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How To Calculate The Power Of A Boiler For Heating A House - Gas, Electric, Solid Fuel
How To Calculate The Power Of A Boiler For Heating A House - Gas, Electric, Solid Fuel

Video: How To Calculate The Power Of A Boiler For Heating A House - Gas, Electric, Solid Fuel

Video: Multi-Fuel Boilers Residential Heating Systems - How to Calculate BTU Heat Requirement for Your Home 2022, December

Heating boiler power: meaning and calculation

boilers power calculation
boilers power calculation

The main characteristic taken into account when buying heating boilers, both gas and electric or solid fuel, is their power. Therefore, many consumers who are going to purchase a heat generator for a room heating system are concerned about how to calculate the boiler power based on the area of ​​the premises and other data. This is what the next lines are about.


  • 1 Calculation parameters. Things to Consider
  • 2 Gas boilers
  • 3 How to calculate the power for electric boilers
  • 4 For solid fuel
  • 5 Over and under

Calculation parameters. What to consider

But first, let's figure out what this so important value is in general, and most importantly, why it is so important.

In essence, the described characteristic of a heat generator operating on any type of fuel shows its performance - that is, how much area the room can be heated together with the heating circuit.

For example, a heating device with a power of 3 - 5 kW is able, as a rule, to "cover" a one-room or even a two-room apartment with heat, as well as a house with an area of ​​up to 50 square meters. m. Installation with a value of 7 - 10 kW "pull" for three-room housing with an area of ​​up to 100 square meters. m.

In other words, they usually take a power equal to about a tenth of the entire heated area (in kW). But this is only in the most general case. To obtain a specific value, a calculation is needed. Various factors must be taken into account in the calculations. Let's list them:

  • Total heated area.
  • The region where the calculated heating is in effect.
  • House walls, their thermal insulation.
  • Heat loss of the roof.
  • Boiler fuel type.

And now let's directly talk about the calculation of power in relation to different types of boilers: gas, electric and solid fuel.

Gas boilers

Based on the foregoing, the power of boiler equipment for heating is calculated using one fairly simple formula:

Boiler N = S x N beats / ten.

Here the values ​​of quantities are deciphered as follows:

  • Boiler N - power of this particular unit;
  • S is the total sum of the areas of all rooms heated by the system;
  • N beats - the specific value of the heat generator required for heating 10 sq. m. area of ​​the room.

One of the main determining factors for the calculation is the climatic zone, the region where this equipment is used. That is, the calculation of the power of a solid fuel boiler is carried out with reference to specific climatic conditions.

In this case, you need to take the following values ​​of N beats.

  • N beats = 1.7 - 1.8 kW per 10 sq. meters of area - for the regions of the North and Siberia.
  • N beats = 1.3 - 1.5 kW per 10 sq. meters of area - for areas of the middle lane.
  • N beats = 0.7 - 0.8 kW per 10 sq. meters of area - for the southern regions.

    Solid fuel boiler Kupper
    Solid fuel boiler Kupper

For example, let's calculate the power of a solid fuel heating boiler relative to the Siberian region, where winter frosts sometimes reach -35 degrees Celsius. Take N beats. = 1.8 kW. Then for heating a house with a total area of ​​100 sq. m. you will need an installation with a characteristic of the following calculated value:

Boiler N = 100 sq. m x 1.8 / 10 = 18 kW.

As you can see, the approximate ratio of the number of kilowatts to the area of ​​one to ten is not valid here.

However, taking into account the climatic component for calculating the power characteristics of a heat generator is in some cases insufficient. It must be remembered that heat losses may occur due to the specific design of the premises. First of all, you need to consider what the walls of the dwelling are. How insulated the house is - this factor is of great importance. It is also important to consider the structure of the roof.

In general, you can use a special coefficient by which you need to multiply the power obtained according to our formula.

This coefficient has the following approximate values:

  • K = 1, if the house is more than 15 years old, and the walls are made of bricks, foam blocks or wood, and the walls are insulated;
  • K = 1.5, if the walls are not insulated;
  • K = 1.8, if, in addition to non-insulated walls, the house has a bad roof that allows heat to pass through;
  • K = 0.6 for a modern house with insulation.

Suppose, in our case, the house is 20 years old, built of bricks and well insulated. Then the power calculated in our example remains the same:

Boiler N = 18x1 = 18 kW.

If the boiler is installed in an apartment, then a similar coefficient must be taken into account here. But for an ordinary apartment, if it is not on the first or last floor, K will be 0.7. If the apartment is on the first or last floor, then K = 1.1 should be taken.

Next, let's move on to considering the case with a different type of fuel.

How to calculate the power for electric boilers

Electric boiler in the bathroom
Electric boiler in the bathroom

Electric boilers are rarely used for heating. The main reason is that electricity is too expensive today, and the maximum capacity of such installations is not high. In addition, interruptions and long-term power outages in the network are possible.

The calculation here can be done using the same formula:

Boiler N = S x N beats / ten, after which the resulting indicator should be multiplied by the necessary coefficients, we have already written about them.

However, there is another, more accurate in this case, method. Let's indicate it.

This method is based on the fact that the value is initially taken to be 40 W. This value means that so much power without taking into account additional factors is needed to warm up 1 m3. Further, the calculation is carried out as follows. Since windows and doors are sources of heat loss, it is necessary to add 100 W to each window, and 200 W to the door.

At the last stage, the same coefficients are taken into account, which were already mentioned above.

For example, let us calculate in this way the power of an electric boiler installed in a house of 80 m2 with a ceiling height of 3 m, with five windows and one door.

Boiler N = 40x80x3 + 500 + 200 = 10300 W, or approximately 10 kW.

If the calculation is carried out for an apartment on the third floor, it is necessary to multiply the resulting value, as already mentioned, by a reduction factor. Then N boiler = 10x0.7 = 7 kW.

Now let's talk about solid fuel boilers.

For solid fuel

This type of equipment, as the name implies, is distinguished by the use of solid fuel for heating. The advantages of such units are obvious for the most part in remote villages and summer cottages where there are no gas pipelines. Firewood or pellets - pressed shavings - are usually used as solid fuel.

The method for calculating the power of solid fuel boilers is identical to the above method, which is typical for gas heating boilers. In other words, the calculation is carried out according to the formula:

Boiler N = S x N beats / ten.

After calculating the strength index according to this formula, it is also multiplied by the above coefficients.

However, in this case, it is necessary to take into account the fact that a solid fuel boiler has a low efficiency. Therefore, after calculating by the described method, a power reserve of about 20% should be added. However, if it is planned to use a heat accumulator in the heating system in the form of a container for accumulating the coolant, then the calculated value can be left.

solid fuel boiler drawing
solid fuel boiler drawing

Drawing of a solid fuel boiler rated power


Finally, we note that installing a boiler for heating without first calculating its power can lead to two undesirable situations:

  1. Boiler power is lower than required for heating existing premises.
  2. Boiler power is higher than required to heat existing premises.

In the first case, in addition to the fact that the house will be constantly cold, the unit itself may fail due to constant overloads. And the fuel consumption will be unreasonably high. Reinstalling a boiler for a new one is associated with large material costs and difficulties in dismantling, is it worth talking about moral costs? That is why it is so important to correctly calculate the power of the unit!

In the second case, not everything is so deplorable. The overpowering of the boiler is mostly just inconvenient. Firstly, this is the feeling of unnecessarily spent money on an expensive unit. Secondly, oddly enough, a too powerful unit that constantly works half-heartedly reduces its efficiency and wears out quickly. Plus, a lot of fuel will be wasted.

As you can see, in the second case, there are also significant disadvantages. However, here the situation can be corrected if, say, adding the function of heating hot water supply to the boiler. In any case, the final decision is up to the consumer.

So, we looked at ways to calculate the power of a heating boiler. These recommendations should help consumers during the complex process of choosing and purchasing a heating unit.

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