How to calculate the power of a heating boiler

The right choice of boiler power is the key to a comfortable atmosphere in the house. With insufficient power in frosts, the house will be cold, with excess power, heating costs will increase due to a decrease in boiler efficiency. How to perform a calculation taking into account all the features of your home – in this article

Approximate calculation
To roughly estimate the required power of the boiler, you can use a simplified formula, based on the fact that heating 10 m 2 of a room requires an average of 1 kW of thermal energy. Accordingly, it is enough to divide the area of ​​\u200b\u200bthe dwelling by 10 – you get the approximate required boiler power in kW. It is recommended to add a power margin of 15-20%, so the final formula looks like this:

So, for heating a house with a total area of ​​100 m 2 , a boiler with a capacity of approximately 12 kW is required.

But keep in mind that this is a very approximate calculation, suitable only for a preliminary estimate. To accurately determine the required power, a calculation of the heat loss of the building is required. It is not so easy to do this, and it is simply not always possible – for example, if the house is not yet completed. In this case, you can use the calculation by area, taking into account the most significant features of the climate and the building.

Room-by-room calculation taking into account climatic features
Calculate the required power for each room on the same floor. To do this, multiply the area of ​​\u200b\u200bthe room by the specific heating power.

If the ceiling height in any room is more than 3 m, multiply the required power by h / 3.
Add up the power requirements for all rooms on the same floor. If another heated floor is located below, multiply the resulting number by 0.85. If the basement is heated – by 0.95. If the top floor is a heated floor, multiply by another 0.85.
Calculate the required power for all floors and add up.
Multiply the resulting power by the insulation coefficient:
0.7-0.9 – for buildings with increased thermal insulation: two-brick walls plus additional thermal insulation, double-glazed windows, well-insulated roof and floor.
1.0-1.5 – for buildings with standard thermal insulation: double brick, standard roof insulation.
2-3 – for buildings with increased heat transfer: single-brick walls, increased glazing, single-glazed windows.
3-4 – for non-insulated buildings made of corrugated iron, one layer of boards or OSB, etc.

Multiply the required power by the coefficient of the climatic zone:
0.7-0.9 – for the southern regions of Russia
1.0-1.5 – for the middle lane
1.5-2.0 – for the north
If you are going to use the boiler not only for heating, but also for hot water, multiply the result by 1.3.
Now pick up a boiler with a power not lower than the value obtained.
Take into account the efficiency of the boiler. So, if the efficiency of the selected boiler is 90%, multiply the calculated power by 1.1. Check if the boiler output is sufficient, taking into account the last adjustment. For electric boilers, this item can be omitted, their efficiency is close to 100%.
Calculation example
Let the house have two floors without a heated basement, on each floor – two corner rooms of 16 m 2 with two windows, two corner rooms of 14 m 2 with one window, one inner room of 8 m 2 with one window and one inner room without windows with an area of ​​10 m 2 . Ceiling height 3.3 m. Standard insulation, double-glazed windows, solid glazing and panoramic windows. Region – Moscow region.