Cooling with the heat pump

Many reversible heat pumps can also cool. Whether that helps in your house depends decisively on the heating surfaces — and here honesty matters more than marketing.

Why radiators barely cool

Cooling through normal radiators barely works: they have too little surface to cool a room noticeably. Worse, a cold radiator surface can drop below the dew point and form condensation (drips, moisture damage).

You can only cool effectively via surfaces with lots of transfer area:

• Underfloor or wall heating (surface heating) — delivers gentle cooling.
• Fan coils (Gebläsekonvektoren) — units with their own fan that actively cool. For radiator houses, the realistic retrofit option.

Dew-point protection is mandatory

Safe cooling needs a dew-point/humidity sensor (e.g. Stiebel's FEK remote) that stops the system before condensation forms. Check whether this sensor is included in the offer.

What fan coils cost (roughly)

Fan coils are more than just the device: add the piping/routing to each unit and a condensate drain (each fan coil produces condensation that must be led away). Budget a noticeable amount per room; the exact figure depends heavily on the routing. Have it itemised per room, including piping and condensate.

The funding question — honestly framed

A common misconception: "activating cooling endangers the funding." The usual position (BEG): the heat pump is funded as a heating replacement; the cooling function is a permitted, sometimes even co-funded, extra — as long as the unit primarily serves as heating and meets the efficiency requirements. Pure/primary cooling is only funded in non-residential buildings. Installers sometimes advise a blanket "don't activate it" — that's over-cautious, not the actual rule.

The safe path if you want to cool later: install the heat pump now as a funded heating replacement, add the cooling components later at your own cost, and keep heating as the primary use.

Important: the exact funding conditions change (2026 BEG reform). Have the funding question confirmed by the energy-efficiency expert who issues your application — they carry responsibility for funding compliance.

In short: cooling via radiators isn't worth it (too little area, condensation risk). Effective only with surface heating or fan coils — plus a dew-point sensor. Funding doesn't ban cooling outright; adding it later at your own cost is the safe route. Have the expert confirm.

That completes the pro stage. Next comes the money and paperwork: funding & execution.