Heat pump in a flat
Low heat demand because neighbours heat three or four of your surfaces for you. The obstacle is rarely the sums — it is where the outdoor unit goes and what the lease says.
With the radiators as they are
Saves £85
a year · existing radiators, average size
With upgraded radiators
Saves £158
a year · SCOP 3.4
What to do first
Check the lease and freeholder position before spending money on a survey. Air-to-air or a high-temperature unit may be the only practical options.
Upgrading the radiators is worth about £73 a year in this house — which is the difference between a heat pump being a good idea and a questionable one.
The numbers behind that
- Typical gas use for this kind of house: about 6,500 kWh a year.
- That is roughly 5,525 kWh of actual heat, once boiler losses are taken off.
- A heat pump on the existing radiators would use about 1,905 kWh of electricity to deliver it.
- Break-even electricity price: 30.57p per kWh. The cap is currently 26.11p.
If your break-even price is above the price you actually pay, the heat pump wins. If it is below, it does not — and no amount of enthusiasm changes that arithmetic. A dedicated heat pump tariff can move your real price down enough to flip it.