Heating schedule for quality regulation of heat supply based on the average daily outdoor temperature. What is the temperature graph of the heating system and what does it depend on

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

For example, the entry 90-70ᵒС means that for given climatic conditions for heating a certain building, it will be necessary that the coolant at the inlet to the pipes has a temperature of 90ᵒС, and at the exit 70ᵒС.

All values ​​are presented for the outside air temperature for the coldest five-day period. This design temperature is taken according to the joint venture " Thermal protection buildings." According to the norms, the internal temperature for residential premises is 20ᵒС. The schedule will ensure the correct supply of coolant to the heating pipes. This will avoid hypothermia of the premises and waste of resources.

The need to perform constructions and calculations

A temperature chart must be developed for each locality.It allows you to provide the most competent work heating systems, namely:

1. Adjust the heat losses during the supply of hot water to houses with the average daily outdoor temperature.
2. Prevent insufficient heating of rooms.
3. oblige thermal stations to supply consumers with services that meet technological conditions.

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

Ways to control the temperature in the heating system

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

• quantitative;
• quality;
• temporary.

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

For the central heating system, the most characteristic is a qualitative method, while the volume of water entering the heating circuit, remains unchanged.

Graph types

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

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

The adjusted schedule is also intended for networks operating both for heating and for heating. Here, heat losses are taken into account when the coolant passes through the pipes to the consumer.

Drawing up a temperature chart

The constructed straight line depends on the following values:

• normalized air temperature in the room;
• outdoor air temperature;
• the degree of heating of the coolant when it enters the heating system;
• the degree of heating of the coolant at the outlet of the building networks;
• the degree of heat transfer of heating devices;
• thermal conductivity of the outer walls and the overall heat loss of the building.

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

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

Calculation of the heating mode

First of all, you need to get all the initial data. Standard values ​​of temperatures of external and internal air are accepted according to the joint venture "Thermal protection of buildings". To find the power of heating devices and heat losses, you will need to use the following formulas.

Heat loss of the building

In this case, the input data will be:

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

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

Thermal losses of walls are calculated by the formula:

Q = F*(1/R 0)*(t inside air -t outside air)

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

Calculation of the surface power of batteries

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

R beats \u003d R max / F act

Calculation of the coolant temperature

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

It is rather difficult to carry out calculations according to the method. To perform a competent calculation, it is best to use special programs.

For each building, such a calculation is carried out individually by the management company. For an approximate definition of water at the inlet to the system, you can use the existing tables.

1. For large suppliers of thermal energy, coolant parameters are used 150-70ᵒС, 130-70ᵒС, 115-70ᵒС.
2. For small systems with several apartment buildings parameters apply 90-70ᵒС (up to 10 floors), 105-70ᵒС (over 10 floors). A schedule of 80-60ᵒС can also be adopted.
3. When arranging an autonomous heating system for individual home it is enough to control the degree of heating with the help of sensors, you can not build a graph.

The performed measures allow determining the parameters of the coolant in the system at a certain point in time. By analyzing the coincidence of the parameters with the schedule, you can check the efficiency of the heating system. The temperature chart table also indicates the degree of load on the heating system.

When autumn confidently walks across the country, snow flies beyond the Arctic Circle, and in the Urals night temperatures stay below 8 degrees, then the word form “heating season” sounds appropriate. People recall past winters and try to figure out the normal temperature of the coolant in the heating system.

Prudent owners of individual buildings carefully revise the valves and nozzles of the boilers. Residents apartment building by October 1, they are waiting, like Santa Claus, a plumber from a management company. The ruler of valves and valves brings warmth, and with it - joy, fun and confidence in the future.

The Gigacalorie Path

Megacities sparkle with high-rise buildings. A cloud of renovation hangs over the capital. Outback prays on five-story buildings. Until demolished, the house has a calorie supply system.

The economy class apartment building is heated through a centralized heat supply system. Pipes enter the basement of the building. The supply of heat carrier is regulated by inlet valves, after which water enters the mud collectors, and from there it is distributed through risers, and from them it is supplied to batteries and radiators that heat housing.

The number of gate valves correlates with the number of risers. While doing repair work in a single apartment, it is possible to turn off one vertical, and not the whole house.

The spent liquid partially leaves through the return pipe, and partially is supplied to the hot water supply network.

degrees here and there

Water for the heating configuration is prepared at a CHP plant or in a boiler house. The norms of water temperature in the heating system are prescribed in the building rules: the component must be heated to 130-150 ° C.

The supply is calculated taking into account the parameters of the outside air. So, for the South Ural region, minus 32 degrees is taken into account.

To prevent the liquid from boiling, it must be supplied to the network under a pressure of 6-10 kgf. But this is a theory. In fact, most networks operate at 95-110 ° C, since the network pipes of most settlements are worn out and high pressure tear them up like a heating pad.

An extensible concept is the norm. The temperature in the apartment is never equal to the primary indicator of the heat carrier. Here, the elevator unit performs an energy-saving function - a jumper between the direct and return pipes. The norms for the temperature of the coolant in the heating system on the return in winter allow the preservation of heat at a level of 60 ° C.

The liquid from the straight pipe enters the elevator nozzle, mixes with return water and again goes into the house network for heating. The carrier temperature is lowered by mixing the return flow. What affects the calculation of the amount of heat consumed by residential and utility rooms.

Hot gone

Hot water temperature sanitary rules at the points of analysis should lie in the range of 60-75 ° C.

In the network, the coolant is supplied from the pipe:

• in winter - from the reverse, so as not to scald users with boiling water;
• in summer - with a straight line, since in summer the carrier is heated no higher than 75 ° C.

On being compiled temperature chart. The average daily return water temperature should not exceed the schedule by more than 5% at night and 3% during the day.

Parameters of distributing elements

One of the details of warming a home is a riser through which the coolant enters the battery or radiator from the temperature norms of the coolant in the heating system require heating in the riser in winter time in the range of 70-90 °C. In fact, the degrees depend on the output parameters of the CHP or boiler house. In the summer, when hot water is needed only for washing and showering, the range moves to the range of 40-60 ° C.

Observant people may notice that in a neighboring apartment, the heating elements are hotter or colder than in his own.

The reason for the temperature difference in the heating riser is the way the hot water is distributed.

In a single-pipe design, the heat carrier can be distributed:

• above; then the temperature on the upper floors is higher than on the lower ones;
• from below, then the picture changes to the opposite - it is hotter from below.

In a two-pipe system, the degree is the same throughout, theoretically 90 ° C in the forward direction and 70 ° C in the opposite direction.

Warm like a battery

Suppose that the structures of the central network are reliably insulated along the entire route, the wind does not walk through the attics, stairwells and basements, the doors and windows in the apartments are insulated by conscientious owners.

We assume that the coolant in the riser complies with the building regulations. It remains to find out what is the norm for the temperature of the heating batteries in the apartment. The indicator takes into account:

• outdoor air parameters and time of day;
• the location of the apartment in terms of the house;
• living or utility room in the apartment.

Therefore, attention: it is important, not what is the degree of the heater, but what is the degree of air in the room.

During the day in the corner rooms, the thermometer should show at least 20 ° C, and in the centrally located rooms 18 ° C is allowed.

At night, air in the dwelling is allowed to be 17 ° C and 15 ° C, respectively.

Theory of linguistics

The name "battery" is household, denoting a number of identical items. In relation to the heating of housing, this is a series of heating sections.

The temperature standards of heating batteries allow heating no higher than 90 ° C. According to the rules, parts heated above 75 ° C are protected. This does not mean that they need to be sheathed with plywood or bricked. Usually they put a lattice fence that does not interfere with air circulation.

Cast iron, aluminum and bimetallic devices are common.

Consumer choice: cast iron or aluminum

Aesthetics cast iron radiators- a parable in the language. They require periodic painting, as regulations require that the work surface be smooth and allow dust and dirt to be easily removed.

A dirty coating forms on the rough inner surface of the sections, which reduces the heat transfer of the device. But technical specifications cast iron products on high:

• little susceptible to water corrosion, can be used for more than 45 years;
• they have a high thermal power per 1 section, therefore they are compact;
• they are inert in heat transfer, therefore they smooth out temperature fluctuations in the room well.

Another type of radiators is made of aluminum. Lightweight construction, painted in the factory, does not require painting, easy to clean.

But there is a drawback that overshadows the advantages - corrosion in the aquatic environment. Certainly, inner surface heaters are insulated with plastic to avoid contact of aluminum with water. But the film may be damaged, then a chemical reaction will begin with the release of hydrogen, when an excess gas pressure is created, the aluminum device may burst.

The temperature standards of heating radiators are subject to the same rules as batteries: it is not so much the heating of a metal object that is important, but the heating of the air in the room.

In order for the air to warm up well, there must be sufficient heat removal from the working surface of the heating structure. Therefore, it is strongly not recommended to increase the aesthetics of the room with shields in front of the heating device.

Stairwell heating

Since we are talking about an apartment building, we should mention the stairwells. The norms for the temperature of the coolant in the heating system state: the degree measure on the sites should not fall below 12 ° C.

Of course, the discipline of the residents requires that the doors of the entrance group be closed tightly, that the transoms of the stair windows not be left open, that the glass be kept intact and that any problems be promptly reported to the management company. If the management company does not take timely measures to insulate the points of probable heat loss and maintain the temperature regime in the house, an application for recalculation of the cost of services will help.

Changes in heating design

Replacement of existing heating devices in the apartment is carried out with the obligatory coordination with the management company. Unauthorized change in the elements of warming radiation can disrupt the thermal and hydraulic balance of the structure.

The heating season will begin, a change in the temperature regime in other apartments and sites will be recorded. A technical inspection of the premises will reveal unauthorized changes in the types of heating devices, their number and size. The chain is inevitable: conflict - trial - fine.

So the situation is resolved like this:

• if not old ones are replaced with new radiators of the same size, then this is done without additional approvals; the only thing to apply to the Criminal Code is to turn off the riser for the duration of the repair;
• if new products differ significantly from those installed during construction, then it is useful to interact with the management company.

Heat meters

Let us recall once again that the heat supply network of an apartment building is equipped with heat energy metering units, which record both the consumed gigacalories and the cubic capacity of water passed through the house line.

In order not to be surprised by bills containing unrealistic amounts for heat at temperatures in the apartment below the norm, before the start of the heating season, check with the management company whether the meter is in working order, whether the verification schedule has been violated.

Looking through the statistics of visiting our blog, I noticed that search phrases such as, for example, “what should be the temperature of the coolant at minus 5 outside?” appear very often. I decided to lay out the old schedule for the quality regulation of heat supply based on the average daily outdoor temperature. I want to warn those who, on the basis of these figures, will try to sort out relations with the housing department or heating networks: the heating schedules for each individual settlement are different (I wrote about this in the article on regulating the temperature of the coolant). Work on this schedule heating network in Ufa (Bashkiria).

I also want to draw attention to the fact that regulation takes place according to the average daily outdoor 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 °C.

As a rule, the following temperature graphs are used: 150/70, 130/70, 115/70, 105/70, 95/70. The schedule is selected depending on the specific local conditions. House heating systems operate according to schedules 105/70 and 95/70. According to schedules 150, 130 and 115/70, main heat networks operate.

Let's look at an example of how to use the chart. Suppose the temperature outside is minus 10 degrees. Heating networks operate according to a temperature schedule of 130/70, which means that at -10 ° C the temperature of the coolant 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 at chart 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 heat networks are rounded off when setting the heat source. For example, according to the schedule, it should be 85.6 ° C, and 87 degrees are set at the CHP or boiler house.

Outside temperature

Temperature of network water in the supply pipeline T1, °С Temperature of water in the supply pipeline of the heating system Т3, °С Temperature of water after the heating system Т2, °С

150 130 115 105 95 8 7 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 -14 -15 -16 -17 -18 -19 -20 -21 -22 -23 -24 -25 -26 -27 -28 -29 -30 -31 -32 -33 -34 -35

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 focus on the diagram at the beginning of the post - it does not correspond to the data from the table.

Calculation of the temperature graph

The method for calculating the temperature graph is described in the handbook "Setting up and operation of water heating networks" (Chapter 4, p. 4.4, p. 153,).

This is a rather laborious and lengthy process, since several values ​​must be read for each outdoor temperature: T1, T3, T2, etc.

To our joy, we have a computer and a MS Excel spreadsheet. A colleague at work shared with me a ready-made table for calculating the temperature graph. She was once made by his wife, who worked as an engineer for a group of regimes in thermal networks.

Table for calculating the temperature graph in MS Excel

In order for Excel to calculate and build a graph, it is enough to enter several initial values:

• design temperature in the supply pipeline of the heating network T1
• design temperature in the return pipe of the heating network T2
• design temperature in the supply pipe of the heating system T3
• Outdoor air temperature Tn.v.
• Indoor temperature Tv.p.
• coefficient "n" (it is usually not changed and is equal to 0.25)
• Minimum and maximum cut of the temperature graph Cut min, Cut max.

Entering initial data into the table for calculating the temperature graph

All. nothing more is required of you. The results of the calculations will be in the first table of the sheet. It is highlighted in bold.

The charts will also be rebuilt for the new values.

Graphical representation of the temperature graph

The table also considers 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 outdoor temperature	Supply water temperature	Water temperature in return pipeline

Appendix e

CLOSED HEATING SYSTEM

TV1: G1 = 1V1; G2=G1; Q = G1(h2 –h3)

OPEN HEATING SYSTEM

WITH WATER TANK INTO A DEAD-END DHW SYSTEM

TV1: G1 = 1V1; G2 = 1V2; G3 = G1 - G2;

Q1 \u003d G1 (h2 - h3) + G3 (h3 - hх)

Bibliography

1. Gershunsky B.S. Fundamentals of electronics. Kyiv, Vishcha school, 1977.

2. Meyerson A.M. Radio-measuring equipment. - Leningrad.: Energy, 1978. - 408s.

3. Murin G.A. Thermotechnical measurements. -M.: Energy, 1979. -424 p.

4. Spector S.A. Electrical measurements physical quantities. Tutorial. - Leningrad.: Energoatomizdat, 1987. –320s.

5. Tartakovskii D.F., Yastrebov A.S. Metrology, standardization and technical means measurements. – M.: graduate School, 2001.

6. Heat meters TSK7. Manual. - St. Petersburg.: CJSC TEPLOKOM, 2002.

7. Calculator of the amount of heat VKT-7. Manual. - St. Petersburg.: CJSC TEPLOKOM, 2002.

Zuev Alexander Vladimirovich

Neighboring files in the Process Measurements and Instruments folder

studfiles.net

Heating temperature chart

The task of organizations serving houses and buildings is to maintain the standard temperature. The temperature curve of heating directly depends on the temperature outside.

There are three heating systems

Graph of outside and inside temperature

1. District heating a large boiler house (CHP), standing at a considerable distance from the city. In this case, the heat supply organization, taking into account the heat losses in the networks, chooses a system with a temperature curve: 150/70, 130/70 or 105/70. The first digit is the temperature of the water in the supply pipe, the second digit is the temperature of the water in the return pipe.
2. Small boiler houses, which are located near residential buildings. In this case, the temperature curve 105/70, 95/70 is selected.
3. Individual boiler installed on private house. The most acceptable schedule is 95/70. Although it is possible to reduce the supply temperature even more, since there will be practically no heat loss. Modern boilers operate in automatic mode and maintain a constant temperature in the supply heat pipe. The 95/70 temperature chart speaks for itself. The temperature at the entrance to the house should be 95 ° C, and at the exit - 70 ° C.

AT Soviet times when everything was state-owned, all the parameters of the temperature charts were maintained. If according to the schedule there should be a supply temperature of 100 degrees, then this will be so. Such a temperature cannot be supplied to residents, so elevator units were designed. Water from the return pipeline, cooled down, was mixed into the supply system, thereby lowering the supply temperature to the standard one. In our time of universal economy, the need for elevator nodes is no longer necessary. All heat supply organizations switched to the temperature chart of the heating system 95/70. 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 that reduce both the speed and volume of the flow, put straight pipes. Seal 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, windows. Change old pipes and batteries to new ones - modern ones. These measures will increase the air temperature in dwellings, which means you can save on heating temperature. Lowering the temperature on the street is immediately reflected in the residents in the receipts.

heating temperature chart

Most Soviet cities were built with an "open" heating system. This is when water from the boiler room comes directly to consumers in homes and is used for personal needs of citizens and heating. During the reconstruction of systems and the construction of new heating systems, a "closed" system is used. The water from the boiler house reaches the heating point in the microdistrict, where it heats the water to 95 °C, which goes to the houses. It turns out two closed rings. This system allows heat supply organizations to significantly save resources for heating water. Indeed, the volume of heated water leaving the boiler room will be almost the same at the entrance to the boiler room. There is no need to get cold water into the system.

Temperature charts are:

• optimal. The heat resource of the boiler room is used exclusively for heating houses. Temperature control takes place in the boiler room. The supply temperature is 95 °C.
• elevated. The heat resource of the boiler house is used for heating houses and hot water supply. A 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. One-pipe system approaches the house. From one pipe in the house, a heat resource is taken for heating and hot water for residents. Supply temperature - 95 - 105 °C.

How to carry out the temperature heating schedule. It is possible in three ways:

1. quality (regulation of the temperature of the coolant).
2. quantitative (regulation of the coolant volume by turning on additional pumps on the return pipeline, or installing elevators and washers).
3. qualitative-quantitative (to regulate both the temperature and the volume of the coolant).

The quantitative method prevails, which is not always able to withstand the heating temperature graph.

Fight against heat supply organizations. This struggle is waged by management companies. By law Management Company is obliged to conclude an agreement with the heat supply organization. Will it be a contract for the supply of heat resources or just an agreement on interaction, the management company decides. An annex to this agreement will be a temperature schedule for heating. The heat supply organization is obliged to approve temperature charts in the city administration. The heat supply organization supplies the heat resource to the wall of the house, that is, to the metering stations. By the way, the legislation establishes that thermal workers are obliged to install metering stations in houses at their own expense with an installment payment for residents. So, having metering devices at the entrance and exit from the house, you can control the heating temperature daily. We take the temperature table, look at the air temperature on the weather site and find in the table the indicators that should be. 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. It is necessary to 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 a multiplying coefficient on the cost of heat for residents of houses that were not equipped with common house meters. Due to the sluggishness of managing organizations and thermal workers, ordinary residents suffered.

An important indicator in the heating temperature chart is the return temperature of the network. In all graphs, this is an indicator of 70 ° C. In severe frosts, when heat losses increase, 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, the heat transfer increases, and the temperature in the network is maintained.

Again, during the period of general savings, it is very problematic to force thermal workers to turn on additional pumps, which means increasing electricity costs.

The heating temperature graph is calculated based on the following indicators:

• ambient air temperature;
• supply pipeline temperature;
• return pipeline temperature;
• the amount of heat energy consumed at home;
• required amount of thermal energy.

For different rooms temperature curve is different. For children's institutions (schools, gardens, palaces of art, hospitals), the temperature in the room should be between +18 and +23 degrees according to sanitary and epidemiological standards.

• For sports facilities– 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 built.

It is easier to calculate the temperature schedule for a private house, since the equipment is mounted right in the house. A zealous owner will provide heating to the garage, bathhouse, and outbuildings. The load on the boiler will increase. Counting heat load depending on the maximum low air temperatures of past periods. We select equipment by power in kW. The most cost-effective and environmentally friendly boiler is natural gas. If gas is brought to you, this is already half the battle done. You can also use bottled gas. At home, you do not have to adhere to standard temperature schedules of 105/70 or 95/70, and it does not matter that the temperature in the return pipeline is not 70 ° C. Adjust the network temperature to your liking.

By the way, many city dwellers would like to install individual heat meters and control the temperature schedule themselves. Contact the heat supply companies. And there they hear such answers. Most of the houses in the country are built on a vertical heating system. Water is supplied from the bottom - up, 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, savings will not work. Installation of meters is possible only with horizontal heating distribution.

In other words, when a heating pipe comes into your home not from above, not from below, but from the entrance corridor - horizontally. At the place of entry and exit of heating pipes, individual heat meters can be installed. Installation of such counters pays off in two years. All houses are now being built with just such a wiring system. Heating appliances are equipped with control knobs (taps). If the temperature in the apartment is high in your opinion, then you can save money and reduce the heating supply. Only ourselves we will save from freezing.

myaquahouse.com

Temperature chart of the heating system: variations, application, shortcomings

The temperature chart of the heating system 95 -70 degrees Celsius is the most demanded temperature chart. By and large, it can be said with certainty that all systems central heating work 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, the temperature curves of heating tend to be lower.

Temperature in pipelines depending on the outside air temperature

Application of condensing boilers

For example, at maximum load for a condensing boiler, there will be a mode of 35-15 degrees. This is due to the fact that the boiler extracts heat from the exhaust 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;
• profitability;
• 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 manual says the same thing.

Condensing boiler Valliant

But how can this be, because we are still with school desk taught that more than 100% does not happen.

1. The thing is that when calculating the efficiency of conventional boilers, 100% is taken as the maximum. But ordinary gas boilers for heating a private house, flue gases are simply thrown into the atmosphere, and condensing ones utilize part of the outgoing heat. The latter will go to heating in the future.
2. The heat that will be utilized and used in the second round is added to the efficiency of the boiler. Typically, a condensing boiler utilizes up to 15% of flue gases, this figure is adjusted to the efficiency of the boiler (approximately 93%). The result is a number of 108%.
3. Undoubtedly, heat recovery is a necessary thing, but the boiler itself costs a lot of money for such work. The high price of the boiler due to stainless heat exchange equipment, which utilizes heat in the last path of the chimney.
4. If instead of such stainless equipment we put ordinary iron equipment, then it will become unusable after a very short period of time. Since the moisture contained in the flue gases has aggressive properties.
5. main feature condensing boilers lies in the fact that they achieve maximum efficiency with minimum loads. Ordinary boilers (gas heaters), on the contrary, reach the peak of economy at maximum load.
6. The beauty of it useful property is that during the entire heating period, the load on heating is not always maximum. On the strength of 5-6 days, an ordinary boiler works at maximum. Therefore, a conventional boiler cannot match the performance of a condensing boiler, which has maximum performance at minimum loads.

You can see a photo of such a boiler a little higher, and a video with 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 from central heat sources are designed to work in this mode. And we have more than 90% of such houses.

District boiler house

The principle of operation of such heat production occurs in several stages:

• heat source (district boiler house), produces water heating;
• heated water, through the main and distribution networks, moves to consumers;
• in the house of consumers, most often in the basement, through the elevator unit, hot water is mixed with water from the heating system, the so-called return flow, the temperature of which is not more than 70 degrees, and then heated to a temperature of 95 degrees;
• further heated water (the one that is 95 degrees) passes through the heaters of the heating system, heats the premises 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 with your own hands, but this requires you to strictly follow the instructions and correctly calculate the throttle washer.

Poor 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:

• the temperature schedule of the heating system is not observed, the elevator may be incorrectly calculated;
• the house heating system is heavily polluted, which greatly impairs the passage of water through the risers;
• fuzzy heating radiators;
• unauthorized change of the heating system;
• poor thermal insulation of walls and windows.

A common mistake is an incorrectly dimensioned 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.

During the many years of operation of 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 be hydropneumatic flushing before each heating season. But this is observed only on paper, since ZhEKs and other organizations carry out these works only on paper.

As a result, the walls of the risers become clogged, and the latter become smaller in diameter, which violates the hydraulics of the entire heating system as a whole. The amount of transmitted heat decreases, that is, someone simply does not have enough of it.

You can do hydropneumatic purge with your own hands, it is enough to have a compressor and a desire.

The same applies to cleaning radiators. Over many years of operation, radiators inside accumulate a lot of dirt, silt and other defects. Periodically, at least once every three years, they need to be disconnected and washed.

Dirty radiators greatly impair the heat output in your room.

The most common moment is an unauthorized change and redevelopment of heating systems. When replacing old metal pipes with metal-plastic ones, diameters are not observed. And sometimes 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 receive less heat the most, will suffer the most.

An important role is played by the thermal resistance of building envelopes, windows and doors. As statistics show, up to 60% of heat can escape through them.

Elevator node

As we said above, all water-jet elevators are designed to mix water from the supply line of heating networks into the return line 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.

Consider the principle of operation of the elevator in the photo below.

The principle of operation of the elevator

Through branch pipe 1, water from heating networks passes through the ejector nozzle and enters the mixing chamber 3 at high speed. There, water from the return of the building's heating system is mixed with it, the latter is supplied through branch pipe 5.

The resulting water is sent to the heating system supply through diffuser 4.

In order for the elevator to function correctly, it is necessary that its neck be correctly selected. To do this, calculations are made using the formula below:

Where ΔРnas - design circulation pressure in the heating system, Pa;

Gcm - water consumption in the heating system kg / h.

Note! True, for such a calculation, you need a building heating scheme.

The appearance 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 outlet of the elevator unit depends on the temperature outside, and what the temperature of the heating batteries can be in winter.

We will also touch on the topic of self-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.

Outside temperature

The design temperature of the heating period, which is included in the design of heating systems, is nothing less than the average temperature of the coldest five-day periods for 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 should be noted right away that the temperature in the room is affected not only by the temperature of the coolant in the heating system.

Several factors are at work in parallel:

• Air temperature outside. The lower it is, the greater the heat leakage through walls, windows and roofs.
• Presence or absence of wind. A strong wind increases the heat loss of buildings, blowing porches, basements and apartments through unsealed doors and windows.
• The degree of insulation of the facade, windows and doors in the room. It is clear that in the case of a hermetically sealed plastic window with a two-chamber double-glazed window, heat loss will be much lower than with a dry one wooden window and glazing in two threads.

It is curious: now there has been a trend towards the construction of apartment buildings with the maximum degree of thermal insulation. In Crimea, where the author lives, new houses are being built immediately with facade insulation mineral wool or polystyrene and with hermetically closing doors of entrances and apartments.

The facade is covered from the outside 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. Nuance: when the design air temperature is below -31C for corner and other living rooms, higher values ​​are taken, +22 and +20C (source - Decree of the Government of the Russian Federation of 05/23/2006 "Rules for providing utilities citizens").
• AT kindergarten: 18-23 degrees depending on the purpose of the room for toilets, bedrooms and game rooms; 12 degrees for walking verandas; 30 degrees for indoor swimming pools.
• AT educational institutions: from 16C for boarding school bedrooms to +21 in classrooms.
• In theaters, clubs, other places of entertainment: 16-20 degrees for the auditorium and + 22C for the stage.
• For libraries (reading rooms and book depositories) the norm is 18 degrees.
• AT grocery stores normal winter temperature is 12, and in non-food - 15 degrees.
• The temperature in the gyms is maintained at 15-18 degrees.

For obvious reasons, the heat in the gym is useless.

• In hospitals, the maintained temperature 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 thyroid hormones) - 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:

1. Air temperature outside.
2. Type of heating system. For a single-pipe system, the maximum water temperature in the heating system in accordance with 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.
3. The direction of the water supply to the radiators. For houses of the upper bottling (with supply in the attic) and lower (with pairwise looping of the risers and the location of both threads in the basement), the temperatures differ by 2 - 3 degrees.
4. Type of heating appliances in the house. Radiators and gas heating convectors have different heat transfer; accordingly, to ensure the same temperature in the room, the temperature regime of heating must be different.

The convector somewhat loses to the radiator in terms of thermal efficiency.

So, what should be the temperature of heating - water in the supply and return pipes - at different outdoor temperatures?

We give only a small part of the temperature table for the estimated ambient temperature of -40 degrees.

• At zero degrees, the temperature of the supply pipeline for radiators with different wiring is 40-45C, the return one is 35-38. For convectors 41-49 supply and 36-40 return.
• At -20 for radiators, the supply and return must have a temperature of 67-77 / 53-55C. For convectors 68-79/55-57.
• At -40C outside, for all heaters, the temperature reaches the maximum allowable temperature: 95/105, depending on the type of heating system, at the supply and 70C at the return pipe.

Useful extras

To understand the principle of operation of the heating system of an apartment building, the division of areas of responsibility, you need to know a few more facts.

The temperature of the heating main at the outlet from the CHP and the temperature of the heating system in your home are completely different things. At the same -40, a CHP or boiler house will produce about 140 degrees at the supply. Water does not evaporate only due to pressure.

AT elevator node In your home, part of the water from the return pipeline returning from the heating system is mixed into the supply. The nozzle injects a jet of hot water at high pressure into the so-called elevator and recirculates the masses of cooled water.

Schematic diagram of the elevator.

Why is this needed?

To provide:

1. Reasonable mixture temperature. Recall: the heating temperature in the apartment cannot exceed 95-105 degrees.

Attention: for kindergartens, a different temperature norm applies: 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 radiators of such great length.

1. Large volume of water involved in circulation. If you remove the nozzle and let the water flow directly from the supply, the return temperature will differ little from the supply, which will dramatically increase heat loss along the route and disrupt the operation of the CHP.

If you stop the suction of water from the return, the circulation will become so slow that the return pipeline can simply freeze in winter.

The areas of responsibility are divided as follows:

• The temperature of the water injected into the heating mains is the responsibility of the heat producer - the local CHP or boiler house;
• For the transportation of the coolant with minimal losses - the organization serving the heating networks (KTS - communal heating networks).

Such a state of heating mains, as in the photo, means huge heat losses. This is the area of ​​responsibility of the KTS.

• For maintenance and adjustment of the elevator unit - housing department. In this case, however, the diameter of the elevator nozzle - something on which the temperature of the radiators depends - is coordinated with the CTC.

If your house is cold and all the heating devices are those installed by the builders, you will settle this issue with the residents. They are required to provide the temperatures recommended by sanitary standards.

If you undertake any modification of the heating system, for example, replacing the heating batteries with gas welding, you thereby assume full responsibility for the temperature in your home.

How to deal with the cold

Let us, however, be realistic: most often we have to solve the problem of cold in the apartment ourselves, with our own hands. Not always a housing organization can provide you with heat in a reasonable time, and sanitary norms not everyone will be satisfied: I want the house to be warm.

What will the instructions for dealing with cold in an apartment building look like?

Jumpers in front of radiators

In front of the heaters in most apartments there are jumpers that are designed to ensure the circulation of water in the riser in any condition of the radiator. For a long time they were supplied with three-way valves, then they began to be installed without any shut-off valves.

The jumper in any case reduces the circulation of the coolant through the heater. 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 insert chokes into the jumper itself and the connection between it and the radiator.

Here, ball valves perform the same function. It's not entirely correct, but it will work.

With their help, it is possible to conveniently adjust the temperature of the heating batteries: when the jumper is closed and the throttle to the radiator is fully open, the temperature is maximum, it is worth opening the jumper and covering the second throttle - and the heat in the room comes to naught.

The great advantage of such a refinement is the minimum cost of the solution. The price of the throttle does not exceed 250 rubles; spurs, couplings and locknuts cost a penny at all.

Important: if the throttle leading to the radiator is at least slightly covered, the throttle on the jumper opens completely. Otherwise, adjusting the heating temperature will result in batteries and convectors that have cooled down at the neighbors.

Another helpful change. With such a tie-in, the radiator will always be evenly hot along the entire length.

Warm floor

Even if the radiator in the room hangs on a return riser with a temperature of about 40 degrees, by modifying the heating system, you can make the room warm.

An output - low-temperature systems of heating.

In a city apartment, it is difficult to use underfloor heating convectors due to the limited height of the room: raising the floor level by 15-20 centimeters will mean completely low ceilings.

Much more real option- warm floor. Due to where larger area heat transfer and more rational distribution heat in the volume of the room low-temperature heating will warm the room better than a red-hot radiator.

What does the implementation look like?

1. Chokes are placed on the jumper and the eyeliner in the same way as in the previous case.
2. The outlet from the riser to the heater is connected to metal-plastic pipe, which fits into the screed on the floor.

So that communications do not spoil appearance rooms, they are put away in a box. As an option, the tie-in to the riser is moved closer to the floor level.

It is not a problem at all to transfer the valves and throttles to any convenient place.

Conclusion

You can find more information about the operation of centralized heating systems in the video at the end of the article. warm winters!

Page 3

The building heating system is the heart of all engineering and technical mechanisms of the whole house. Which of its components will be selected will depend on:

• Efficiency;
• Profitability;
• 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 sections of heating radiators. In most cases, the number of sections is calculated by design organizations that develop a complete project for building a house.

This calculation is affected by:

• Enclosing materials;
• The presence of windows, doors, balconies;
• Room dimensions;
• Type of premises (living room, warehouse, corridor);
• Location;
• Orientation to the cardinal points;
• Location in the building of the calculated room (corner or in the middle, on the first floor or last).

The data for the calculation are taken from the SNiP "Construction Climatology". The calculation of the number of sections of heating radiators according to SNiP is very accurate, thanks to which you can perfectly calculate the heating system.

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

What it is

Let's start with a couple of abstract theses.

• With change weather conditions heat losses of any building change after them. In frosts, in order to maintain a constant temperature in the apartment, much more thermal energy is required than in warm weather.

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

• The heat flow from the heater at a constant coolant temperature will also be constant.
  A drop in room temperature will slightly increase it (again, due to an increase in the delta between the coolant and the air in the room); however, this increase will be categorically insufficient to compensate for the increased heat loss through the building envelope. Simply because the current SNiP limits the lower temperature threshold in 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 growth should be proportional to the decrease in street temperature: the colder it is outside the window, the greater the heat loss will have to be compensated. Which, in fact, brings us to the idea of ​​creating a specific table for matching both values.

So, the temperature chart 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 it all works

There are two different types charts:

1. For heating networks.
2. For domestic heating system.

To clarify the difference between these concepts, it is probably worth starting with a brief digression into how central heating works.

CHP - heat networks

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

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

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

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

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

House

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

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

By the way: in preschool educational institutions, the restriction is much 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.

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

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

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

Climate zones

The main factor that determines the scheduling algorithm is the estimated winter temperature. The heat carrier temperature table should be drawn up in such a way that the maximum values ​​\u200b\u200b(95/70 and 105/70) at the peak of frost provide the temperature in residential premises corresponding to SNiP.

Here is an example of an intra-house schedule for the following conditions:

• Heating devices - radiators with a coolant supply from the bottom up.
• Heating - two-pipe, co.

• The estimated outdoor air temperature is -15 C.

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

Nuance: when determining the parameters of the route and the in-house heating system, the average daily temperature is taken.
If it is -15 at night and -5 during the day, as outdoor temperature appear -10C.

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

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

In the photo - winter in Verkhoyansk.

Adjustment

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

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

Nozzle reaming

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

The instruction is at the service of the reader.

1. All valves or gates in the elevator unit are closed (inlet, house and hot water).
2. The elevator is dismantled.
3. The nozzle is removed and reamed by 0.5-1 mm.
4. The elevator is assembled and started with air bleeding in the reverse order.

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

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

Suction suppression

In a critical situation (strong cold and freezing apartments), the nozzle can be completely removed. So that the suction does not become a jumper, it is suppressed with a pancake from steel sheet not less than a millimeter thick.

Attention: this is an emergency measure applied 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 with a valve.

1. The DHW is switched to the supply pipe.
2. A manometer is installed on the return.
   
3. The inlet gate valve on the return pipeline closes completely and then gradually opens with pressure control on the pressure gauge. If you just close the valve, the subsidence of the cheeks on the stem can stop and unfreeze the circuit. The difference is reduced by increasing the return pressure by 0.2 atmospheres per day with daily temperature control.

Conclusion

Computers have been successfully working for a long time not only on the desks of office workers, but also in industrial and technological process control systems. Automation successfully manages the parameters of building heat supply systems, providing inside them ...

The set required air temperature (sometimes changing during the day to save money).

But the automation must be correctly configured, give it the initial data and algorithms for work! This article discusses the optimal temperature heating schedule - the dependence of the temperature of the coolant of the water heating system at various outdoor temperatures.

This topic has already been discussed in the article about. Here we will not calculate the heat losses of the object, but consider the situation when these heat losses are known from previous calculations or from the data of the actual operation of the operating object. If the facility is operating, then it is better to take the value of heat loss at the calculated outdoor temperature 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 outdoor air temperature, a system of nonlinear equations is solved by a numerical method. This article will present "direct" formulas for calculating water temperatures on the "supply" and on the "return", which is 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 in Excel of the temperature graph of heating.

So, when setting up the boiler and / or thermal node from the outside air temperature, the automation system must set a temperature graph.

Perhaps it would be more correct to place the air temperature sensor inside the building and adjust the operation of the coolant temperature control system based on the temperature of the indoor air. But it is often difficult to choose a location for installing the sensor inside due to different temperatures in different rooms of the facility or because of the significant remoteness of this place from the heating unit.

Consider an example. Let's say we have an object - a building or a group of buildings that receives thermal energy from one common closed source of heat supply - a boiler house and / or a thermal unit. A closed source is a source from which the selection of hot water for water supply is prohibited. In our example, we will assume that, in addition to the direct selection of hot water, there is no heat extraction for heating water for hot water supply.

To compare and verify the correctness of the calculations, we take the initial data from the above article "Calculation of water heating in 5 minutes!" and compose in Excel a small program for calculating the heating temperature graph.

Initial data:

1. Estimated (or actual) heat loss of an object (building) Q p in Gcal/h at design outdoor air temperature t nr write down

to cell D3: 0,004790

2. Estimated air temperature inside the object (building) t time in °C enter

to cell D4: 20

3. Estimated outdoor temperature t nr in °C we enter

to cell D5: -37

4. Estimated supply water temperature 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 non-linearity of heat transfer of applied heating devices n write down

to cell D8: 0,30

7. The current (of interest to us) outdoor temperature t n in °C we enter

to cell D9: -10

Values ​​in cellsD3 – D8 for a specific object are written once and then do not change. Cell valueD8 can (and should) be changed by determining the coolant parameters for different weather.

Calculation results:

8. Estimated water flow in the system GR in t/h 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. The temperature of the water at the "supply" 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 tabout 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

tabout = tvr -0,5*(tetc – top )* q +0,5*(tetc + top -2* tvr )* q (1/(1+ n ))

Calculation in Excel of the water temperature at the "supply" tP and on the return tabout for selected outdoor temperature tn completed.

Let's make a similar calculation for several different outdoor temperatures and build a heating temperature graph. (You can read about how to build graphs in Excel.)

Let's reconcile the obtained values ​​​​of the heating temperature graph with the results obtained in the article "Calculation of water heating in 5 minutes!" - the values ​​match!

Results.

The practical value of the presented calculation of the heating temperature graph lies in the fact that it takes into account the type of installed devices and the direction of movement of the coolant in these devices. Heat transfer non-linearity coefficient n, which has a noticeable effect on the temperature graph of heating for different devices is different.