The boiler size needed depends on the construction of the house, the size and type of heating system, the geographical location of the house and the amount of radiation in an existing structure.
The way to determine what your actual requirement is to have a heat load done on your home by a qualified heating technician. This calculation looks at the size of the structure, insulation, doors and windows along with your climate area for outdoor design temperature.
The heat output of a boiler is measured in Kilowatts. The output you require depends on the size of the room to be heated. To calculate the output you require, follow the instructions below:
Multiply Room Length x Room Width x Room Height (measure in metres if possible). (If your measurements are in feet and inches multiply the figure by 0.028368 to convert to metres.) Help

70W/m3 heat load requirement at older construction of the house and 40W/m3 heat load requirement at new construction of the house. (in Central Europe).You will need approximately 5kW(15,000 Btu's) output to run sanitary hot water.

The smallest CARBOROBOT is the C30 BIO . It can heat about max. 600 m3 (app. 200m2 area).
For the larger buildings up to 800m3(app. 300m2 area) the C40 BIO and Farmer F40 boilers are good.
Heat several apartment building + swimming pool or workshop, glasshouse, possible with Farmer F60 and C80 types.

As a very general guide an average 3 bedroom house is likely to require a boiler output somewhere in the region of 15 kW. to 25kW. or 50,000 to 85,000 BTU's, with 75% needed for central heating and 25% for hot water.

The Carborobot and Farmer types are automatic working boilers, in residental house mode they can operate several days without supervision.

The CARBOROBOT 30 BIO is new production. C30 BIO can be perfectly employed for the heating of privat hauses, blocks of freehold flats, workshops, garden greenhouses, plant-houses, in every place, where a continuous, regulated, automatic heating without control is necessary.

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The CARBOROBOT 40 is in production more than 25 year. C40BIO can be perfectly employed for the heating of privat hauses, blocks of freehold flats, workshops, garden greenhouses, plant-houses, in every place, where a continuous, regulated, automatic heating without control is necessary. CARBOROBOT totally replaces oil and gas boilers with similar capacity.

CARBOROBOT Farmer is a model typically designed for use in country areas. They are suitable for burning wood pellets and wood logs.

The CARBOROBOT boilers can make sanitary hot water(SHW) simultaneously with the heating. For this we offer hot exchanger and recomendations