How to calculate the power of a gas heating boiler - an example of calculation + formulas

Autonomous heating for a private house is convenient, affordable and very diverse. Any owner of a private house willingly buys a gas boiler and installs everything necessary so that he no longer depends on the vagaries of the weather or the surprises associated with the operation of centralized heating systems.

However, it is important to choose the right equipment. If its capacity exceeds the real needs of the building for heat, part of the cost of heating will simply be thrown into the wind. A device with low productivity will not be able to provide the house with enough heat. Therefore, still at the design stage autonomous heating system you need to find the answer to the question: how to calculate the power of a gas boiler?

What values ​​are used in the calculations?

The simplest calculation of the boiler power by area looks like this: you need to take 1 kW of power for every 10 square meters. m. However, it is worth considering that these standards were drawn up even under the Soviet Union. They do not take into account modern building technologies, in addition, they may turn out to be insolvent in an area whose climate differs markedly from the conditions of Moscow and the Moscow region. Such calculations can be suitable for a small building with an insulated attic, low ceilings, excellent thermal insulation, windows in which double-glazed windows are inserted, etc. Alas, only a few buildings meet these requirements. To make a more detailed calculation of the boiler power, you need to consider a number of factors, such as:

• climatic conditions in the region;
• dimensions of the premises;
• the degree of insulation of the house;
• possible heat loss of the building;
• the amount of heat required to heat the water.

In addition, in houses with forced ventilation, the calculation of the boiler for heating should take into account the amount of energy needed to heat the air. As a rule, it is necessary to use special software for calculations:

When calculating the capacity of a gas boiler, another 20% should be added in case of unforeseen situations, such as severe cooling or a decrease in gas pressure in the system.

When designing a heating system, it is necessary to calculate not only the power of the boiler, but also the number of sections of radiators. You can find out more about this in our material:https://aquatech.tomathouse.com/en/otoplenie/raschety/raschet-kolichestva-sektsiy-radiatorov-otopleniya.html.

Should I buy a too powerful boiler?

Modern heating equipment is equipped with automatic systems that allow you to adjust the gas flow. This is very convenient because it eliminates unnecessary expenses. It may seem that an accurate calculation of the power of the heating boiler is not so important, because you can just buy a boiler with high power rates. But it’s not so simple.

The correct selection of heating equipment will extend its life

Unreasonable excess of the thermal capacity of the equipment can lead to:

• increase costs for the acquisition of system elements;
• decrease in boiler efficiency;
• failures in the operation of automatic equipment;
• rapid wear of components;
• condensation in the chimney, etc.

Thus, you need to try to "get" exactly in the power that suits your home.

Baxi gas boilers have established themselves as reliable heating equipment. Overview of the model range with the characteristics and features in our next material:https://aquatech.tomathouse.com/en/otoplenie/kotly/gazovyiy-kotel-baxi.html.

Gas boiler for houses of standard configuration

It is not too difficult to calculate the capacity of a gas boiler for houses created according to a standard project. In such buildings, the ceiling height does not exceed three meters. To do this, use the formula: MK = S * UMK / 10where

• MK is the estimated boiler power in kW;
• S is the total area of ​​the premises in sq.m;
• UMK - the specific power of the boiler, which should be for every 10 square meters. m

The last indicator is set depending on the climatic zone and is:

• 0.7-0.9 kW for the southern regions;
• 1.0-1.2 kW for the middle strip;
• 1.2-1.5 kW for the Moscow region;
• 1.5-2.0 for the northern regions.

According to this formula, the estimated boiler capacity for a house of 200 square meters. m., which is located in the middle lane, will be: 200X1.1 / 10 = 22 kW. Please note that this formula shows how to calculate the power of the boiler, which is used only for heating the house. If you plan to use a dual-circuit system that provides for heating water for domestic purposes, you should increase the capacity of the equipment by another 25%.

How to take into account the height of the ceilings in the calculations?

Since many private houses are being built according to individual projects, the methods for calculating the boiler power given above will not work. To make a sufficiently accurate calculation of a gas heating boiler, you must use the formula: MK = QT * Kzapwhere:

• MK - design power of the boiler, kW;
• Qt - predicted heat loss of the structure, kW;
• Kzap is the safety factor, which is 1.15 to 1.2, i.e. .15-20%, by which experts recommend increasing the design capacity of the boiler.

The main indicator in this formula is the predicted heat loss of the structure. To find out their size, you need to use another formula: Qt = V * PT * k / 860where:

• V - volume of the room, cubic meter .;
• Pt is the difference between external and internal temperatures in degrees Celsius;
• k is the dispersion coefficient, which depends on the thermal insulation of the building.

The dispersion coefficient varies depending on the type of building:

• For buildings without thermal insulation, which are simple structures made of wood or corrugated iron, the dispersion coefficient is 3.0-4.0.
• For structures with low thermal insulation, typical for buildings with single brickwork with ordinary windows and a roof, the dispersion coefficient is assumed to be 2.0-2.9.
• For houses with an average level of thermal insulation, for example, buildings with double brickwork, a standard roof and a small number of windows, a dispersion coefficient of 1.0-1.9 is taken.
• For buildings with increased thermal insulation, a well-insulated floor, roof, walls and windows with double-glazed windows, a dispersion coefficient of 0.6-0.9 is used.

For small buildings with good thermal insulation, the estimated power of the heating equipment can be very small. It may happen that the market simply does not have a suitable gas boiler with the necessary characteristics. In this case, you should purchase equipment whose capacity will be slightly higher than the calculated. Automatic heating control systems help smooth out the difference.

Some manufacturers have taken care of the convenience of customers and have placed special services on their Internet resources that make it possible to calculate the necessary boiler capacity without any problems. To do this, you need to enter data such as:

• temperature that must be maintained indoors;
• average temperature for the coldest week of the year;
• the need for hot water;
• presence or absence of forced ventilation;
• number of floors in the house;
• ceiling height;
• information about the overlap;
• information about the thickness of the outer walls and the materials from which they are made;
• information about the length of each wall;
• information about the number of windows;
• description of the type of windows: number of cameras, glass thickness, etc.
• the size of each window.

After all the fields are filled in, it will be possible to find out the design capacity of the boiler. Options for detailed calculations of the power of boilers of various types are graphically presented in the table:

Some options have already been calculated in this table, you can use them as correct in advance (click on the picture to enlarge)

Our calculator for quick calculation

To calculate the thermal power of the heating boiler in this calculator, it is enough to enter the area of ​​the heated room, select the necessary parameters and click the “Calculate” button.

Quite simple options for how to calculate the capacity of a heating boiler were given above. It should be remembered that for structures of a more complex structure, these methods may be unsuitable if:

• the building has rooms with different ceiling heights;
• planned floor heating;
• the construction of facilities that require additional heat consumption (pool, greenhouse, sauna, etc.) is being planned.

You may also find useful material on the principles of calculating gas flow for heating:https://aquatech.tomathouse.com/en/gazosnabzhenie/kak-rasschitat-rashod-gaza.html.

These points should be taken into account at the design stage. The most accurate calculation of the power of heating equipment can be calculated by heating engineers. All necessary calculations can be carried out at the design stage of the room.