Calculation of boiler power for houses and apartments: two methods

The basis of any heating system is the boiler. Whether it will be warm in the house depends on how correctly its parameters are selected. And in order for the parameters to be correct, it is necessary to calculate the power of the boiler. These are not the most complex calculations – at the level of the third grade, you will only need a calculator and some data on your possessions. Handle everything yourself, with your own hands.

General moments

In order for the house to be warm, the heating system must make up for all the existing heat losses in full. Heat escapes through walls, windows, floor, roof. That is, when calculating the power of the boiler, it is necessary to take into account the degree of insulation of all these parts of an apartment or house. With a serious approach, specialists are ordered to calculate the heat loss of the building, and according to the results, the boiler and all other parameters of the heating system are already selected. This task is not to say that it is very difficult, but it is required to take into account what the walls, floor, ceiling are made of, their thickness and degree of insulation. They also take into account what windows and doors cost, whether there is a supply ventilation system and what is its performance. In general, a long process.

There is a second way to determine heat loss. You can actually determine the amount of heat that a house / room loses with the help of a thermal imager. This is a small device that displays the actual picture of heat loss on the screen. At the same time, you can see where the outflow of heat is greater and take measures to eliminate leaks.

Now about whether it is worth taking a boiler with a power reserve. In general, the constant operation of the equipment on the verge of capabilities negatively affects its service life. Therefore, it is desirable to have a margin of performance. Small, about 15-20% of the calculated value. It is quite enough to ensure that the equipment does not work at the limit of its capabilities.

Too much stock is unprofitable economically: the more powerful the equipment, the more expensive it is. And the price difference is significant. So, if you are not considering the possibility of increasing the heated area, you should not take a boiler with a large power reserve.

Calculation of boiler power by area

This is the easiest way to choose a heating boiler by power. When analyzing many ready-made calculations, an average figure was derived: heating 10 square meters of area requires 1 kW of heat. This pattern is valid for rooms with a ceiling height of 2,5-2,7 m and medium insulation. If your house or apartment fits these parameters, knowing the area of ​​uXNUMXbuXNUMXbyour house, you can easily determine the approximate performance of the boiler.

To make it clearer, we present an example of calculating the power of a heating boiler by area. There is a one-story house 12 * 14 m. We find its area. To do this, we multiply its length and width: 12 m * 14 m = 168 sq.m. According to the method, we divide the area by 10 and get the required number of kilowatts: 168/10 = 16,8 kW. For ease of use, the figure can be rounded off: the required power of the heating boiler is 17 kW.

Accounting for ceiling heights

But in private homes, ceilings can be higher. If the difference is only 10-15 cm, it can be ignored, but if the ceiling height is more than 2,9 m, you will have to recalculate. To do this, it finds a correction factor (by dividing the actual height by the standard 2,6 m) and multiplies the figure found by it.

Ceiling Height Adjustment Example. The building has a ceiling height of 3,2 meters. It is required to recalculate the power of the heating boiler for these conditions (the parameters of the house are the same as in the first example):

• We calculate the coefficient. 3,2 m / 2,6 m = 1,23.
• We correct the result: 17 kW * 1,23 u20,91d XNUMX kW.
• We round up, we get 21 kW required for heating.
  

As you can see, the difference is quite significant. If it is not taken into account, there is no guarantee that the house will be warm even at average winter temperatures, and there is no need to talk about severe frosts.

Accounting for the region of residence

Another thing to consider is the location. After all, it is clear that much less heat is required in the south than in the Middle Strip, and for those who live in the north, the “Moscow Region” power will obviously be insufficient. To account for the region of residence, there are also coefficients. They are given with a certain range, since within the same zone the climate still changes a lot. If the house is located closer to the southern border, a smaller coefficient is applied, closer to the north – a larger one. It is also worth considering the presence / absence of strong winds and choose a coefficient taking them into account.

• The central strip of Russia is taken as a standard. Here the coefficient is 1-1,1 (closer to the northern border of the region, it is still worth increasing the boiler capacity).
• For Moscow and the Moscow region, the result obtained must be multiplied by 1,2 – 1,5.
• For the northern regions, when calculating the boiler power by area, the figure found is multiplied by 1,5-2,0.
• For the southern part of the region, the reduction coefficients are: 0,7-0,9.
  

An example of adjustment by zones. Let the house for which we are calculating the power of the boiler be located in the north of the Moscow region. Then the found figure of 21 kW is multiplied by 1,5. Total we get: 21 kW * 1,5 = 31,5 kW.

As you can see, when compared with the original figure obtained when calculating the area (17 kW), obtained as a result of using only two coefficients, it differs significantly. Almost twice. So these parameters must be taken into account.

Power of a double-circuit boiler

Above we talked about calculating the power of the boiler, which works only for heating. If you plan to also heat the water, you need to increase the productivity even more. In calculating the power of the boiler with the possibility of heating water for domestic needs, 20-25% of the reserve is included (multiply by 1,2-1,25).

Example: we adjust for the possibility of hot water supply. The found figure of 31,5 kW is multiplied by 1,2 and we get 37,8 kW. The difference is solid. Please note that the reserve for water heating is taken after the location is taken into account in the calculations – the water temperature also depends on the location.

Features of calculating the performance of the boiler for apartments

The calculation of the boiler power for heating apartments is calculated according to the same norm: 10 kW of heat per 1 square meters. But the correction is going on in other ways. The first thing that needs to be taken into account is the presence or absence of an unheated room above and below.

• if another heated apartment is located below / above, a coefficient of 0,7 is applied;
• if there is an unheated room below / above, we do not make any changes;
• heated basement / attic – coefficient 0,9.

It is also worth considering the number of walls facing the street when calculating. Corner apartments require more heat:

• in the presence of one external wall – 1,1;
• two walls face the street – 1,2;
• three outer – 1,3.

These are the main areas through which heat escapes. It is imperative to take them into account. You can also take into account the quality of the windows. If these are double-glazed windows, adjustments can not be made. If there are old wooden windows, the figure found must be multiplied by 1,2.

You can also take into account such factors as the location of the apartment. In the same way, you need to increase the power if you want to buy a double-circuit boiler (for heating hot water).

Volume calculation

In the case of determining the power of a heating boiler for an apartment, you can use a different method, which is based on the norms of SNiP. They prescribe the norms for heating buildings:

• heating one cubic meter in a panel house requires 41 W of heat;
• to compensate for heat loss in brick – 34 watts.

To use this method, you need to know the total volume of the premises. In principle, this approach is more correct, since it immediately takes into account the height of the ceilings. A little difficulty may arise here: usually we know the area of ​​uXNUMXbuXNUMXbyour apartment. The volume will have to be calculated. To do this, multiply the total heated area by the height of the ceilings. We get the desired volume.

An example of calculating the power of a boiler for heating an apartment. Let the apartment be on the third floor of a five-story brick building. Its total area is 87 sq. m, ceiling height 2,8 m.

1. Finding volume. 87 * 2,7 = 234,9 cu. m.
2. Rounding up – 235 cu. m.
3. We consider the required power: 235 cubic meters. m * 34 W = 7990 W or 7,99 kW.
4. We round up, we get 8 kW.
5. Since there are heated apartments above and below, we apply a coefficient of 0,7. 8 kW * 0,7 = 5,6 kW.
6. Rounding up: 6 kW.
7. The boiler will also heat domestic water. We will give a margin of 25% for this. 6 kW * 1,25 = 7,5 kW.
8. The windows in the apartment have not been changed, they are old, wooden. Therefore, we use a multiplying factor of 1,2: 7,5 kW * 1,2 = 9 kW.
9. Two walls in the apartment are external, so once again we multiply the figure found by 1,2: 9 kW * 1,2 = 10,8 kW.
10. Rounding up: 11 kW.

In general, here is the method for you. In principle, it can also be used to calculate the power of a boiler for a brick house. For other types of building materials, the norms are not prescribed, and a panel private house is a rarity.