Before purchasing any heating radiator, you need to know the required thermal power of this device. Actually, based on this data, the number of sections is selected. Skipping the calculation stage may ultimately result in a disruption of the microclimate in the room, so it would be useful to familiarize yourself with the calculation methodology.

About the calculation of the heating system

At this stage it is necessary to ensure that thermal power The heating radiator ensured a constant temperature in the room during the coldest times heating season. Determining the power of the heating radiator is necessary in order to determine the required number of segments ().

Note! To be able to smoothly regulate the operation of the heating battery, it is not superfluous to install a thermostat.

The whole process is carried out in several stages:

• heat losses through the enclosing structures are calculated;
• By technical documentation the heat transfer of one segment of the selected radiator is determined;
• The required number of battery segments is calculated.

Heat loss calculation

This is the first place to start when it comes to how to determine the power of a heating radiator.

Heat is consumed through:

• walls, both external and internal (if the room borders unheated room);
• ceiling;
• windows and doors.

Calculation of losses is carried out taking into account the type and thickness of the material, the formula is used

in this formula

• Q – heat loss;
• S – room area, m2;
• Δt – temperature difference inside and outside the room, ᵒС;
• λ – reference value – thermal conductivity coefficient, W/m∙ᵒС;
• v – thickness of the enclosing structure, m.

From the point of view of heat loss, the upper floors are at a disadvantage, because there is an unheated attic above them, and the wind outside is stronger. So for them, the resulting heat loss can be increased by about 10%.

Note! When calculating, you must not forget about ventilation, because air exchange does not stop in winter. To do this, a multiplying factor of 1.1 – 1.4 is introduced. Greater importance is taken for intensive ventilation of housing.

Radiator calculation

Having data on thermal losses in hand, you can proceed to selecting a battery. In this case, it is necessary to take into account the efficiency of the device, for example, power steel radiators heating is inferior to bimetallic analogues.

The required number of segments is determined as the ratio of heat losses to the heat transfer of one segment. But the heat transfer of a section is a rated value; the manufacturer is required to indicate it for each radiator model. The formula used is:

in this formula:

• n – total number of battery sections, pcs;
• Q – heat loss, W;
• N – power of one section, W.

It should be taken into account that the rating data on the power of the 1st segment are given for a certain temperature difference (most often 90/70). But quite often the temperature of the coolant differs, and in this case the heat transfer heating battery changes. For example, power cast iron radiators heating when changing the temperature pressure from 80-100 to 50-60 drops by about 15-20%.

To calculate the power of a segment at an arbitrary temperature drop, use the formula

in this formula

• k – heat transfer, rated value, W/m 2 ∙ᵒС;

• A – section area, m2;
• ΔТ – temperature difference, ᵒС. Calculated by the formula

T under and T arr – coolant temperature at the inlet and outlet of the battery, respectively, ᵒС;

T room – room temperature, ᵒС.

Simplified technique

If all the work in the house is done with your own hands, then quite often, instead of a detailed calculation, people are content with an approximate selection. It should be noted that the result in this case, although not particularly accurate, is suitable for selecting a radiator.

There are several ways to make an approximate calculation:

• with standard parameters (ceiling height in the room up to 3 m, coolant temperature 85-90ᵒC, 1 window and 1 door in the room), you can use the dependence of 100 W/1 m 2 area. For a room with an area of, for example, 20 m2, you need a battery that can provide thermal power of 2 kW;

Note! For corner rooms, as well as apartments on the upper floors, an increasing factor of 1.2 is introduced. The price of batteries is not that high, so it is better to be on the safe side.

• The calculation can be carried out taking into account the cubic capacity of the room. In this case, we proceed from the proportion that 200 W of thermal power can heat 5 m 3 of room space.

Note! Practice shows that the result in this case is overestimated by about 10%.

The results from both methods should be approximately the same. It is more convenient to compare them using a specific example. Suppose you need to choose a radiator for a room measuring 5x5x3 meters, it has 1 double-glazed window, 1 interior door, the apartment is on the ground floor.

The first simplified calculation method involves the following sequence of actions:

• the area of ​​the room is determined, 5x5 = 25m2;
• taking into account the proportion of 100 W/1 m 2, the power of the device is determined, in our case 2.5 kW;
• The power of one section of a particular radiator is written out from the passport characteristics. For example, let's choose the aluminum model A350, 1 segment is capable of delivering 138 W of thermal energy;
• the number of segments is calculated, 2500/138 = 18.12≈19 pieces.

Note! The connection method also plays a big role in the uniformity of its heating, and therefore the amount of heat transfer.

When working according to the 2nd method, the instructions will look like this:

• Taking into account the proportion of 200 W/5 m3, we determine how much air will heat 1 section of the selected battery. In our case, 1 section will heat 3.45 m3;
• determine the volume of the room 5∙5∙3 = 75 m 3 ;
• the number of sections is calculated: 75/3.45 ≈ 22 sections.

The error when calculating using 2 simplified methods was 13.6%, which is not so bad for an approximate calculation. The results obtained are approximately consistent with the recommendations of the manufacturer itself (indicated in the table).

Summarizing

To maintain a normal indoor microclimate, it is necessary to achieve a balance between heat gain and loss. This condition can only be met with proper calculation. heating system in general and heating radiators in particular. The calculation methods proposed in the article may well be used when selecting the number of sections of a heating battery in an apartment or private house ().

The video is brief instructions according to the calculation of the heating battery.

The design of any heating system begins with the calculation of its basic parameters. First of all, this concerns the optimal load on the heat supply. Therefore, before purchasing necessary equipment you should make a calculation of the power of the heating system: boilers, radiators, pumps, batteries.

Why is a heating calculation necessary?

The defining task of performing calculations is to optimize further costs. The minimum required power of the heating boiler will directly affect energy consumption. But savings should be within reason.

The main purpose of heat supply is to maintain a comfortable temperature level in residential premises. This is influenced by the rated power of cast iron heating radiators, heat losses buildings and boiler parameters.

To select the equipment correctly, you must correctly calculate its parameters. This can be done using specialized programs or independently using certain formulas.

• Planning costs for purchasing equipment. The higher the rated power of the boiler or the heat output of the battery, the higher their cost. As a result, this will affect the budget of the entire heating supply arrangement;
• Correct scheduling of system load. Correct calculation of the power of the heating pump will allow you to find out the maximum and minimum load on the equipment when changing external factors– temperature outside, in the rooms of the house;
• System modernization. If observed high costs heating costs, reducing them is a top priority to minimize maintenance. To do this, calculate the power of the heating battery and other components.

Having decided that without calculating the basic data you cannot begin purchasing materials and components for the arrangement of heat supply, you should select calculation methods. First, the characteristics of each component separately are determined - the boiler, the radiator pump. Their parameters are then entered into the heating program and checked again. The same method is used to calculate the heating of the greenhouse.

For power calculation gas boiler heating is influenced by the type of energy carrier used. It is necessary to decide in advance what type of gas will be used - main gas or liquefied.

Determination of heat losses at home

At the first stage, it is necessary to correctly calculate the amount of heat that will escape through the external walls, windows and doors of the building. The heat supply operation must compensate for these losses and, based on the data obtained, further calculations of the power of the circulation pump for heating, boiler and batteries will be performed.

The determining parameter is the heat transfer resistance of the walls and window designs. This is the inverse indicator of the thermal conductivity of materials. It is impossible to select the power of a heating boiler without knowing these values. Therefore, before starting calculations, you should find out the thickness of the walls and the material from which they are made.

It is recommended to familiarize yourself with the contents of SNiP II-3-79, as well as SNiP 02/23/2003. These documents indicate standard values ​​of heat transfer resistance for various regions of Russia. Knowing them, you can solve the question of how to calculate the power of a heating radiator. Each material has a specific heat transfer value. Data on the most common residential buildings for construction can be taken from standard tables.

But this is not enough to further calculate the power of steel heating radiators. Additionally, you will need to know the thickness of each type of material used to build the walls. The ratio of this value to the heat transfer coefficient will be the desired value:

Where R– heat transfer resistance; D– material thickness; Λ – heat transfer resistance.

In the future, this will be used to calculate the required power of the heating boiler. This calculation step is recommended. Only by knowing the actual wall resistance can you determine the rated power of the entire heating system.

During the calculation, the wind rose characteristic of each specific region is not taken into account. Data about it affects the calculation only for multi-storey buildings.

Features of calculating the power of various heating boilers

For correct selection The power of the heating boiler is determined in advance by its installation location, the type of heating system (open, closed) and the type of fuel used. Additionally taken into account total area home and its volume. This data will allow you to make calculations in several ways.

The easiest method to calculate rated power heating equipment– use only the area of ​​the house. To do this, take the standard ratio that to heat 10 m² of space you need to spend 1 kW of thermal energy. This method will only work for buildings with good thermal insulation and standard height ceilings. Its disadvantage is the large error. So, for a house with an area of ​​150 m², according to the calculation of the heating boiler power, you will need to choose a 15 kW model.

Additionally, a correction factor is applied, which depends on the location of the building. Then the final formula for calculating the power of a gas heating boiler will look like this:

W=(S/10)*K

Where W– rated power of the boiler; S– area of ​​the house; K- correction factor.

For the central regions of Russia K=0.13; for northern latitudes this value varies from 0.15 to 0.2. When selecting the power of a heating boiler for the southern regions, K = 0.08.

Accurate calculations can be made only after preliminary determination of the heat transfer coefficient of the walls. This technique was described above. First, we find the temperature difference between the heated air outside and in the house – Δt. Then it is necessary to determine the heat losses. They are found according to the formula:

Р=Δt/R

Where R– heat losses at home; Δt– temperature difference; R– heat transfer resistance coefficient.

Next, to calculate the power of a gas heating boiler, it is necessary to multiply the area of ​​the external walls by heat losses. As an example, let's take a house with a wall area of ​​127 m², the heat transfer resistance coefficient is 0.502. Optimal valueΔt should be 55. In this case, heat loss per 1 m² will be equal to:

Р=55/0.505=108 W/m²

W=127*108=13.7 kW

Subsequently, the load on the heating system is determined at different meaningsΔt. It is recommended to choose an equipment model with a small power reserve - 10-15%. This will allow expanding the heat supply without replacing the boiler and radiators.

For apartments with normal insulation, you can take the ratio of 41 W of heat per 1 m³ of room volume in panel house and 38 W in brick. If the walls have been thermally insulated, you will need to make the calculation described above.

Calculation of the power of radiators and radiators

But in addition to the boiler, the performance of the heat supply is affected by the technical characteristics of other components. Therefore, you need to know how to calculate the power of a heating battery. In fact, thermal energy transfer occurs in it from hot water indoor air.

To calculate the power of heating batteries, it is necessary to actually determine their heat transfer. This is the name given to the process of transferring heat from a heated body to air into a room. There are several factors that influence this indicator. The main one is the material of manufacture. How less resistance heat transfer of the battery - the lower the thermal losses. However, along with this, the effect of energy accumulation must be taken into account. This is observed in cast iron structures. Since to calculate the power of a heating battery, you need to know its filling level hot water– the total area of ​​the structure should be calculated. The total heat transfer also depends on this.

For calculations, it is necessary to determine Δt using the following formula:

Δt=((Tpod-Tobr)/2)-Tpom

Where Tpod, Tobr And Tpom– temperatures in the supply and return pipes and in the room.

To calculate the power of cast iron heating radiators, you will need the thermal conductivity coefficient of a specific material and the total area of ​​the structure. The first can be taken from standard tables. For bimetallic models, when calculating the power of a heating radiator, steel pipeline cores and an aluminum heating surface are taken into account.

The calculation is performed using the following formula:

Q=Δt*k*S

Where Q – specific heat radiator; TO- coefficient of thermal conductivity; S– total area of ​​the structure.

In this way you can calculate the power of the heating battery. However, in practice this is difficult, since several factors remain unknown - the actual wall thickness, additional elements, used in manufacturing. Also, when calculating the power of a heating battery, heat losses in the room are not taken into account.

Most manufacturers indicate the rated power in the radiator data sheet. But this is only done for one thermal regime heating operation. Therefore, using the product’s passport data as a basis, you can accurately calculate the power of the heat supply radiator.

The actual heat output of the battery depends on how it is installed correctly. When calculating the power of steel heating radiators, their location relative to the window sill, floor and walls in the room is not taken into account.

Calculation of circulation pump power

IN closed systems heat supply, liquid circulation is forced. Before calculating the power of the heating pump, it is necessary to draw up a heat supply diagram. Only after this can you begin to calculate.

There are several parameters that determine the main characteristics of this heating component. The operation of the pump is aimed at increasing the speed of coolant movement in the system. In addition, it should not create excessive hydraulic loads or increase noise. This is why it is so important to correctly calculate the power of the heating pump.

To perform calculations, you will need to know the following equipment characteristics:

• Performance. It characterizes the amount of heat transferred per unit time through pipelines using a circulation pump;
• Hydraulic resistance. These are pressure losses in the lines due to friction of water against inner surface heating components. When calculating the power of a heating pump, this indicator is one of the determining ones, since the coolant flow rate depends on it;
• Power consumption. Indicated by the manufacturer in the device passport. Determined by the characteristics of the electric motor connected to the pump rotor.

At the first stage of calculating the power of the circulation pump for heating, the performance should be calculated. To do this, you will need to find out the required thermal power of the heating system. Performance calculations are performed using the following formula:

Q=(0.86*R)/(Tsub-Tob)

Where Q– device performance; R– design thermal power, W; Tpod And Tob– water temperature in the heating supply and return pipes.

The main factor influencing pump performance is the thermal power of the system. It is best to calculate it as accurately as possible to avoid purchasing a device with inappropriate parameters. The calculation of pump power for heat supply is also influenced by the characteristics of the coolant. If antifreeze is used, the nominal value must be increased by 10-15%, since their density is much higher than that of distilled water.

The hydraulic resistance of the circulation pump is determined by the following formula:

Н=1.3*(R1*L1+ R2*L2+… Z1+Z2)/10000

Where R1 And R2– pressure loss on the supply and return sections of the pipeline; L1 And L2– length of pipelines; Z1 And Z2– hydraulic resistance of system components.

For a conventional heating system with operating pressure up to 3 atm. one-story house, or a couple of floors, almost any radiators that are commercially available will do. For apartment multi-storey building, with coolant supply through vertical riser, where the pressure can reach 10 atm., radiators designed for a pressure of 12 atm are needed.

A distinctive feature of batteries for a gravity heating system is the minimum internal hydraulic resistance, so aluminum or cast iron devices are better suited there.

In general, the choice of radiators is not difficult, but it remains to choose them according to power. But here you will have to work a little and decide how much power will be needed in each room.

What method is most often used to determine the power of radiators?

If a thermal calculation of the cottage has not been done, which is a common occurrence, then the radiators need to be distributed among the rooms using an approximate calculation. But it is difficult to make a serious mistake that needs to be corrected by rewiring.

It is necessary to ensure that the power of all radiators is 20 percent greater than the heat loss of the building, i.e. boiler power. And for each room - according to its individual heat losses.

For a building insulated in accordance with the standard (SNiP 23-02-2003), heat loss can be considered 10 kW per 100 sq. m. area, if the ceiling height is up to 2.7 m. And if the building is not insulated enough... - then you need to insulate, and not increase the power of the heating system.

What thermal power will be required

It is not permissible to underestimate the power of radiators in comparison with the heat loss of the building. But it is not recommended to increase it too much.

• Firstly, this will entail unnecessary financial costs and cluttering of the room space with heating devices.
• Secondly, the thermal head may begin to close and open the radiator too often, which is harmful for the system as a whole.

Low temperature mode is useful when the batteries do not heat up to maximum temperature, respectively, have a reserve in size and power.

We know the total power of the radiators. Now it needs to be scattered across the rooms, where there is more, where there is less.

Selection of batteries for each room

Calculating batteries for each room only by area is not at all correct. After all, heat loss will depend on the availability and area external walls, windows and doors (external enclosing structures).



You can use a simplified radiator power distribution diagram:

• For an interior room, heat loss is minimal and radiators are usually not installed there.
• One outer wall and one window - we accept 1 kW per 10 sq. m.
• One external wall (long) and two windows - we multiply the result at the rate of 1 kW per 10 sq. m. by a factor of 1.2;
• Two external walls and one window - multiply by a correction factor of 1.3;
• Two external walls and two windows – 1.4 – 1.5.

But this is far from a correct distribution. Everything depends, of course, on the specific layout, i.e. on the actual length of the external walls and the area of ​​the windows and their thermal insulation.

Example - how to choose heating for each room

Let's look at an example. Let's say there are two rooms with the same area.
One room has only one external wall, 3 meters long.
Another room is corner, the length of its external walls is 3 meters + 6 meters + available big windows.



Obviously, heat loss in the second room will be significantly greater than in the first. In the first room, you may need to install one 1.5 kW radiator, and in the second room two radiators 1.5 kW and 2.0 kW, i.e. 2.2 times more powerful. And in a narrow internal corridor with the same area, most likely a radiator is not needed at all...

It is necessary on the building plan to distribute the total power of the radiators among the rooms, remembering that they are installed under each window (and if not possible, then next to it), and also preferably at front door, but are not placed behind furniture, in deep niches, etc.

Selection of power at the time of purchase

Now all that remains is to select a radiator based on power when purchasing in a store. But in technical specifications There is one feature of the radiator that is often not paid attention to, and therefore batteries of insufficient power are chosen.



It is often indicated in the passport for high-temperature heating. For example, 1500 W is indicated under conditions of 90/70-20, which means:

• Supply temperature – 90 degrees;
• Return temperature – 70 degrees;
• The air temperature in the room is 20 degrees.

And only under these conditions will the radiator deliver the required 1500 W.

Now in a private house no one will heat the coolant to 90 degrees C. Modern gas boilers It is recommended to set it to the most economical low-temperature mode, when the outlet from the boiler is 60 degrees, maximum 65. At the same time, the efficiency of the boiler is maximum, since a larger percentage of heat from the gases will be transferred to the cold coolant.

A comfortable temperature in the room 22 - 24 degrees. It's rare that anyone stays at a cool 20 degrees.

Therefore, the actual operating mode of the radiator is often 60/40-22. And at this temperature, the output power will be at least 33% lower.

How do specialists purchase radiators?

Consequently, radiators for low-temperature conditions, as the most economical, must be purchased at least a third more powerful than those indicated in the technical specifications for high-temperature conditions.

Experienced plumbers, without further ado, without taking into account the costs of the owners, having estimated the approximate heat loss of the room, they immediately multiply them by another 1.3 - 1.5 and demand to purchase radiators based on this power - according to the principle “to be sure.”

But you also can’t go overboard with increasing the power of the radiators, since the boiler can go to low-temperature heating, below the dew point (at the return less than +55 degrees), which is extremely undesirable. Falling dew on the heat exchanger will quickly destroy an ordinary boiler for any coolant.

At the same time, super-economical condensing boilers are precisely designed to operate in this mode.