,0 | 130,0 | 115,0 | 105,0 | 95,0 | 70,0 |
Please do not rely on the diagram at the beginning of the post - it does not correspond to the data from the table.
Temperature graph calculation
The method for calculating the temperature graph is described in the reference book “Adjustment and operation of water heating networks” (Chapter 4, paragraph 4.4, p. 153).
This is a rather labor-intensive and time-consuming process, since for each outdoor temperature several values need to be counted: T1, T3, T2, etc.
To our joy, we have a computer and a spreadsheet processor MS Excel. A work colleague shared with me a ready-made table for calculating the temperature graph. It was made at one time by his wife, who worked as an engineer for a group of modes in thermal networks.
Temperature chart calculation table in MS Excel
In order for Excel to calculate and build a graph, you just need to enter a few initial values:
- design temperature in the supply pipeline of the heating network T1
- design temperature in the return pipeline of the heating network T2
- design temperature in the supply pipe of the heating system T3
- Outside air temperature Тн.в.
- Indoor temperature Tv.p.
- coefficient “n” (as a rule, it is not changed and is equal to 0.25)
- Minimum and maximum slice of the temperature graph Slice min, Slice max.
Entering initial data into the temperature chart calculation table
All. nothing more is required from you. The calculation results will be in the first table of the sheet. It is highlighted with a bold frame.
The charts will also adjust to the new values.
Graphic image temperature chart
The table also calculates the temperature of direct network water taking into account wind speed.
Download temperature chart calculation
energoworld.ru
Appendix e Temperature chart (95 – 70) °С
| Design temperature outdoor | Water temperature in server pipeline | Water temperature in return pipeline | Estimated outside air temperature | Supply water temperature | Water temperature in return pipeline |
Appendix e
CLOSED HEAT SUPPLY SYSTEM
TV1: G1 = 1V1; G2 =G1; Q = G1(h2 –h3)
OPEN HEATING SYSTEM
WITH WATER DISCHARGE INTO THE DEAD-END DHW SYSTEM
TV1: G1 = 1V1; G2 = 1V2; G3 = G1 – G2;
Q1 = G1(h2 – h3) + G3(h3 –hх)
Bibliography
1. Gershunsky B.S. Basics of Electronics. Kyiv, Vishcha school, 1977.
2. Meerson A.M. Radio measuring equipment. – Leningrad: Energy, 1978. – 408 p.
3. Murin G.A. Thermal measurements. –M.: Energy, 1979. –424 p.
4. Spektor S.A. Electrical measurements of physical quantities. Tutorial. – Leningrad: Energoatomizdat, 1987. –320s.
5. Tartakovsky D.F., Yastrebov A.S. Metrology, standardization and technical means measurements. – M.: Higher School, 2001.
6. Heat meters TSK7. Manual. – St. Petersburg: ZAO TEPLOKOM, 2002.
7. Calculator for the amount of heat VKT-7. Manual. – St. Petersburg: ZAO TEPLOKOM, 2002.
Zuev Alexander Vladimirovich
Adjacent files in the folder Technological measurements and instruments
studfiles.net
Heating temperature chart
The task of organizations servicing houses and buildings is to maintain standard temperatures. The heating temperature schedule directly depends on the outside temperature.
There are three heat supply systems
Graph of the dependence of external and internal temperatures - District heating a large boiler house (CHP), located at a considerable distance from the city. In this case, the heat supply organization, taking into account heat losses in networks, selects a system with a temperature schedule: 150/70, 130/70 or 105/70. The first number is the temperature of the water in the supply pipe, the second number is the temperature of the water in the return heat pipe.
- Small boiler houses located near residential buildings. In this case, the temperature schedule 105/70, 95/70 is selected.
- Individual boiler installed in a private house. The most acceptable schedule is 95/70. Although it is possible to reduce the supply temperature even further, since there will be practically no heat loss. Modern boilers operate automatically and support constant temperature in the supply heat pipe. The temperature chart of 95/70 speaks for itself. The temperature at the entrance to the house should be 95 °C, and at the exit - 70 °C.
IN Soviet times, when everything was state-owned, all parameters of temperature schedules were maintained. If according to the schedule the supply temperature should be 100 degrees, then that’s what it will be. This temperature cannot be supplied to residents, which is why elevator units were designed. Water from the return pipeline, cooled, was mixed into the supply system, thereby lowering the supply temperature to the standard one. In our times of general economy, the need for elevator units disappears. All heat supply organizations have switched to a 95/70 heating system temperature schedule. According to this graph, the coolant temperature will be 95 °C when the outside temperature is -35 °C. As a rule, the temperature at the entrance to the house no longer requires dilution. Therefore, all elevator units must be eliminated or reconstructed. Instead of conical sections, which reduce both the speed and volume of flow, install straight pipes. Plug the supply pipe from the return pipeline with a steel plug. This is one of the heat saving measures. It is also necessary to insulate the facades of houses and windows. Replace old pipes and batteries with new - modern ones. These measures will increase the air temperature in homes, which means you can save on heating temperatures. A drop in outside temperature is immediately reflected in residents' receipts.
heating temperature chart Majority Soviet cities built with an “open” heat supply system. This is when water from the boiler room reaches consumers in their homes and is used for personal needs and heating. When reconstructing systems and constructing new heat supply systems, a “closed” system is used. Water from the boiler room reaches a heating point in the microdistrict, where it heats the water to 95 °C, which goes to the house. This results in two closed rings. This system allows heat supply organizations to significantly save resources for heating water. After all, the volume of heated water leaving the boiler room will be almost the same at the entrance to the boiler room. No need to log into the system cold water.
Temperature charts are:
- optimal. The heat resource of the boiler room is used exclusively for heating houses. Temperature regulation occurs in the boiler room. Supply temperature – 95 °C.
- elevated. The heat resource of the boiler house is used for heating houses and hot water supply. Two-pipe system enters the house. One pipe is heating, the other pipe is hot water supply. Supply temperature 80 – 95 °C.
- adjusted. The heat resource of the boiler house is used for heating houses and hot water supply. A single pipe system fits into the house. The heat resource for heating and hot water for residents is taken from one pipe in the house. Supply temperature – 95 – 105 °C.
How to perform a heating temperature schedule. There are three ways:
- high-quality (coolant temperature regulation).
- quantitative (regulating the volume of coolant by turning on additional pumps on the return pipeline, or installing elevators and washers).
- qualitative and quantitative (to regulate both the temperature and volume of the coolant).
The quantitative method predominates, which is not always able to withstand the heating temperature schedule.
Fight against heat supply organizations. This fight is being waged by management companies. By law Management Company is obliged to conclude an agreement with the heat supply organization. Whether it will be a contract for the supply of heat resources or simply an agreement on interaction is decided by the management company. An appendix to this agreement will be a heating temperature schedule. The heat supply organization is required to approve temperature schemes with the city administration. The heat supply organization supplies the heat resource to the wall of the house, that is, to the metering units. By the way, the law establishes that heat engineers are required to install metering units in houses at their own expense with installment payments for residents. So, having metering devices at the entrance and exit of the house, you can control the heating temperature daily. We take the temperature table, look at the air temperature on the weather website and find in the table the indicators that should be there. If there are deviations you need to complain. Even if deviations in big side, residents will pay more. At the same time, the windows will be opened and the rooms will be ventilated. You should complain about insufficient temperature to the heat supply organization. If there is no response, we write to the city administration and Rospotrebnadzor.
Until recently, there was an increasing coefficient on the cost of heat for residents of houses that were not equipped with communal metering meters. Due to the sluggishness of management organizations and heating workers, ordinary residents suffered.
An important indicator in the heating temperature chart is the temperature indicator of the return pipeline of the network. In all graphs this is 70 °C. In severe frosts, when heat loss increases, heat supply organizations are forced to turn on additional pumps on the return pipeline. This measure increases the speed of water movement through the pipes, and, therefore, heat transfer increases and the temperature in the network is maintained.
Again, during a period of general savings, it is very problematic to force heat generators to turn on additional pumps, which means increasing energy costs.
The heating temperature schedule is calculated based on the following indicators:
- ambient temperature;
- supply pipeline temperature;
- return temperature;
- the amount of thermal energy consumed at home;
- required amount of thermal energy.
For different rooms The temperature schedule is different. For children's institutions (schools, kindergartens, art palaces, hospitals), the room temperature should be between +18 and +23 degrees according to sanitary and epidemiological standards.
- For sports premises – 18 °C.
- For residential premises - in apartments not lower than +18 °C, in corner rooms + 20 °C.
- For non-residential premises – 16-18 °C. Based on these parameters, heating schedules are constructed.
It is easier to calculate the temperature schedule for a private home, since the equipment is installed directly in the house. A thrifty owner will provide heating to the garage, bathhouse, outbuildings. The load on the boiler will increase. We calculate the heat load depending on the lowest possible air temperatures of previous periods. We select equipment by power in kW. The most cost-effective and environmentally friendly boiler is natural gas. If you have gas turned on, half the job is already done. You can also use gas in cylinders. At home, you don’t have to adhere to the standard temperature schedules of 105/70 or 95/70, and it doesn’t matter if the temperature in the return pipe is not 70 °C. Adjust the network temperature to your liking.
By the way, many city residents would like to put individual meters for heat and control the temperature schedule yourself. Contact heat supply organizations. And there they hear such answers. Most houses in the country are built according to vertical system heat supply. Water is supplied from bottom to top, less often from top to bottom. With such a system, the installation of heat meters is prohibited by law. Even if a specialized organization installs these meters for you, the heat supply organization simply will not accept these meters for operation. That is, there will be no savings. Installation of meters is possible only if horizontal wiring heating.
In other words, when the heating pipe comes into your home not from above, not from below, but from the entrance corridor - horizontally. Individual heat meters can be installed at the entry and exit points of heating pipes. The installation of such meters pays for itself in two years. All houses are now built with just such a wiring system. Heating devices are equipped with control knobs (taps). If you think the temperature in the apartment is high, you can save money and reduce the heating supply. We can only save ourselves from freezing.
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Temperature chart of the heating system: variations, application, shortcomings
The temperature graph of the heating system is 95 -70 degrees Celsius - this is the most popular temperature graph. By and large, we can say with confidence that all central heating systems operate in this mode. The only exceptions are buildings with autonomous heating.
But even in autonomous systems there may be exceptions when using condensing boilers.
When using boilers operating on the condensation principle, heating temperature curves tend to be lower.
Temperature in pipelines depending on outside air temperature
Application of condensing boilers
For example, when maximum load for a condensing boiler, the mode will be 35-15 degrees. This is explained by the fact that the boiler extracts heat from the flue gases. In a word, with other parameters, for example, the same 90-70, it will not be able to work effectively.
Distinctive properties of condensing boilers are:
- high efficiency;
- efficiency;
- optimal efficiency at minimum load;
- quality of materials;
- high price.
You have heard many times that the efficiency of a condensing boiler is about 108%. Indeed, the instructions say the same thing.
Valliant condensing boiler
But how can this be, since we are still school desk They taught that there is no more than 100%.
- The thing is that when calculating the efficiency of conventional boilers, 100% is taken as the maximum. But ordinary gas boilers To heat a private house, flue gases are simply released into the atmosphere, and condensation gases utilize part of the wasted heat. The latter will later be used for heating.
- The heat that will be recovered and used in the second round is added to the boiler efficiency. Typically, a condensing boiler utilizes up to 15% of flue gases, and it is this figure that is adjusted to the efficiency of the boiler (approximately 93%). The result is a number of 108%.
- Undoubtedly, heat recovery is necessary thing, but the boiler itself costs a lot of money for such work. High price boiler due to stainless steel heat exchange equipment, which utilizes heat in the last chimney tract.
- If instead of such stainless steel equipment you install ordinary iron equipment, it will become unusable in a very short period of time. Since the moisture contained in the exhaust gases has aggressive properties.
- main feature condensing boilers is that they achieve maximum efficiency with minimal loads. Conventional boilers (gas heaters), on the contrary, reach their peak efficiency at maximum load.
- The beauty of it useful property The point is that during the entire heating period, the heating load is not at its maximum all the time. For 5-6 days at most, a regular boiler works at maximum. Therefore, a conventional boiler cannot compare in performance with a condensing boiler, which has maximum performance at minimum loads.
You can see a photo of such a boiler just above, and a video of its operation can be easily found on the Internet.
Principle of operation
Conventional heating system
It is safe to say that the heating temperature schedule of 95 - 70 is the most in demand.
This is explained by the fact that all houses that receive heat supply from central heat sources are designed to operate in this mode. And we have more than 90% of such houses.
District boiler house
The operating principle of this heat generation occurs in several stages:
- heat source (district boiler house) produces water heating;
- heated water, through main and distribution networks moves towards consumers;
- in the consumer’s home, most often in the basement, through the elevator unit, hot water is mixed with water from the heating system, the so-called return water, the temperature of which is no more than 70 degrees, and is then heated to a temperature of 95 degrees;
- Then the heated water (the one that is 95 degrees) passes through the heating devices of the heating system, heats the rooms and again returns to the elevator.
Advice. If you have a cooperative house or a society of co-owners of houses, then you can set up the elevator yourself, but this requires strictly following the instructions and correctly calculating the throttle washer.
Poor heating of the heating system
Very often we hear that people’s heating does not work well and their rooms are cold.
There can be many reasons for this, the most common are:
- schedule temperature system heating is not provided, perhaps the elevator is incorrectly designed;
- house system the heating system is heavily contaminated, which greatly impairs the passage of water through the risers;
- cloudy heating radiators;
- unauthorized change of the heating system;
- poor thermal insulation of walls and windows.
A common mistake is an incorrectly designed elevator nozzle. As a result, the function of mixing water and the operation of the entire elevator as a whole is disrupted.
This could happen for several reasons:
- negligence and lack of training of operating personnel;
- incorrectly performed calculations in the technical department.
Over the years of operating heating systems, people rarely think about the need to clean their heating systems. By and large, this applies to buildings that were built during the Soviet Union.
All heating systems must pass hydropneumatic flushing before everyone heating season. But this is observed only on paper, since Housing Offices and other organizations carry out this work only on paper.
As a result, the walls of the risers become clogged, and the latter become smaller in diameter, which disrupts the hydraulics of the entire heating system as a whole. The amount of heat passed through decreases, that is, someone simply does not have enough of it.
You can do hydropneumatic blowing yourself, all you need is a compressor and the desire.
The same applies to cleaning radiators. Over many years of operation, radiators accumulate a lot of dirt, silt and other defects inside. Periodically, at least once every three years, you need to disconnect them and wash them.
Dirty radiators greatly reduce the heat output in your room.
The most common issue is unauthorized changes and redevelopment of heating systems. When replacing old metal pipes with metal-plastic ones, the diameters are not respected. Or even various bends are added, which increases local resistance and worsens the quality of heating.
Metal-plastic pipe
Very often, with such unauthorized reconstruction and replacement of heating batteries with gas welding, the number of radiator sections also changes. And really, why not give yourself more sections? But in the end, your housemate who lives after you will receive less of the heat he needs for heating. And the last neighbor who will suffer the most is the one who will lose the most warmth.
Plays an important role thermal resistance enclosing structures, windows and doors. Statistics show that up to 60% of the heat can escape through them.
Elevator unit
As we said above, all water-jet elevators are designed to mix water from the supply line of heating networks into the return of the heating system. Thanks to this process, system circulation and pressure are created.
As for the material used for their manufacture, both cast iron and steel are used.
Let's look at the principle of operation of the elevator using the photo below.
The principle of operation of the elevator
Through pipe 1, water from the heating networks passes through the ejector nozzle and with high speed enters mixing chamber 3. There water from the return water of the building's heating system is mixed with it, the latter is supplied through pipe 5.
The resulting water is sent to the heating system supply through diffuser 4.
In order for the elevator to function correctly, its neck must be correctly selected. To do this, calculations are made using the formula below:
Where ΔРs is the calculated circulation pressure in the heating system, Pa;
Gcm - water consumption in the heating system kg/h.
For your information! True, for such a calculation you will need a heating scheme for the building.
External view of the elevator unit
Have a warm winter!
Page 2
In the article we will find out how the average daily temperature is calculated when designing heating systems, how the temperature of the coolant at the exit of the elevator unit depends on the outside temperature, and what the temperature of the heating radiators can be in winter.
We will also touch on the topic of independently combating the cold in the apartment.
Cold in winter is a sore subject for many residents of city apartments.
general information
Here we present the main provisions and excerpts from the current SNiP.
Outdoor temperature
The calculated temperature of the heating period, which is included in the design of heating systems, is no less than the average temperature of the coldest five-day periods over the eight coldest winters of the last 50 years.
This approach allows, on the one hand, to be prepared for severe frosts, which happen only once every few years, on the other hand, do not invest excessive funds in the project. On the scale of mass development we are talking about very significant amounts.
Target room temperature
It is worth mentioning right away that the temperature in the room is affected not only by the temperature of the coolant in the heating system.
Several factors operate in parallel:
- Outside air temperature. The lower it is, the greater the heat leakage through walls, windows and roofs.
- Presence or absence of wind. Strong wind increases the heat loss of buildings by blowing through unsealed doors and windows in entrances, basements and apartments.
- The degree of insulation of the facade, windows and doors in the room. It is clear that in the case of a hermetically sealed metal-plastic window with a double-chamber double-glazed window, heat loss will be much lower than with a dried-out wooden window and glazing in two threads.
It’s interesting: now there is a trend towards the construction of apartment buildings with the maximum degree of thermal insulation. In Crimea, where the author lives, new houses are built immediately with facade insulation mineral wool or foam plastic and with hermetically sealed doors of entrances and apartments.
The external façade is covered with basalt fiber slabs.
- And, finally, the actual temperature of the heating radiators in the apartment.
So, what are the current temperature standards in rooms for various purposes?
- In the apartment: corner rooms- not lower than 20C, other living rooms - not lower than 18C, bathroom - not lower than 25C. A nuance: when the estimated air temperature is below -31C, more is taken for corner and other living rooms high values, +22 and +20С (source - Decree of the Government of the Russian Federation dated May 23, 2006 “Rules for the provision utilities citizens").
- IN kindergarten: 18-23 degrees depending on the purpose of the room for toilets, bedrooms and playrooms; 12 degrees for walking verandas; 30 degrees for indoor swimming pools.
- In educational institutions: from 16C for bedrooms of boarding schools to +21 in classrooms.
- In theaters, clubs, and other entertainment venues: 16-20 degrees for the auditorium and +22C for the stage.
- For libraries (reading rooms and book depositories) the norm is 18 degrees.
- In grocery stores, the normal winter temperature is 12, and in non-food stores - 15 degrees.
- The temperature in the gyms is maintained at 15-18 degrees.
For obvious reasons, there is no need for heat in the gym.
- In hospitals, the temperature maintained depends on the purpose of the room. For example, the recommended temperature after otoplasty or childbirth is +22 degrees, in the wards for premature babies it is maintained at +25, and for patients with thyrotoxicosis (excessive secretion of hormones thyroid gland) - 15C. In surgical wards the norm is +26C.
Temperature graph
What should be the temperature of the water in the heating pipes?
It is determined by four factors:
- Air temperature outside.
- Type of heating system. For single pipe system Maximum temperature water in the heating system according to current standards is 105 degrees, for a two-pipe system - 95. The maximum temperature difference between supply and return is 105/70 and 95/70C, respectively.
- The direction of water supply to the radiators. For upper filling houses (with supply in the attic) and lower filling houses (with a pairwise loop of risers and the location of both lines in the basement), the temperatures differ by 2 - 3 degrees.
- Type of heating appliances in the house. Radiators and gas convectors heating systems have different heat output; Accordingly, to ensure the same temperature in the room, the heating temperature regime must be different.
The convector is somewhat inferior to the radiator in thermal efficiency.
So, what should be the heating temperature - the water in the supply and return pipes - at different outside temperatures?
We present only a small part of the temperature table for design temperature ambient air -40 degrees.
- At zero degrees, the temperature of the supply pipe for radiators with different wiring is 40-45C, the return pipe is 35-38. For convectors 41-49 supply and 36-40 return.
- At -20 for radiators, the supply and return should have a temperature of 67-77/53-55C. For convectors 68-79/55-57.
- At -40C outside, for all heating devices the temperature reaches the maximum permissible: 95/105 depending on the type of heating system in the supply and 70C in the return pipeline.
Useful additions
To understand the operating principle of the heating system apartment building, division of areas of responsibility, you need to know a few more facts.
The temperature of the heating main at the exit from the thermal power plant and the temperature of the heating system in your home are completely different things. At the same -40, the thermal power plant or boiler house will produce about 140 degrees in the supply. Water does not evaporate only due to pressure.
At your home's elevator unit, some of the return water from your heating system is mixed into the supply. The nozzle injects a stream of hot water with high pressure into the so-called elevator and draws masses of cooled water into repeated circulation.
Schematic diagram of the elevator.
Why is this necessary?
To provide:
- Reasonable mixture temperature. Let us remind you: the heating temperature in the apartment cannot exceed 95-105 degrees.
Attention: for kindergartens there is a different temperature standard: no higher than 37C. Low temperature heating devices have to be compensated by a large heat exchange area. That is why in kindergartens the walls are decorated with such long radiators.
- Large volume of water involved in circulation. If you remove the nozzle and supply water directly from the supply, the return temperature will differ little from the supply, which will sharply increase heat loss along the route and disrupt the operation of the thermal power plant.
If you turn off the water suction from the return, the circulation will become so slow that the return pipeline may simply freeze in winter.
Areas of responsibility are divided as follows:
- The heat producer - the local thermal power plant or boiler house - is responsible for the temperature of the water pumped into the heating mains;
- For transportation of coolant from minimal losses- organization servicing heating networks (KTS - communal heating networks).
This condition of the heating mains, as in the photo, means huge heat losses. This is the area of responsibility of the CTS.
- For maintenance and adjustment of the elevator unit - Housing Department. In this case, however, the diameter of the elevator nozzle - what the temperature of the radiators depends on - is agreed upon with the CTS.
If your home is cold and all the heating appliances are those installed by the builders, you will resolve this issue with the homeowners. They are required to provide temperatures recommended by sanitary standards.
If you undertake any modification of the heating system, for example, replacing radiators with gas welding, you thereby assume full responsibility for the temperature in your home.
How to deal with the cold
Let's be realistic, however: most often you have to solve the problem of cold in an apartment yourself, with your own hands. Not always a housing organization can provide you with heat within a reasonable time, and sanitary standards will not satisfy everyone: you want your home to be warm.
What will the instructions for combating the cold in an apartment building look like?
Jumpers in front of radiators
In most apartments there are jumpers in front of the heating appliances, which are designed to ensure water circulation in the riser no matter the condition of the radiator. For a long time they were supplied three-way valves, then they began to install them without any shut-off valves.
In any case, the jumper reduces the circulation of coolant through the heating device. In the case when its diameter is equal to the diameter of the eyeliner, the effect is especially pronounced.
The simplest way to make your apartment warmer is to embed chokes into the jumper itself and the liner between it and the radiator.
Here the same function is performed ball valves. This is not entirely correct, but it will work.
With their help, it is possible to conveniently regulate the temperature of the heating radiators: with the jumper closed and the throttle to the radiator fully open, the temperature is maximum; as soon as you open the jumper and close the second throttle, the heat in the room goes away.
The great advantage of this modification is the minimal cost of the solution. The price of the throttle does not exceed 250 rubles; Squeegees, couplings and locknuts cost pennies.
Important: if the throttle leading to the radiator is even slightly closed, the throttle on the jumper opens completely. Otherwise, adjusting the heating temperature will result in the neighbors’ radiators and convectors cooling down.
Another useful change. With such an insert, the radiator will always be uniformly hot along its entire length.
Warm floor
Even if the radiator in the room is hanging on the return riser with a temperature of about 40 degrees, by modifying the heating system you can make the room warm.
The solution is low-temperature heating systems.
In a city apartment, it is difficult to use in-floor heating convectors due to the limited height of the room: raising the floor level by 15-20 centimeters will mean completely low ceilings.
A much more realistic option is a warm floor. Due to where larger area heat transfer and more rational distribution of heat throughout the room, low-temperature heating will warm the room better than a hot radiator.
What does the implementation look like?
- Chokes are installed on the jumper and liner in the same way as in the previous case.
- The outlet from the riser to the heating device is connected to metal-plastic pipe, which fits into the screed on the floor.
So that communications are not spoiled appearance rooms, they are put away in a box. As an option, the insert into the riser is moved closer to the floor level.
It’s not a problem to move the valves and chokes to any convenient place.
Conclusion
You can find additional information about the operation of centralized heating systems in the video at the end of the article. Warm winters!
Page 3
The heating system of a building is the heart of all engineering mechanisms of the entire house. It will depend on which components are selected:
- Efficiency;
- Economical;
- Quality.
Selection of sections for the room
All of the above qualities directly depend on:
- Heating boiler;
- Pipelines;
- Method of connecting the heating system to the boiler;
- Heating radiators;
- Coolant;
- Adjustment mechanisms (sensors, valves and other components).
One of the main points is the selection and calculation of heating radiator sections. In most cases, the number of sections is calculated by design organizations that develop full project building a house.
This calculation is influenced by:
- Materials of enclosing structures;
- Availability of windows, doors, balconies;
- Dimensions of premises;
- Room type ( living room, warehouse, corridor);
- Location;
- Orientation to cardinal directions;
- Location of the room being calculated in the building (corner or in the middle, on the first floor or last).
Data for calculations are taken from SNiP “Building Climatology”. Calculation of the number of sections of heating radiators according to SNiP is very accurate, thanks to it you can ideally calculate the heating system.
Looking through the statistics of visits to our blog, I noticed that search phrases such as, for example, very often appear “What should the coolant temperature be at minus 5 outside?”. I decided to post the old one schedule for qualitative regulation of heat supply based on average daily outside air temperature. I would like to warn those who, based on these figures, will try to figure out the relationship with housing departments or heating networks: heating schedules for each individual settlement are different (I wrote about this in the article). Heating networks in Ufa (Bashkiria) operate according to this schedule.
I also want to draw attention to the fact that regulation occurs according to average daily outside air temperature, so if, for example, outside at night minus 15 degrees, and during the day minus 5, then the coolant temperature will be maintained in accordance with the schedule at minus 10 o C.
Typically, the following temperature charts are used: 150/70 , 130/70 , 115/70 , 105/70 , 95/70 . The schedule is selected depending on specific local conditions. House heating systems operate according to schedules 105/70 and 95/70. Main heating networks operate according to schedules 150, 130 and 115/70.
Let's look at an example of how to use a chart. Let's say the temperature outside is minus 10 degrees. Heating networks operate according to a temperature schedule 130/70 , which means when -10 o C the temperature of the coolant in the supply pipeline of the heating network should be 85,6 degrees, in the supply pipe of the heating system - 70.8 o C with a 105/70 schedule or 65.3 o C with a 95/70 schedule. The water temperature after the heating system should be 51,7 about S.
As a rule, the temperature values in the supply pipeline of heating networks are rounded when assigned to a heat source. For example, according to the schedule it should be 85.6 o C, but at a thermal power plant or boiler house it is set to 87 degrees.
| Temperature outdoor air Tnv, o S |
Temperature of network water in the supply pipeline T1, o C |
Water temperature in the heating system supply pipe T3, o C |
Water temperature after the heating system T2, o C |
|||
|---|---|---|---|---|---|---|
| 150 | 130 | 115 | 105 | 95 | ||
| 8 | 53,2 | 50,2 | 46,4 | 43,4 | 41,2 | 35,8 |
| 7 | 55,7 | 52,3 | 48,2 | 45,0 | 42,7 | 36,8 |
| 6 | 58,1 | 54,4 | 50,0 | 46,6 | 44,1 | 37,7 |
| 5 | 60,5 | 56,5 | 51,8 | 48,2 | 45,5 | 38,7 |
| 4 | 62,9 | 58,5 | 53,5 | 49,8 | 46,9 | 39,6 |
| 3 | 65,3 | 60,5 | 55,3 | 51,4 | 48,3 | 40,6 |
| 2 | 67,7 | 62,6 | 57,0 | 52,9 | 49,7 | 41,5 |
| 1 | 70,0 | 64,5 | 58,8 | 54,5 | 51,0 | 42,4 |
| 0 | 72,4 | 66,5 | 60,5 | 56,0 | 52,4 | 43,3 |
| -1 | 74,7 | 68,5 | 62,2 | 57,5 | 53,7 | 44,2 |
| -2 | 77,0 | 70,4 | 63,8 | 59,0 | 55,0 | 45,0 |
| -3 | 79,3 | 72,4 | 65,5 | 60,5 | 56,3 | 45,9 |
| -4 | 81,6 | 74,3 | 67,2 | 62,0 | 57,6 | 46,7 |
| -5 | 83,9 | 76,2 | 68,8 | 63,5 | 58,9 | 47,6 |
| -6 | 86,2 | 78,1 | 70,4 | 65,0 | 60,2 | 48,4 |
| -7 | 88,5 | 80,0 | 72,1 | 66,4 | 61,5 | 49,2 |
| -8 | 90,8 | 81,9 | 73,7 | 67,9 | 62,8 | 50,1 |
| -9 | 93,0 | 83,8 | 75,3 | 69,3 | 64,0 | 50,9 |
| -10 | 95,3 | 85,6 | 76,9 | 70,8 | 65,3 | 51,7 |
| -11 | 97,6 | 87,5 | 78,5 | 72,2 | 66,6 | 52,5 |
| -12 | 99,8 | 89,3 | 80,1 | 73,6 | 67,8 | 53,3 |
| -13 | 102,0 | 91,2 | 81,7 | 75,0 | 69,0 | 54,0 |
| -14 | 104,3 | 93,0 | 83,3 | 76,4 | 70,3 | 54,8 |
| -15 | 106,5 | 94,8 | 84,8 | 77,9 | 71,5 | 55,6 |
| -16 | 108,7 | 96,6 | 86,4 | 79,3 | 72,7 | 56,3 |
| -17 | 110,9 | 98,4 | 87,9 | 80,7 | 73,9 | 57,1 |
| -18 | 113,1 | 100,2 | 89,5 | 82,0 | 75,1 | 57,9 |
| -19 | 115,3 | 102,0 | 91,0 | 83,4 | 76,3 | 58,6 |
| -20 | 117,5 | 103,8 | 92,6 | 84,8 | 77,5 | 59,4 |
| -21 | 119,7 | 105,6 | 94,1 | 86,2 | 78,7 | 60,1 |
| -22 | 121,9 | 107,4 | 95,6 | 87,6 | 79,9 | 60,8 |
| -23 | 124,1 | 109,2 | 97,1 | 88,9 | 81,1 | 61,6 |
| -24 | 126,3 | 110,9 | 98,6 | 90,3 | 82,3 | 62,3 |
| -25 | 128,5 | 112,7 | 100,2 | 91,6 | 83,5 | 63,0 |
| -26 | 130,6 | 114,4 | 101,7 | 93,0 | 84,6 | 63,7 |
| -27 | 132,8 | 116,2 | 103,2 | 94,3 | 85,8 | 64,4 |
| -28 | 135,0 | 117,9 | 104,7 | 95,7 | 87,0 | 65,1 |
| -29 | 137,1 | 119,7 | 106,1 | 97,0 | 88,1 | 65,8 |
| -30 | 139,3 | 121,4 | 107,6 | 98,4 | 89,3 | 66,5 |
| -31 | 141,4 | 123,1 | 109,1 | 99,7 | 90,4 | 67,2 |
| -32 | 143,6 | 124,9 | 110,6 | 101,0 | 94,6 | 67,9 |
| -33 | 145,7 | 126,6 | 112,1 | 102,4 | 92,7 | 68,6 |
| -34 | 147,9 | 128,3 | 113,5 | 103,7 | 93,9 | 69,3 |
| -35 | 150,0 | 130,0 | 115,0 | 105,0 | 95,0 | 70,0 |
Please do not rely on the diagram at the beginning of the post - it does not correspond to the data from the table.
Temperature graph calculation
The method for calculating the temperature graph is described in the reference book (Chapter 4, paragraph 4.4, p. 153).
This is a rather labor-intensive and time-consuming process, since for each outdoor temperature you need to count several values: T 1, T 3, T 2, etc.
To our joy, we have a computer and a spreadsheet processor MS Excel. A work colleague shared with me a ready-made table for calculating the temperature graph. It was made at one time by his wife, who worked as an engineer for a group of modes in thermal networks.
In order for Excel to calculate and build a graph, you just need to enter a few initial values:
- design temperature in the supply pipeline of the heating network T 1
- design temperature in the return pipeline of the heating network T 2
- design temperature in the heating system supply pipe T 3
- Outdoor temperature T n.v.
- Indoor temperature T v.p.
- coefficient " n"(it is, as a rule, unchanged and equal to 0.25)
- Minimum and maximum cut of the temperature graph Cut min, Cut max.
All. nothing more is required from you. The calculation results will be in the first table of the sheet. It is highlighted with a bold frame.
The charts will also adjust to the new values.
The table also calculates the temperature of direct network water taking into account wind speed.