Calculation based on the dimensions of the room
Another thing is when the installation of the heating system is carried out in a new house. In this case, it is not possible to rely on previous experience in operating heating radiators. It requires a more accurate calculation based on the size of the room.
Such calculations can be made based on:
There are a number of sanitary standards, according to which each square meter area of the room should have a certain power of heating devices. You can easily find these standards on the Internet. So, for the average strip of our country, the power per square meter should be at least 100 watts. On this basis, it is easy to make the necessary calculations.
For example, if we take the area of a room of 12 square meters (three by four), the power of the heaters should be 1200 watts (12 sq.м. 100 W). Divide this value by the power of one section of a bimetallic radiator (200 W at a temperature of the coolant 90 degrees) we have 6 sections.
This calculation can also be considered approximate. A value of 100 watts per square metre can only be calculated if the ceiling is less than 3 metres high. Also this does not take into account the number of windows and other factors.
To get a more accurate calculation, you can use a method that relies on the volume of heated space. In this case the data is also taken from the sanitary standards. For example, for a medium-sized strip per cubic meter you need 41 watts of heating wattage.
If we take the same area as in the example above, then with a ceiling height of 2.7 m we obtain a volume of the entire room of 32.4 cubic metres (20 sq m).м. 2.7 meters ). Then the power of the radiators should be 32,4 41 = 1328,4 W. If we divide by the heat output of one bimetallic section, we obtain 6.64. So, it is desirable to install a 7-section radiator for heating.
As you can see, using the method of calculation according to the volume of the room you can get more accurate data on the number of sections of bimetallic (and any other) heating radiator. But in this case even the presence of windows and some other factors are not taken into account. For clarification you need to use correction factors.
Correct calculation of the number of sections per apartment

Биметаллические радиаторы против алюминиевых | Экспертное мнение
One of the most important issues in providing a comfortable living conditions in a dwelling all year round is a balanced and correctly rated heating system. The standard scheme: a circuit of central heating or stand-alone equipment with radiators, as the main heating devices. Many people when renovating or building a new house superficially treat the organization of heat in the house, choosing simply more massive radiators for larger rooms. However, for a comfortable microclimate and protection from the most serious frosts you need to take into account a lot of parameters, including the heat output of radiators, the area of the room, layout, etc. д. That’s why our customers often ask how many sections of aluminum or bimetallic radiator to put, so that the rooms were really warm and comfortable.
A quick way to calculate the number of sections
Calculation of the number of sections of bimetallic radiators when replacing cast iron batteries with them can be made on the basis of the following considerations:
- Heat output of a bimetal battery is slightly higher than that of a cast-iron battery (at a coolant temperature of 90 ° C, the average values are 200 and 180 W, respectively);
- If the new radiator will warm a little bit better than the old one, that’s not bad at all;
- Over time, the efficiency of the radiators decreases slightly due to clogging of the inner surface by deposits of products of interaction between the metal and the coolant.
Our facts show that the number of sections of a bimetallic radiator should be the same as the previous cast iron radiator. In practice often install one or two more sections to create a reserve for the future, taking into account the last point of the above analysis.
How to calculate the heat output of a bimetallic radiator and one section
The power of a bimetallic radiator is related to its capacity and size. The less medium in the radiator, the more efficient and economical it is. The reason is the small amount of water that is heated faster, so the electricity is spent much less.
Bimetal 500/80 bimetal radiator, heat output. 2280 W, manufacturer. Konner.
Calculating the number of sections
For each room there is a different calculation of the required number of sections. To do this, a number of factors are taken into account: the model of the product, the level of heat dissipation and the area of the room.
The model of the radiator | Heat output (kW) | Room area (with 2.7 m ceiling height) | ||||||||||||||||
8 | 10 | 12 | 14 | 6 | 18 | 20 | 22 | 24 | 26 | 28 | 30 | 32 | 34 | 36 | 38 | 40 | ||
Required number of sections | ||||||||||||||||||
Bimetal 350 | 136 | 7 | 8 | 9 | 0 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 |
Bimetal 500 | 204 | 6 | 7 | 8 | 9 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 |
Glazing and thermal insulation
When making accurate calculations using the formula, allow for corrections for glazing and thermal insulation of the walls. If the object is normally double-glazed, the correction value will be 1.27. For sealed double glazing, K1 is 1.0. If triple insulated glazing is installed, K1 is 0.85. If the number of panes in the glazing unit is increased, the parameter is reduced by 0.25 points.
The thermal insulation of the walls also has a value, it is reflected in the K2 coefficient. With standard insulation, the room is poorly protected from the cold, in this case the parameter is 1.27. Better insulation in the apartment or house allows a ratio of 1.0. If excellent insulation is used, K2 will be 0.85.
Another important point is K3. It reflects the ratio of window area to floor area. Glass is known to let the cold in better than the wall. In apartments and offices with large windows more powerful heating is required. When the window area is about 40% of the floor area, a factor of 1.1 can be used. Further the parameter decreases by 0.1% for every 10% decrease in area.
RS Bimetal heating radiator. Sira Industrie
Rules and ways to determine the optimal number of sections of a bimetallic radiator
The secret of the popularity of bimetallic radiators is that they are not inferior to the traditional cast iron radiators, but they have better technical and operational characteristics. Among the undeniable advantages include:
- High heat transfer coefficient.
- Long service life of more than 20 years.
- Stylish and neat appearance.
- Relatively low weight, which greatly simplifies installation work.
- Availability of nipples that allow connecting sections, so the radiator can be expanded.
The advantage of bimetal
Making the choice in favor of batteries consisting of two metals, apartment owners get a whole set of positive evidence why they do the right thing:
- Long service life, which most manufacturers estimate at 20 years, is a good reason to install bimetallic radiators.
- Power of these products exceeds cast iron, steel and aluminum analogues, allowing their use in systems with unstable pressure.
- Heat output of such a device is almost the same as that of purely aluminum heating batteries.
- Since the coolant is only dealing with steel core, while aluminum is not in contact with it, they are not afraid of corrosion, hence the resulting so long warranty.
Such a disadvantage of bimetallic devices as high cost is lost next to the listed positive technical characteristics that give people a feeling of comfort and safety.
If such designs are supposed to be mounted instead of cast iron, you should make a correct calculation of the number of sections of bimetallic radiators given that they are much better in power and heat output.
Calculation methods
The most popular methods of calculation are made using the actual area and volume of the heated room.
By area
Calculation by area is the easiest, but allows you to determine the number of sections, only in apartments with a height of about 2.5 m. SNIP provides load per meter of 100 watts. This standard for the average strip. In the north beyond latitude 60, it can be significantly higher.
By multiplying the area by 100 you get the power of standardized heat consumption. Dividing it by the heat output of the fin we get the number of fins for heating.
By volume
Calculating by volume is used where the ceilings are higher than 2.6 m. According to the regulations, for heating m.cube. Depending on the type of building required:
Multiplying the area by the height of the room we get the calculated volume in cubes.
How to replace a section of an aluminum radiator
Multiplying the number of cubes by the normative heat consumption of your house we get the power of the normative heat consumption. 2.1.
Calculation of the number of heating radiators
For the climatic zone of Ukraine has long been calculated consumed heat power under standard conditions. Standard conditions include: a room with one window (standard), one door, one exterior wall. For one cubic meter of such living space we take 41 W of heat power. Based on these data it is not difficult to calculate the required number of sections of the radiator, knowing its thermal capacity.
For example, you can take a room of 5 by 6 meters and with a standard ceiling height of 2.7 m. First you need to calculate the volume of the room. So 562,7 = 81 m3. Do not forget that if the front door to the room is in the form of an arch that does not close, the volume of the room oyazazatelno should be added to the volume of the adjacent room. When you know the volume you multiply it by 41 Watts: 81 41 = 3321. The resulting number is the heat energy needed to heat our room.
If you have already decided what radiators you will use and you know their thermal capacity, it is quite simple to calculate the number of sections. You can also start from the desired number of sections by manipulating their heat output. For example let’s take the radiators with thermal efficiency of one section equal to 200 Watt. Divide the capacity of the room by the capacity of the first section: 3321 / 200 = 16.605. The resulting number rounded up to the greater, so for heating our room we need 17 sections of the radiator heating, capacity of 200 watts each. If you have installed cast-iron radiators with interaxial distance of 600 mm, and you are happy with the temperature in the room, but you want to replace them with new radiators you can calculate the required number of sections of new batteries. Heat output of one section of such a cast iron battery is 150 watts. Accordingly multiply 150 by the number of installed in your room sections and we get the number of heat output of heating your room. Proceeding from this number we find the above described way the number of sections of the new radiators.
This simple calculation is based on the condition that the temperature of the coolant is not below 70 C. If the temperature of the heat transfer medium is lower, it is necessary to increase the number of radiator sections. Also, in the calculations, it is necessary to consider the heat loss of the room. Installation of double-glazed windows will reduce heat loss by 15-20%, and installation of a decorative panel covering the radiator will reduce the heat output of the radiator by 20-30%. It is also worth considering the location of your room. corner or not, first or last floor, and the degree of insulation of the walls.