That depends on the size of the boat, place of use, period of use and which spaces need to be heated. As a rule of thumb: A heating current of 120 - 200 watts is needed to heat a space of one cubic meter. The volume to be heated should be calculated and the required wattage per cubic meter used. This figure indicates which heater is needed.

Example:
For 33 cubic meters and 125 watts required per cubic meter, 4,125 watts are needed. In this case the Airtronic D4/D4 Plus should be chosen.

When using water heaters, the heating requirement for each room to be heated must be determined, as the output of the convectors or radiators must be selected on this basis.