One of the main goals preparatory activities Before installing the heating system, determine how many heating devices will be needed in each room, and what power they should have. Before calculating the number of radiators, it is recommended that you familiarize yourself with the basic techniques of this procedure.
Calculation of heating radiator sections by area
This is the simplest type of calculation of the number of sections of heating radiators, where the volume of heat required to heat the room is determined based on the square meters of the home.
- The average climate zone requires 60-100 W to heat 1 m2 of housing.
- For northern regions, this norm corresponds to 150-200 W.
With these numbers in hand, the required heat is calculated. For example, for apartments middle zone heating a room with an area of 15 m2 will require 1500 W of heat (15x100). It should be understood that we are talking about average standards, so it is better to focus on the maximum indicators for a particular region. For areas with very mild winters, a coefficient of 60 W can be used.
When making a power reserve, it is advisable not to overdo it, as this will require the use large number heating devices. Consequently, the volume of required coolant will also increase. For residents apartment buildings With central heating this question is not fundamental. Residents of the private sector have to increase the cost of heating the coolant, against the backdrop of increasing inertia of the entire circuit. This implies the need for careful calculation of heating radiators by area.
After determining all the heat needed for heating, it becomes possible to find out the number of sections. The accompanying documentation for any heating device contains information about the heat it produces. To calculate the sections, the total volume of heat required must be divided by the battery power. To see how this happens, you can refer to the example already given above, where, as a result of the calculations, the required volume for heating a room of 15 m2 was determined - 1500 W.
Let’s take the power of one section as 160 W: it turns out that the number of sections will be 1500:160 = 9.375. In which direction to round is the user's choice. Usually, the presence of indirect sources of heating the room and the degree of its insulation are taken into account. For example, in the kitchen the air is also heated household appliances during cooking, so you can round down there.
The method for calculating sections of heating radiators by area is characterized by considerable simplicity, however, a number of serious factors will disappear from view. These include the height of the premises, the number of door and window openings, the level of wall insulation, etc. Therefore, the method of calculating the number of radiator sections according to SNiP can be called approximate: in order to get a result without errors, you cannot do without corrections.
Room volume
This calculation approach also involves taking into account the height of the ceilings, because The entire volume of air in the home is subject to heating.
The calculation method used is very similar - first the volume is determined, after which the following standards are used:
- For panel houses heating 1 m3 of air requires 41 W.
- A brick house requires 34 W/m3.
For clarity, you can calculate the heating radiators of the same room of 15 m2 to compare the results. Let’s take the height of the home to be 2.7 m: in the end the volume will be 15x2.7 = 40.5.
Calculation for different buildings:
- Panel house. To determine the heat required for heating, 40.5 m3x41 W = 1660.5 W. To calculate the required number of sections 1660.5:170 = 9.76 (10 pcs.).
- Brick house. The total volume of heat is 40.5 m3x34 W = 1377 W. Radiator count – 1377:170 = 8.1 (8 pcs.).
It turns out that for heating brick house significantly fewer sections will be required. When the calculation of radiator sections per area was carried out, the result was averaged - 9 pieces.
We adjust the indicators
To more successfully solve the question of how to calculate the number of radiators per room, it is necessary to take into account some additional factors that contribute to an increase or decrease in heat loss. The material used to make the walls and the level of their thermal insulation have a significant influence. The number and size of windows, the type of glazing used for them, external walls, etc. also play a significant role. To simplify the procedure for calculating a radiator for a room, special coefficients are introduced.
Window
Approximately 15-35% of heat is lost through window openings: this is influenced by the size of the windows and the degree of their insulation. This explains the presence of two coefficients.
Window to floor area ratio:
- 10% - 0,8
- 20% - 0,9
- 30% - 1,0
- 40% - 1,1
- 50% - 1,2
By type of glazing:
- 3-chamber double-glazed windows or 2-chamber double-glazed windows with argon - 0.85;
- standard 2-chamber double-glazed window - 1.0;
- simple double frames - 1.27.
Walls and roof
When performing an accurate calculation of heating radiators per area, one cannot do without taking into account the material of the walls and the degree of their thermal insulation. There are also coefficients for this.
Insulation level:
- They take the norm brick walls in two bricks - 1.0.
- Small (absent) - 1.27.
- Good - 0.8.
External walls:
- Not available - no losses, coefficient 1.0.
- 1 wall - 1.1.
- 2 walls - 1.2.
- 3 walls - 1.3.
The level of heat loss is closely related to the presence or absence of a residential attic or second floor. If such a room exists, the coefficient will be reducing 0.7 (for a heated attic - 0.9). As a given, it is assumed that the degree of influence on the room temperature non-residential attic– neutral (coefficient 1.0).
In situations where, when calculating sections of heating radiators by area, one has to deal with a non-standard ceiling height (2.7 m is considered the standard), decreasing or increasing factors are applied. To obtain them, the existing height is divided by the standard 2.7 m. Let's take an example with a ceiling height of 3 m: 3.0 m/2.7 m = 1.1. Next, the indicator obtained when calculating radiator sections by room area is raised to the power of 1.1.
When determining the above norms and coefficients, apartments were taken as a guideline. To find out the level of heat loss in a private house from the roof and basement, another 50% is added to the result. Thus, this coefficient will be equal to 1.5.
Climate
There is also an adjustment for average winter temperatures:
- 10 degrees and above - 0.7
- -15 degrees - 0.9
- -20 degrees - 1.1
- -25 degrees - 1.3
- -30 degrees - 1.5
After making all possible adjustments to the calculation aluminum radiators In terms of area, a more objective result is obtained. However, the above list of factors will not be complete without mentioning the criteria that affect the heating power.
Radiator type
If the heating system is equipped with sectional radiators, in which the axial distance has a height of 50 cm, then calculating the sections of heating radiators will not cause any particular difficulties. As a rule, reputable manufacturers have their own websites indicating the technical data (including thermal power) of all models. Sometimes, instead of power, coolant consumption may be indicated: converting it into power is very simple, because coolant consumption of 1 l/min corresponds to approximately 1 kW. To determine the axial distance, it is necessary to measure the distance between the centers of the supply pipe to the return pipe.
To make the task easier, many sites are equipped with a special calculation program. All that is needed to calculate batteries for a room is to enter its parameters in the specified lines. By pressing the “Enter” field, the number of sections of the selected model is instantly displayed at the output. When deciding on the type of heating device, take into account the difference in the thermal power of the heating radiator by area, depending on the material of manufacture (all other things being equal).
Makes it easier to understand the essence of the issue simplest example calculation of sections bimetallic radiator, where only the area of the room is taken into account. Deciding on the number of bimetallic heating elements with a standard center distance of 50 cm, the starting point is the possibility of heating 1.8 m2 of a home in one section. In this case, for a room of 15 m2 you will need 15: 1.8 = 8.3 pcs. After rounding we get 8 pieces. Batteries made of cast iron and steel are calculated in a similar way.
This will require the following coefficients:
- For bimetallic radiators - 1.8 m2.
- For aluminum - 1.9-2.0 m2.
- For cast iron - 1.4-1.5 m2.
These parameters are suitable for a standard center-to-center distance of 50 cm. Currently, radiators are produced where this distance can range from 20 to 60 cm. There are even so-called “curb” models with a height of less than 20 cm. It is clear that the power of these batteries will be different, which will require making certain adjustments. Sometimes this information is indicated in the accompanying documentation, in other cases you will need to calculate it yourself.
Considering that the heating surface area directly affects the thermal power of the device, it is easy to guess that as the height of the radiator decreases, this figure will fall. Therefore, the correction factor is determined by relating the height of the selected product to the standard of 50 cm.
For example, let's calculate an aluminum radiator. For a room of 15 m2, the calculation of heating radiator sections based on the area of the room gives the result 15:2 = 7.5 pieces. (rounded up to 8 pcs.) It was planned to use small-sized devices with a height of 40 cm. First you need to find the ratio 50:40 = 1.25. After adjusting the number of sections, the result is 8x1.25 = 10 pcs.
Taking into account the heating system mode
The accompanying documentation for the radiator usually contains information about its maximum power. If used high temperature regime operation, then in the supply pipe the coolant heats up to +90 degrees, and in the return pipe - +70 degrees (marked 90/70). The temperature of the home should be +20 degrees. Similar mode of operation modern systems heating is practically not used. Medium (75/65/20) or low (55/45/20) power is more common. This fact requires adjustments to the calculation of the power of heating batteries by area.
To determine the operating mode of the circuit, the temperature difference of the system is taken into account: this is the name for the difference in temperature between the air and the surface of the radiator. The temperature of the heating device is taken as the arithmetic mean between the flow and return values.
For a better understanding, let's calculate cast iron batteries with standard sections of 50 cm in high and low temperature modes. The area of the room is the same - 15 m2. Heating one cast iron section in high temperature mode is provided for 1.5 m2, therefore total number sections will be equal to 15:1.5 = 10. The circuit is planned to use a low-temperature regime.
Determination of the temperature pressure of each mode:
- High temperature - 90/70/20- (90+70):20 =60 degrees;
- Low temperature - 55/45/20 - (55+45):2-20 = 30 degrees.
It turns out that to ensure normal heating of the room in the mode low temperatures the number of radiator sections needs to be doubled. In our case, for a room of 15 m2, 20 sections are needed: this assumes the presence of a fairly wide cast-iron battery. This is why cast iron appliances are not recommended for use in low-temperature systems.
The desired air temperature can also be taken into account. If the goal is to raise it from 20 to 25 degrees, the thermal pressure is calculated with this amendment, calculating the required coefficient. Let's calculate the power of heating batteries based on the area of the same cast-iron radiator, introducing adjustments to the parameters (90/70/25). The calculation of the temperature difference in this situation will look like this: (90+70):2-25=55 degrees. Now we calculate the ratio 60:55 = 1.1. To ensure a temperature of 25 degrees, you need 11 pieces x1.1=12.1 radiators.
Influence of installation type and location
Along with the factors already mentioned, the degree of heat transfer from the heating device also depends on how it was connected. The most effective is considered to be diagonal switching with supply from above, which reduces the level of heat loss to almost zero. The greatest losses of thermal energy are demonstrated by side connection– almost 22%. The remaining types of installation are characterized by average efficiency.
Various blocking elements also help reduce the actual power of the battery: for example, a window sill hanging from above reduces heat transfer by almost 8%. If the radiator is not completely blocked, losses are reduced to 3-5%. Mesh decorative screens partial coverage provoke a drop in heat transfer at the level of the overhanging window sill (7-8%). If the battery is completely covered with such a screen, its efficiency will decrease by 20-25%.
How to calculate the number of radiators for a single-pipe circuit
It should be taken into account that all of the above applies to two-pipe heating circuits, which require the same temperature to be supplied to each radiator. Calculating sections of a heating radiator in a single-pipe system is much more difficult, because each subsequent battery in the direction of movement of the coolant is heated an order of magnitude less. Therefore, the calculation for a single-pipe circuit requires constant revision of the temperature: such a procedure takes a lot of time and effort.
To facilitate the procedure, this technique is used when heating calculations for square meter carried out as for two-pipe system, and then, taking into account the drop in thermal power, sections are increased to increase the heat transfer of the circuit in general. For example, let's take a single-pipe type circuit that has 6 radiators. After determining the number of sections, as for a two-pipe network, we make certain adjustments.
The first of the heating devices in the direction of movement of the coolant is provided with fully heated coolant, so it does not need to be recalculated. The supply temperature to the second device is already lower, so you need to determine the degree of power reduction by increasing the number of sections by the resulting value: 15 kW-3 kW = 12 kW (the percentage of temperature reduction is 20%). So, to replenish heat losses, additional sections will be needed - if at first 8 pieces were needed, then after adding 20% we get the final number - 9 or 10 pieces.
When choosing which way to round, take into account functional purpose room. If we are talking about a bedroom or a nursery, rounding is carried out upward. When calculating the living room or kitchen, it is better to round down. It also has its share of influence on which side the room is located - southern or northern (northern rooms are usually rounded up, and southern ones - down).
This calculation method is not perfect, as it involves enlarging the last radiator on the line to truly gigantic proportions. It should also be understood that the specific heat capacity of the supplied coolant is almost never equal to its power. Because of this, boilers for equipping single-pipe circuits are selected with some reserve. The situation is optimized by the presence of shut-off valves and switching of batteries through a bypass: thanks to this, it is possible to adjust the heat transfer, which somewhat compensates for the decrease in coolant temperature. However, even these techniques do not free you from the need to increase the size of radiators and the number of its sections as you move away from the boiler when using a single-pipe circuit.
To solve the problem of how to calculate heating radiators by area, you won’t need a lot of time and effort. Another thing is to correct the result obtained, taking into account all the characteristics of the home, its size, switching method and location of radiators: this procedure is quite labor-intensive and time-consuming. However, this is exactly how you can get the most accurate parameters for heating system, which will provide warmth and comfort to the premises.
When upgrading a heating system, in addition to replacing pipes, radiators are also replaced. And today they are from different materials, different forms and sizes. What is equally important is that they have different heat output: the amount of heat that can be transferred to the air. And this must be taken into account when calculating radiator sections.
The room will be warm if the amount of heat that escapes is compensated. Therefore, the calculations are based on the heat loss of the premises (they depend on the climate zone, wall material, insulation, window area, etc.). Second parameter - thermal power one section. This is the amount of heat that it can produce at maximum system parameters (90°C at the inlet and 70°C at the outlet). This characteristic must be indicated in the passport and is often present on the packaging.
We calculate the number of sections of heating radiators with our own hands, taking into account the features of the premises and the heating system
One important point: When making calculations yourself, please note that most manufacturers indicate maximum figure, which they obtained under ideal conditions. Therefore, any rounding should be done upward. In the case of low-temperature heating (inlet coolant temperature below 85°C), look for thermal power for the corresponding parameters or make a recalculation (described below).
Calculation by area
This is the most simple technique, which allows you to roughly estimate the number of sections required to heat the room. Based on many calculations, standards for the average heating power of one square area have been derived. To take into account the climatic features of the region, two standards were prescribed in SNiP:
- for regions of central Russia, from 60 W to 100 W are required;
- for areas above 60°, the heating rate per square meter is 150-200 W.
Why are the standards given such a wide range? In order to take into account the wall materials and the degree of insulation. For houses made of concrete, the maximum values are taken; for brick houses, average values can be used. For insulated houses - minimal. Another one important detail: these standards are calculated for medium height ceiling - no higher than 2.7 meters.
Knowing the area of the room, multiply its heat consumption rate, which is most suitable for your conditions. You get the total heat loss of the room. In the technical data for the selected radiator model, find the thermal power of one section. General heat loss divide by power, you get their number. It’s not difficult, but to make it clearer, let’s give an example.
An example of calculating the number of radiator sections by room area
Corner room 16 m 2, in the middle zone, in brick house. Batteries with a thermal power of 140 W will be installed.
For a brick house, we take heat loss in the middle of the range. Since the room is corner, it is better to take a larger value. Let it be 95 W. Then it turns out that heating the room requires 16 m2 * 95 W = 1520 W.
Now we count the number of radiators for heating this room: 1520 W / 140 W = 10.86 pcs. Round up, it turns out to be 11 pieces. This is how many radiator sections will need to be installed.
The calculation of heating radiators per area is simple, but far from ideal: the height of the ceilings is not taken into account at all. For non-standard heights, a different technique is used: by volume.
We count batteries by volume
SNiP also has standards for heating one cubic meter of premises. They are given for different types buildings:
- for brick, 1 m 3 requires 34 W of heat;
- for panel - 41 W
This calculation of radiator sections is similar to the previous one, only now we need not an area, but a different volume and standards. We multiply the volume by the norm, divide the resulting figure by the power of one section of the radiator (aluminum, bimetallic or cast iron).
Formula for calculating the number of sections by volume
Example of calculation by volume
For example, let’s calculate how many sections are needed for a room with an area of 16 m2 and a ceiling height of 3 meters. The building is made of brick. Let's take radiators of the same power: 140 W:
- Finding the volume. 16 m 2 * 3 m = 48 m 3
- We calculate the required amount of heat (the norm for brick buildings 34 W). 48 m 3 * 34 W = 1632 W.
- We determine how many sections are needed. 1632 W / 140 W = 11.66 pcs. Round up, we get 12 pieces.
Now you know two ways to calculate the number of radiators per room.
Heat transfer of one section
Today there is a wide range of radiators. While most are similar in appearance, thermal performance may differ significantly. They depend on the material from which they are made, on the dimensions, wall thickness, internal cross-section and on how well the design is thought out.
Therefore, it is possible to say exactly how many kW in 1 section of an aluminum (cast-iron bimetallic) radiator only in relation to each model. This data is provided by the manufacturer. After all, there is a significant difference in size: some of them are tall and narrow, others are low and deep. The power of a section of the same height from the same manufacturer, but different models, may differ by 15-25 W (see table below STYLE 500 and STYLE PLUS 500). There may be even more noticeable differences between different manufacturers.
However, for a preliminary assessment of how many battery sections are needed for space heating, average thermal power values were calculated for each type of radiator. They can be used for approximate calculations (data are given for batteries with an interaxial distance of 50 cm):
- Bimetallic - one section produces 185 W (0.185 kW).
- Aluminum - 190 W (0.19 kW).
- Cast iron - 120 W (0.120 kW).
More precisely, how many kW can you have in one section of a bimetallic, aluminum or cast iron radiator when you choose a model and decide on the dimensions. The difference in cast iron batteries can be very big. They are available with thin or thick walls, which causes their thermal output to change significantly. Above are the average values for batteries of the usual shape (accordion) and those close to it. Retro-style radiators have significantly lower thermal output.
These are the technical specifications cast iron radiators Turkish company Demir Dokum. The difference is more than significant. She could be even bigger
Based on these values and average standards in SNiP, the average number of radiator sections per 1 m2 was calculated:
- the bimetallic section will heat 1.8 m2;
- aluminum - 1.9-2.0 m2;
- cast iron - 1.4-1.5 m2;
- bimetallic 16 m 2 / 1.8 m 2 = 8.88 pcs, rounded - 9 pcs.
- aluminum 16 m 2 / 2 m 2 = 8 pcs.
- cast iron 16 m 2 / 1.4 m 2 = 11.4 pcs, rounded up - 12 pcs.
These calculations are only approximate. Using them, you can roughly estimate the costs of purchasing heating appliances. You can accurately calculate the number of radiators per room by choosing a model, and then recalculating the number depending on the temperature of the coolant in your system.
Calculation of radiator sections depending on real conditions
Once again, please note that the thermal power of one battery section is indicated for ideal conditions. This is how much heat the battery will produce if its coolant temperature at the inlet is +90°C, at the outlet +70°C, and the room is maintained at +20°C. That is, the temperature pressure of the system (also called “delta system”) will be 70°C. What to do if your system does not exceed +70°C at the inlet? or do you need a room temperature of +23°C? Recalculate the declared power.
To do this, you need to calculate the temperature pressure of your heating system. For example, at your supply you have +70°C, at your outlet +60°C, and in the room you need a temperature of +23°C. Find the delta of your system: this is the arithmetic average of the inlet and outlet temperatures, minus the room temperature.
For our case it turns out: (70°C+ 60°C)/2 - 23°C = 42°C. The delta for such conditions is 42°C. Next, we find this value in the conversion table (located below) and multiply the declared power by this coefficient. Let's learn the power that this section can produce for your conditions.
When recalculating, we proceed in the following order. We find in the columns tinted blue a line with a delta of 42°C. It corresponds to a coefficient of 0.51. Now we calculate the thermal power of 1 radiator section for our case. For example, the declared power is 185 W, applying the found coefficient, we get: 185 W * 0.51 = 94.35 W. Almost twice as much. This is the power that needs to be substituted when calculating the radiator sections. Only taking into account individual parameters the room will be warm.
The calculation of radiators must be done correctly, otherwise a small number of them will not be able to sufficiently warm the room, and a large number, on the contrary, will create uncomfortable living conditions, and you will have to constantly open the windows. Various calculation methods are known. Their choice is influenced by the material of the batteries, climatic conditions, and home furnishings.
Calculation of the number of batteries per 1 sq. m
The area of each room where radiators will be installed can be found in the real estate documents or measured independently. The heat requirement for each room can be found in the building codes, which state that to heat 1m2 in a certain residential area you will need:- for harsh climatic conditions (temperatures below -60 degrees) – 150-200 W;
- for the middle band - 60-100 W.
16 x 100 = 1600 W
The maximum value of power consumption was taken, since the weather is changeable, and it is better to provide a small reserve of power so as not to freeze later in the winter.
Next, the number of battery sections (N) is calculated - the resulting value is divided by the heat generated by one section. It is assumed that one section emits 170 W, based on this, the calculation is carried out:
1600 / 170 = 9,4
It’s better to round up – 10 pieces. But for some rooms it makes more sense to round down, for example, for the kitchen, which has additional heat sources. Then there will be 9 sections.
Calculations can be carried out using another formula, which is similar to the calculations presented above:
N = S/P * 100, where
- N – number of sections;
- S – room area;
- P – heat transfer of one section.
Selecting the exact number of sections of bimetallic batteries
They come in several types, each of them has its own power. The minimum heat generation reaches 120 W, the maximum is 190 W. When calculating the number of sections, you need to take into account the required heat consumption depending on the location of the house, as well as taking into account heat loss:- Drafts that occur due to poorly executed window openings and window profiles, cracks in the walls.
- Waste of heat along the path of the coolant from one battery to another.
- Corner location of the room.
- Number of windows in the room: the more there are, the greater the heat loss.
- Regular ventilation of rooms in winter also affects the number of sections.
Calculation of the number of radiators in a private house
If for apartments it is possible to take the average parameters of heat consumption, since they are designed for standard room dimensions, then in private construction this is incorrect. After all, many owners build their houses with a ceiling height exceeding 2.8 meters, in addition, almost all private premises are corner, so more power will be required to heat them.In this case, calculations based on taking into account the area of the room are not suitable: you need to apply the formula taking into account the volume of the room and make adjustments using coefficients for reducing or increasing heat transfer.
The coefficient values are as follows:
- 0,2 – the resulting final power number is multiplied by this indicator if multi-chamber plastic double-glazed windows are installed in the house.
- 1,15 – if the boiler installed in the house is operating at its capacity limit. In this case, every 10 degrees of heated coolant reduces the power of the radiators by 15%.
- 1,8 – the magnification factor that needs to be applied if the room is corner and has more than one window.
P = V x 41, where
- V – volume of the room;
- 41 – average power required to heat 1 sq. m of a private house.
If you have a room of 20 sq. m (4x5 m – wall length) with a ceiling height of 3 meters, then its volume is easy to calculate:
20 x 3 = 60 W
The resulting value is multiplied by the power accepted by the standards:
60 x 41 = 2460 W - this is how much heat is required to heat the area in question.
Calculation of the number of radiators comes down to the following (taking into account that one radiator section emits on average 160 W, and their exact data depends on the material from which the batteries are made):
2460 / 160 = 15.4 pieces
Let's assume that a total of 16 sections are needed, that is, you need to purchase 4 radiators of 4 sections for each wall or 2 of 8 sections. At the same time, one should not forget about the adjustment coefficients.
Calculation of heat transfer from one aluminum radiator (video)
In the video you will learn how to calculate the heat transfer of one section of an aluminum battery for different parameters of the incoming and outgoing coolant.One section of the aluminum radiator has a power of 199 watts, but this is subject to the declared temperature difference of 70 degrees. will be respected. This means that the coolant temperature at the inlet is 110 degrees, and at the outlet 70 degrees. With such a difference, the room should warm up to 20 degrees. This temperature difference is designated DT.
Some radiator manufacturers provide a heat transfer conversion table and coefficient along with their product. Its value is floating: the higher the temperature of the coolant, the greater the heat transfer rate.
As an example, this parameter can be calculated with the following data:
- The coolant temperature at the radiator inlet is 85 degrees;
- The cooling of water when leaving the radiator is 63 degrees;
- Heating of the room - 23 degrees.
(85 + 63) / 2 – 23 = 52
The resulting number is equal to DT; from the proposed table it can be established that its coefficient is 0.68. Taking this into account, we can determine the heat transfer of one section:
199 x 0.68 = 135 W
Then, knowing the heat loss in each room, you can calculate how many radiator sections are needed for installation in a certain room. Even if, according to calculations, the result is one section, you need to install at least 3, otherwise the entire heating system will look ridiculous and will not warm the area sufficiently.
Calculating the number of radiators is always relevant. To those who build a private house, this is especially important. Apartment owners who want to change radiators should also know how to easily calculate the number of sections on new radiator models.
To make your home warm and cozy, it’s not enough to choose correct batteries— it is necessary to accurately calculate the required number of battery sections in order to warm up the entire room.
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Counting by area
You can approximately calculate the number of sections if you know the area of the room in which the batteries will be installed. This is the most primitive calculation method; it works well for houses where the ceiling height is small (2.4-2.6 m).
The correct performance of radiators is calculated in “thermal power”. According to standards, to heat one “square” of apartment area you need 100 watts - the total area is multiplied by this figure. For example, a room of 25 square meters will require 2500 watts.
Types of sections
The amount of heat calculated in this way is divided by the heat transfer from the battery section (indicated by the manufacturer). When making calculations, the fractional number is rounded up (so that the radiator is guaranteed to cope with warming up). If batteries are chosen for rooms with low heat loss or additional heating devices(for example, for the kitchen), you can round the result down - the lack of power will not be noticeable.
Let's look at an example:
If you plan to install heating radiators with a heat output of 204 W in a room of 25 sq.m., the formula will look like this: 100 W (heating power for 1 sq.m.) * 25 sq.m. ( total area) / 204 W (heat transfer of one radiator section) = 12.25. Rounding the number up, we get 13 - the number of battery sections that will be required to heat the room.
Note!
For a kitchen of the same area, it is enough to take 12 sections of radiators.
Calculation of the number of heating radiator sections video:
Additional factors
The number of radiators per square meter depends on the characteristics of a particular room (availability interior doors, number and tightness of windows) and even on the location of the apartment in the building. A room with a loggia or balcony, especially if they are not glazed, releases heat faster. A room on the corner of a building, where not one but two walls come into contact with the “outside world,” will require more batteries.
The number of battery sections that will be required to heat the room is also affected by the material used to construct the building and the presence of additional insulating cladding on the walls. In addition, rooms with windows facing the courtyard will retain heat better than those with windows facing the street and will require fewer heating elements.
For each rapidly cooling room, the required power, calculated by the area of the room, should be increased by 15-20%. Based on this number, the required number of sections is calculated.
Connection difference
Counting sections by volume
Calculation based on room volume is more accurate than calculation based on area, although general principle remains the same. This scheme also takes into account the height of the ceiling in the house.
According to the standard, 1 cubic meter of space requires 41 watts. For rooms with quality modern finishing, where the windows have double-glazed windows and the walls are treated with insulation, the required value is only 34 W. The volume is calculated by multiplying the area by the ceiling height (in meters).
For example, the volume of a room is 25 square meters with a ceiling height of 2.5 m: 25 * 2.5 = 62.5 cubic meters. A room of the same area, but with 3 m ceilings, will be larger in volume: 25 * 3 = 75 cubic meters.
The number of sections of heating radiators is calculated by dividing the required total power of the radiators by the heat transfer (power) of each section.
For example, let's take a room with old windows with an area of 25 sq.m and with ceilings of 3 m, you need to take 16 sections of batteries: 75 cubic meters (room volume) * 41 W (amount of heat to heat 1 cubic meter of a room where double-glazed windows are not installed) / 204 W (heat transfer from one battery section) = 15.07 (for a residential area, the value is rounded up).
What to consider when calculating?
Manufacturers, when indicating the power of one battery section, are a little disingenuous and inflate the numbers in the expectation that the water temperature in the heating system will be maximum. In fact, in most cases, heating water does not warm up to the calculated value. The passport that comes with the radiators also indicates the minimum heat transfer values. When making calculations, it is better to focus on them, then the house will be guaranteed to be warm.
Note!
Batteries covered with a mesh or screen give off slightly less heat than “open” ones.
The exact amount of heat "lost" depends on the material and design of the screen itself. If you plan to use such a design design, you need to increase the design power of the heating system by 20%. The same applies to batteries located in niches.
Accurate counting of radiators
How to calculate the number of heating radiators for a room in a non-standard room - for example, for a private house? Approximate estimates may not be sufficient. The number of radiators is affected a large number of factors:
- room height;
- total number of windows and their configuration;
- insulation;
- ratio of the total surface area of windows and floors;
- average temperature outside in the cold;
- number of external walls;
- type of room located above the room.
For an accurate calculation, use the formula and correction factors.
Radiator for a large room
Calculation formula
The general formula for calculating the amount of heat that radiators should generate is:
KT = 100 W/sq.m * P * K1 * …* K7
P means the area of the room, CT is the total amount of heat required to maintain a comfortable microclimate. Values from K1 to K7 are correction factors that are selected and applied depending on various conditions. The resulting CT indicator is divided by the heat transfer from the battery segment to calculate the required number of elements (aluminum radiator sections will require a different number than, for example, cast iron ones).
Additional sections
Calculation coefficients
K1 - coefficient for taking into account the type of windows:
- classic “old” windows - 1.27;
- double modern double glazed window - 1.0;
- triple package - 0.85.
K2 - correction for thermal insulation of house walls:
- low - 1.27;
- normal (double row of brick or wall with insulating layer) - 1.0;
- high - 0.85.
K3 is chosen depending on the proportion in which the area of the room and the windows installed in it relate. If the window area is equal to 10% of the floor area, a coefficient of 0.8 is applied. For every additional 10%, 0.1 is added: for a ratio of 20%, the coefficient value will be 0.9, 30% - 1.0, and so on.
K4 - coefficient selected depending on the average temperature outside the window per week minimum temperature in a year. The climate also determines how much heat is needed for the room. At an average temperature of -35, a coefficient of 1.5 is used, at a temperature of -25 - 1.3, then for every 5 degrees the coefficient is reduced by 0.2.
K5 is an indicator for adjusting heat calculations depending on the number of external walls. The basic indicator is 1 (no walls in contact with the “street”). Each outer wall of the room adds 0.1 to the indicator.
K6 - coefficient for taking into account the type of room above the calculated one:
- heated room - 0.8;
- heated attic space — 0,9;
- attic space without heating - 1.
K7 is a coefficient that is taken depending on the height of the room. For a room with a ceiling of 2.5 m, the indicator is 1, every additional 0.5 m of ceilings adds 0.05 to the indicator (3 m - 1.05 and so on).
To simplify calculations, many radiator manufacturers offer an online calculator, which provides Various types batteries and it is possible to configure additional parameters without “manual” calculation and selection of coefficients.
Connecting sections
Calculation depending on the radiator material
Batteries made from different materials give off different quantities heat and heat the room with different efficiency. The higher the heat transfer of the material, the fewer radiator sections will be required to warm the room to a comfortable level.
The most popular are cast iron radiators and bimetallic radiators that replace them. The average heat transfer from a single cast iron battery section is 50-100 W. This is quite a bit, but the number of sections for a room is easiest to calculate “by eye” specifically for cast iron radiators. There should be approximately the same number of “squares” in the room (it is better to take 2-3 more to compensate for the “underheating” of water in the heating system).
The heat output of one element of bimetallic radiators is 150-180 W. This indicator can also be affected by the coating of the batteries (for example, painted oil paint radiators heat the room a little less). The number of sections of bimetallic radiators is calculated according to any of their schemes, with the total amount of heat required divided by the heat transfer value from one segment.
If you want to purchase radiators with installation in Moscow, we recommend contacting
Correct calculation of heating radiator sections is a rather important task for every homeowner. If an insufficient number of sections is used, the room will not warm up during the winter cold, and the purchase and operation of too large radiators will lead to unnecessary high costs for heating.
For standard premises you can use the simplest calculations, but sometimes it becomes necessary to take into account various nuances to get the most accurate result.
To perform calculations you need to know certain parameters
- Dimensions of the room to be heated;
- Type of battery, material of its manufacture;
- The power of each section or one-piece battery, depending on its type;
- Maximum allowed number of sections;
Based on the material they are made of, radiators are divided as follows:
- Steel. These radiators have thin walls and a very elegant design, but they are not popular due to numerous shortcomings. These include low heat capacity, rapid heating and cooling. When hydraulic shocks occur, leaks often occur at the joints, and cheap models quickly rust and do not last long. Usually they are solid, not divided into sections, the power of steel batteries is indicated in the passport.
- Cast iron radiators are familiar to every person since childhood; this is a traditional material from which they are made that are durable and have excellent technical characteristics batteries. Each section of the Soviet-era cast iron accordion produced a heat output of 160 W. This is a prefabricated structure, the number of sections in it is unlimited. There can be both modern and vintage designs. Cast iron retains heat well, is not subject to corrosion or abrasive wear, and is compatible with any coolant.
- Aluminum batteries are lightweight, modern, have high heat transfer, and due to their advantages they are becoming increasingly popular among buyers. The heat output of one section reaches 200 W, and they are also produced in one-piece structures. One of the disadvantages is oxygen corrosion, but this problem is solved using anodic oxidation of the metal.
- Bimetallic radiators consist of internal collectors and an external heat exchanger. The inner part is made of steel, and the outer part is made of aluminum. High heat transfer rates, up to 200 W, are combined with excellent wear resistance. The relative disadvantage of these batteries is high price compared to other types.
Radiator materials differ in their characteristics, which affects calculations
How to calculate the number of heating radiator sections for a room
There are several ways to make calculations, each of which uses certain parameters.
By room area
A preliminary calculation can be made based on the area of the room for which radiators are purchased. This is a very simple calculation and is suitable for rooms with low ceilings (2.40-2.60 m). According to building regulations for heating you will need 100 W of thermal power per square meter of room.
We calculate the amount of heat that will be needed for the entire room. To do this, we multiply the area by 100 W, i.e. for a room of 20 square meters. m, the calculated thermal power will be 2,000 W (20 sq. m * 100 W) or 2 kW.
Correct calculation of heating radiators is necessary to guarantee sufficient heat in the house
This result must be divided by the heat transfer of one section specified by the manufacturer. For example, if it is 170 W, then in our case the required number of radiator sections will be: 2,000 W/170 W = 11.76, i.e. 12, since the result should be rounded to a whole number. Rounding is usually done upward, but for rooms where heat loss is below average, such as the kitchen, you can round down.
It is imperative to take into account possible heat loss depending on the specific situation. Of course, a room with a balcony or located in the corner of a building loses heat faster. In this case, the calculated thermal power for the room should be increased by 20%. It is worth increasing the calculations by approximately 15-20% if you plan to hide the radiators behind the screen or mount them in a niche.
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By volume
More accurate data can be obtained by calculating sections of heating radiators taking into account the height of the ceiling, i.e. by the volume of the room. The principle here is approximately the same as in the previous case. First, the total heat demand is calculated, then the number of radiator sections is calculated.
If the radiator is hidden by a screen, you need to increase the room's need for thermal energy by 15-20%
According to SNIP recommendations for heating each cubic meter residential premises in panel house 41 W of thermal power is required. By multiplying the area of the room by the height of the ceiling, we get the total volume, which we multiply by this standard value. Apartments with modern double-glazed windows and external insulation will require less heat, only 34 W per cubic meter.
For example, let’s calculate the required amount of heat for a room of 20 square meters. m with a ceiling height of 3 meters. The volume of the room will be 60 cubic meters. m (20 sq. m*3 m). The calculated thermal power in this case will be equal to 2,460 W (60 cubic meters * 41 W).
How to calculate the number of heating radiators? To do this, you need to divide the obtained data by the heat transfer of one section indicated by the manufacturer. If we take, as in the previous example, 170 W, then for the room you will need: 2,460 W / 170 W = 14.47, i.e. 15 radiator sections.
Manufacturers tend to indicate overestimated heat transfer rates for their products, assuming that the coolant temperature in the system will be maximum. In real conditions, this requirement is rarely met, so you should focus on the minimum heat transfer rates of one section, which are reflected in the product data sheet. This will make the calculations more realistic and accurate.
If the room is non-standard
Unfortunately, not every apartment can be considered standard. This applies even more to private residential buildings. How to make calculations taking into account the individual conditions of their operation? To do this, you will need to take into account many different factors.
When calculating the number of heating sections, you need to take into account the height of the ceiling, the number and size of windows, the presence of wall insulation, etc.
The peculiarity of this method is that when calculating required quantity heat, a number of coefficients are used that take into account the characteristics of a particular room that can affect its ability to store or release thermal energy.
The formula for calculations looks like this:
KT=100 W/sq. m* P*K1*K2*K3*K4*K5*K6*K7, Where
KT - the amount of heat required for a specific room;
P - room area, sq. m;
K1 - coefficient taking into account the glazing of window openings:
- for windows with conventional double glazing - 1.27;
- for windows with double glazing - 1,0;
- for windows with triple glazing - 0.85.
K2 - coefficient of thermal insulation of walls:
- low degree of thermal insulation - 1.27;
- good thermal insulation (two bricks or a layer of insulation) - 1.0;
- high degree of thermal insulation - 0.85.
K3 - ratio of window area to floor area in the room:
- 50% - 1,2;
- 40% - 1,1;
- 30% - 1,0;
- 20% - 0,9;
- 10% - 0,8.
K4 is a coefficient that allows you to take into account the average air temperature in the coldest week of the year:
- for -35 degrees - 1.5;
- for -25 degrees - 1.3;
- for -20 degrees - 1.1;
- for -15 degrees - 0.9;
- for -10 degrees - 0.7.
K5 - adjusts the heat demand taking into account the number of external walls:
- one wall - 1.1;
- two walls - 1.2;
- three walls - 1.3;
- four walls - 1.4.
K6 - taking into account the type of room located above:
- cold attic - 1.0;
- heated attic - 0.9;
- heated living space - 0.8
K7 - coefficient taking into account the height of ceilings:
- at 2.5 m - 1.0;
- at 3.0 m - 1.05;
- at 3.5 m - 1.1;
- at 4.0 m - 1.15;
- at 4.5 m - 1.2.
All that remains is to divide the obtained result by the heat transfer value of one section of the radiator and round the resulting result to a whole number.
Expert opinion
Victor Kaploukhiy
Thanks to my varied hobbies, I write on various topics, but my favorites are engineering, technology and construction.
When installing new heating radiators, you can focus on how efficient the old system heating. If its work satisfied you, it means that the heat transfer was optimal - these are the data that you should rely on in your calculations. First of all, you need to find on the Internet the value of the thermal efficiency of one section of the radiator that needs to be replaced. By multiplying the found value by the number of cells that made up the used battery, data is obtained on the amount of thermal energy that was sufficient for comfortable living. It is enough to divide the result obtained by the heat transfer of the new section (this information is indicated in the technical data sheet for the product), and you will receive accurate information about how many cells will be needed to install a radiator with the same thermal efficiency indicators. If previously the heating could not cope with heating the room, or, on the contrary, you had to open the windows due to constant heat, then the heat transfer of the new radiator is adjusted by adding or reducing the number of sections.
For example, previously you had a common cast iron battery MS-140 of 8 sections, which pleased with its warmth, but was not aesthetically pleasing. Paying tribute to fashion, you decided to replace it with a branded bimetallic radiator, assembled from separate sections with a heat output of 200 W each. Nameplate power of the used thermal device is 160 W, but over time, deposits have appeared on its walls, which reduce heat transfer by 10-15%. Therefore, the actual heat transfer of one section of the old radiator is about 140 W, and its total thermal power is 140 * 8 = 1120 W. Let's divide this number by the heat transfer of one bimetallic cell and get the number of sections of the new radiator: 1120 / 200 = 5.6 pcs. As you can see for yourself, in order to keep the heat transfer of the system at the same level, a bimetallic radiator of 6 sections will be sufficient.
How to take into account effective power
When determining the parameters of a heating system or its individual circuit, one should not discount one of the most important parameters, namely thermal pressure. It often happens that the calculations are done correctly, and the boiler heats well, but somehow the heat in the house does not work out. One of the reasons for the decrease in thermal efficiency may be the temperature regime of the coolant. The thing is that most manufacturers indicate the power value for a pressure of 60 °C, which occurs in high-temperature systems with a coolant temperature of 80-90 °C. In practice, it often turns out that the temperature in the heating circuits is in the range of 40-70 °C, which means that the temperature difference does not rise above 30-50 °C. For this reason, the heat transfer values obtained in the previous sections should be multiplied by the actual pressure, and then the resulting number divided by the value specified by the manufacturer in the data sheet. Of course, the figure obtained as a result of these calculations will be lower than that obtained when calculating using the above formulas.
It remains to calculate the actual temperature difference. It can be found in tables on the Internet, or calculated independently using the formula ΔT = ½ x (Tn + Tk) – Tvn). In it, Tn is the initial temperature of water at the inlet to the battery, Tk is the final temperature of water at the outlet of the radiator, Twn is the temperature of the external environment. If we substitute into this formula the values Tn = 90 °C (high-temperature heating system mentioned above), Tk = 70 °C and Tvn = 20 °C ( room temperature), then it is not difficult to understand why the manufacturer focuses specifically on this value of thermal pressure. Substituting these numbers into the formula for ΔT, we get the “standard” value of 60 °C.
Taking into account not the nameplate, but the real power thermal equipment, you can calculate the system parameters with permissible error. All that remains to be done is to make an adjustment of 10-15% in case of abnormally low temperatures and provide in the design of the heating system the possibility of manual or automatic adjustment. In the first case, experts recommend installing Ball Valves on the bypass and the coolant supply branch to the radiator, and in the second - install thermostatic heads on the radiators. They will allow you to establish the most comfortable temperature in every room, without releasing heat to the street.
How to correct calculation results
When calculating the number of sections, it is necessary to take into account heat loss. The heat in the house can be quite significant amount through walls and junctions, floors and basements, windows, roofing, natural ventilation systems.
Moreover, you can save money if you insulate the slopes of windows and doors or a loggia by removing 1-2 sections; heated towel rails and a stove in the kitchen also allow you to remove one section of the radiator. Using a fireplace and underfloor heating system, proper insulation of walls and floors will reduce heat loss to a minimum and will also reduce the size of the battery.
Heat loss must be taken into account when calculating
The number of sections may vary depending on the operating mode of the heating system, as well as on the location of the batteries and the connection of the system to the heating circuit.
Used in private homes heating system, this system is more effective than the centralized one, which is used in apartment buildings.
The way radiators are connected also affects heat transfer rates. Diagonal method When water is supplied from above, it is considered the most economical, and the side connection creates losses of 22%.
The number of sections may depend on the mode of the heating system and the method of connecting the radiators
For single-pipe systems, the final result is also subject to correction. If two-pipe radiators receive coolant at the same temperature, then a single-pipe system works differently, and each subsequent section receives cooled water. In this case, first they make a calculation for a two-pipe system, and then increase the number of sections taking into account heat losses.
The calculation diagram for a single-pipe heating system is presented below.
In case of single pipe system successive sections receive cooled water
If we have 15 kW at the input, then 12 kW remains at the output, which means 3 kW is lost.
For a room with six batteries, the loss will average about 20%, which will create the need to add two sections per battery. The last battery in this calculation must be of enormous size; to solve the problem, install shut-off valves and connect through a bypass to regulate heat transfer.
Some manufacturers offer an easier way to get the answer. You can find them on their websites convenient calculator, specifically designed to make these calculations. To use the program, you need to enter the required values in the appropriate fields, after which the exact result will be given. Or you can use a special program.
This calculation of the number of heating radiators includes almost all the nuances and is based on a fairly accurate determination of the room’s need for thermal energy.
Adjustments allow you to save on purchasing extra sections and paying heating bills, and will ensure long years economical and effective work heating systems, and also allow you to create a comfortable and cozy warm atmosphere in a house or apartment.