Are air source heat pumps worth it?

Heat pumps attract more confident nonsense than anything else we install. One side says they do not work in British winters. The other says every home should have one tomorrow. Neither is true.

We fit them, so read this knowing that. What follows is what we would tell a neighbour — including the four situations where our answer is "not yet".

What a heat pump actually does

It moves heat rather than making it. A refrigerant circuit pulls warmth out of the outside air — which holds usable heat well below freezing — and concentrates it to a temperature that will heat your home and your water.

Because it moves heat that already exists rather than burning something, it delivers more energy as heat than it uses as electricity. That is the whole idea, and it is why comparing one to an electric heater is misleading.

The difference nobody explains: low and slow

This is the single most useful thing to understand, and most disappointment traces back to it.

A gas boiler makes water very hot and heats your rooms in short bursts. A heat pump makes water gently warm and keeps it circulating. The house sits at a steady temperature instead of swinging up and down.

Three consequences follow, and they are the ones that catch people out:

• Radiators may need to be bigger. Lower water temperature means more surface area is needed to deliver the same warmth. Some homes need none changed; some need several enlarged.
• You stop turning the heating off. Letting the house go cold and reheating it works against how a heat pump operates.
• Insulation matters more. Gentle heat cannot outrun a house that loses it quickly.

Which homes suit one

• Reasonably insulated homes — loft and cavity insulation done, or worth doing first.
• Homes off the gas grid, currently on oil or LPG. This is often the clearest case of all.
• Homes with somewhere for a cylinder. An airing cupboard or utility space.
• Homes with outside space for the unit, away from bedroom windows.
• Anyone replacing a boiler anyway — the comparison is fairest at that moment.

When we say not yet

Four honest cases:

• The house is poorly insulated. Do that first. It is cheaper, it makes the heat pump smaller, and doing it the other way round produces an expensive disappointment.
• There is genuinely nowhere for a cylinder. Common in flats and in homes converted to a combi boiler years ago.
• The only place for the outdoor unit is against a neighbour's wall or under a bedroom window.
• The boiler is two years old and working. There is no urgency, and waiting costs nothing.

None of these are permanent. They are reasons to do something else first.

What moves the price

We are not going to print a number here, because a heat pump quote swings more on the individual house than almost anything else we fit. What actually moves it:

• Heat loss — how much warmth your home leaks decides the size of unit, and size drives cost more than anything.
• Radiators — how many, if any, need enlarging.
• Hot water cylinder — whether you have one already or need one fitted.
• Pipework — existing runs are sometimes fine and sometimes not.
• Siting — how far the outdoor unit sits from the plant space.

A proper survey produces a heat loss calculation for your actual house. Anyone quoting a heat pump without one is guessing, and an undersized system is the most expensive mistake available.

Heat pumps and solar together

A heat pump raises your electricity use, which changes the sums on solar considerably — a bigger array often makes sense where it would not have before. The two work together well, with one honest caveat: your heat pump works hardest in winter, when solar produces least.

We have set that out properly in our solar and heat pumps guide, including what a battery does and does not solve.

What to ask any installer

• Will you do a room-by-room heat loss calculation? The correct answer is yes, before quoting.
• Which radiators need changing, and is that in the price?
• Where exactly will the outdoor unit and the cylinder go?
• Are you MCS certified? Ask for the number.
• Will your own team install it, or a subcontractor?

Our guide to choosing an installer covers those checks in full — they apply to heat pumps as much as to solar.

So — worth it?

If your home is reasonably insulated, you have space for a cylinder, and you are replacing a boiler anyway — yes, and it is a straightforward decision.

If your loft is bare or there is nowhere for a cylinder, not yet. Fix that first and the answer changes.

We are MCS-certified, we use our own installers rather than subcontractors, and we will tell you if your home is not ready. Our heat pump page sets out how we work.

Published 25 August 2026 by ECONEXIS, MCS-certified installers based in Chadwell Heath, Essex.