The short version
- A heat pump's efficiency depends heavily on flow temperature
- Electricity costs more per unit than gas, so efficiency has to make up the gap
- Good insulation and correct emitter sizing decide the outcome
- A badly designed heat pump can cost more to run than the boiler it replaced
The mechanics of the comparison
A modern condensing gas boiler is roughly 90 percent efficient. A heat pump moves heat rather than making it, so it can deliver several units of heat per unit of electricity — but only if it's running at a low flow temperature into adequately sized emitters. Push the flow temperature up to compensate for undersized radiators and the efficiency falls fast.
What tips it either way
These are the levers that actually decide your bill.
- Design flow temperature — the single biggest factor
- Insulation level and airtightness
- Radiator or underfloor capacity in each room
- Electricity tariff, including any heat pump specific rates
- How the household uses heating — steady running suits heat pumps
Our position
We won't promise savings we can't calculate. At survey we produce heat loss figures and a design flow temperature, and from that you can see the realistic picture for your specific house rather than a national average.
Common questions
Will a heat pump definitely cut my bills?+
Not automatically. It depends on design, insulation and tariff — we'd rather model it than promise it.
Do heat pumps work in cold weather?+
Yes, they operate below freezing, though efficiency reduces as outside temperatures drop.
Is a hybrid system worth considering?+
It can be in harder-to-treat homes. It changes the grant position, so we'd discuss it at survey.
What about servicing costs?+
Heat pumps need annual maintenance too, including the cylinder's safety components.
Want the numbers for your house?
Book a survey and we'll model your actual heat loss.