Costs and running · 7 min read
Air Conditioning vs Gas Central Heating: Running Cost Compared
Gas is cheaper per unit. Heat pumps deliver several units of heat per unit of energy. Which wins depends on how many rooms you are heating.
Published 2026-07-20 · Updated 2026-07-20 · WDI Group (Surrey) Ltd
Start with the unit rates
Gas costs materially less per kilowatt hour than electricity in the UK. If both appliances turned one unit of energy into one unit of heat, gas would win every time and there would be nothing to discuss.
They do not. A gas boiler is at best a little over 90% efficient. An air-to-air heat pump commonly returns 300–400% because it is moving heat, not making it.
Where the crossover sits
Once you apply those efficiencies, the two technologies land close together on cost per unit of delivered heat, with the heat pump often ahead on milder days when it runs at its most efficient.
The decisive factor is usually not the tariff, it is coverage. Heating one room with a heat pump beats heating a whole house with a boiler to warm the same one room.
Shoulder season is the heat pump's home ground
In October, and again in March, most households want warmth in the living room in the evening and nothing else. An air conditioning unit delivers that in minutes at low output and low cost, without bringing a hot water cylinder and eleven radiators along for the ride.
Many customers tell us the first winter changes how they use their central heating rather than replacing it.
We do not claim it replaces your boiler
An air-to-air system heats air in the rooms where units are installed. It does not heat your hot water, and it does not warm rooms with no unit in them. On the coldest days a whole-house system still has a job to do.
Treat it as targeted heating and cooling that reduces how hard the rest of the house has to work, not as a like-for-like boiler swap.
Frequently asked questions
- Will it cut my gas bill?
- Most customers see reduced gas use in spring and autumn, when they heat one or two rooms with the heat pump rather than firing the boiler for the whole property.
- Does it work when it is freezing outside?
- Yes. Modern units produce useful heat well below zero, though efficiency falls as outdoor temperature drops.