Solid fuel boilers are an effective solution for heating residential and commercial premises. They can not only heat houses, but also heat water for domestic needs. In this article, you will learn how to correctly calculate the power of a double-circuit solid fuel boiler for heating and hot water supply, as well as the principles of its operation.
How to calculate the power of a double-circuit solid fuel boiler for heating
To select the boiler capacity, it is necessary to take into account several factors:
- Room area (S).
- Ceiling height .
- Thermal insulation level of the building .
- Climate of the region .
General formula for calculating boiler power:
P = (S × k) / 10Where:
- P — is the required boiler power (in kilowatts).
- S — is the total area of the heated room (in square meters).
- k — thermal insulation coefficient (depends on the condition of the house).
Thermal insulation coefficients:
- 0.6–0.9 — for well-insulated houses (with modern windows, insulated walls).
- 1.0–1.9 — for houses with average insulation.
- 2.0 and above — for poorly insulated buildings (old houses, poor windows and walls).
Example: For a house of 100 m² with good thermal insulation (k = 0.8):
P = (100 × 0.8) / 10 = 8 кВтThus, a boiler with a capacity of 8 kW will be sufficient for heating this house.
How to calculate the capacity of a boiler for heating water (DHW)
If you plan to use the boiler for heating hot water, the boiler capacity should be increased. It is recommended to add about 20-30% to the calculated heating capacity to provide the required amount of hot water for a family of 3-4 people.
Calculation example:
If the estimated heating power is 8 kW and you plan to use hot water:
P_general = 8 кВт × 1.3 = 10.4 кВтThus, a boiler with a capacity of 10-11 kW is suitable for heating a house and providing hot water.
How a solid fuel boiler heats water for domestic needs
Solid fuel boilers can be equipped with an additional heat exchanger (or indirect heating boiler), which is connected to the hot water supply system (DHW). The water heating process occurs as follows:
- The fuel is burned in the combustion chamber, releasing heat.
- Heat is transferred to the coolant (most often this is water).
- The hot coolant circulates through the radiators, heating the room.
- In boilers with a DHW function, part of the heat is used to heat water in an additional circuit (heat exchanger).
- Heated water is supplied to taps for domestic use (bathroom, kitchen).
Thus, a solid fuel boiler can perform two tasks at once: heat the house and provide hot water.
Solid fuel boiler: heating and water heating