HOW TO CHOOSE A HEAT PUMP THAT WILL STILL BE THE RIGHT CHOICE IN 15 YEARS

The key figure is the SCOP, the seasonal coefficient of performance, which tells you how much heat the device returns on average for each unit of electricity across the entire heating season. A good heat pump delivers six or more kilowatt-hours of heat from a single kilowatt-hour of electricity.

This is where the most common trap hides. Many manufacturers put the COP front and centre, but the COP measures efficiency at a single operating point, usually under favourable conditions (7 °C outside, 35 °C flow temperature). The same device may show a COP of around 5 at that point, yet only around 2.5 on a cold winter day with radiators. The COP is a snapshot of the best moment, while the SCOP is the average of the whole season and the only figure from which you can realistically estimate the annual bill. A practical rule: if an offer quotes only the COP and no SCOP anywhere, the missing value is often the answer in itself.

The differences are large in practice. An average air-to-water heat pump reaches a SCOP between 3.5 and 4.5, while top models go above 6. For the comparison to be fair, the SCOP must be measured at the same flow temperature and in the same climate zone, and ideally independently confirmed by the Keymark certificate, which verifies that the value was measured in an accredited laboratory and monitored on every production run, not just on a prototype.

When renovating older houses, the decisive factor is the flow temperature. A device that reaches up to 75 degrees Celsius usually works with the existing radiators, whereas devices with a limit of around 60 degrees often cannot provide enough heat without replacing the radiators.

Noise matters too, and not just the declared figure: the decibel scale is logarithmic, so a difference of seven decibels means not a few percent but roughly five times more sound energy. Choose a device with the lowest possible decibel value, and check the distance at which the noise was measured.

The device will run for two decades or more, so who stands behind it matters. European origin brings a nearby service network and readily available spare parts, whereas with devices from markets such as Asia you risk not finding authorised service when you need it most, and waiting weeks for spare parts, if they are available at all.

How large the differences are in practice was shown by a technical comparison that placed ten leading models in the 12 to 14 kW class under identical conditions (the EN 14825 standard, an electricity price of €0.29 per kilowatt-hour, a 15-year horizon). Among the compared devices, the annual heating cost varied by up to almost 30 percent, which over 15 years amounts to several thousand euros for the same heat and comfort. The highest seasonal efficiency among them was achieved by the European-made KRONOTERM ADAPT M.

*Source: technical comparison of ten leading models (June 2026, publicly available manufacturer data; EN 14825, 22,000 kWh/year, €0.29/kWh). Estimated protection costs are based on average installation costs in Central Europe.

1. Does the device carry the independent Keymark certificate?
2. What is the SCOP, and at which temperature was it measured?
3. What flow temperature does it reach – will it work with the existing radiators?
4. How quietly does it run at part load, not just on paper?
5. Where is the nearest service network, and are spare parts available?