Calculate heating load: How many kW does your heat pump need?
Undersized means cold days with an expensive immersion heater, oversized means constant cycling and early wear. This calculator gives you the right scale — and shows which cylinders go with it.
Everything at once? The heat pump calculator shows suitability, size, heating costs and federal state public subsidy in three steps.
Your sizing
Standard outside temperature −14 °C
- Total heating load
- 10,4 kW
- Specific
- 90 W/m²
- Buffer cylinder
- 200 l
- Hot water cylinder
- 250 l
Annual heat demand21.000 kWh
Flow temperature on the coldest day45 °C
Expected seasonal performance factor3,5
Heat pump electricity consumption6.000 kWh/year
Rough estimate based on specific heating load. A room-by-room heating load calculation according to ÖNORM EN 12831 by the installer is binding.
Why bigger is not better: An oversized heat pump reaches its target temperature too quickly, switches off, cools down and starts again. This cycling wears out the compressor and lowers the seasonal performance factor. Modulating units cushion this, but they also have a lower modulation limit. If a quote includes significantly more kW than calculated here, ask for the heating load calculation it is based on.