Heat pump in a 1980s house
Built with cavity insulation and reasonable loft levels from new. Middle of the road — not a problem house, not a new build.
With the radiators as they are
Saves £69
a year · existing radiators, average size
With upgraded radiators
Saves £198
a year · SCOP 3.4
What to do first
Often a straightforward heat pump candidate with modest radiator upgrades. Check the radiators before assuming.
Upgrading the radiators is worth about £129 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 11,500 kWh a year.
- That is roughly 9,775 kWh of actual heat, once boiler losses are taken off.
- A heat pump on the existing radiators would use about 3,371 kWh of electricity to deliver it.
- Break-even electricity price: 28.15p 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.