How to choose heat pump capacity
Floor area gives you a first shortlist. To choose precisely you need the building's heat loss and the water temperature your heating system needs.
- What affects the capacity
Insulation, windows, ventilation, ceiling height and the room temperature you want. That is why two houses of the same size can need different capacities. Radiators usually need hotter water than underfloor heating, and with hotter water a heat pump gives less heat and uses more electricity.
- Floor area in the catalogue
For air-to-air units, the catalogue area is for cooling at 100 W per square metre. For air-to-water heat pumps we use 80 W/m² and, where the maker publishes tables, the output at −10 °C and 35 °C water including the electric backup heater. If there is no frost data, we say so. The calculator gives a more precise answer.
dzese.lv · 25 October 2026. This is general guidance. Where it differs from the chosen model manual or the project calculation, follow those.
