Air-to-air heat pump vs electric radiators: running costs compared

Quick answer: At the October 2026 cap rate of 26.32p/kWh, an air-to-air heat pump delivers a kilowatt-hour of heat for about 7.5p. An electric radiator charges the full 26.32p. Heat one room most days all winter and the heat pump could save around £560 a year, against £1,200 to £2,000 to install.

This one comes up for extensions, garden offices, flats with no gas supply and that one stubbornly cold room. Both options run on electricity. What separates them is what they do with it.

Why one kilowatt-hour costs 7.5p and the other 26p

An electric radiator is 100% efficient. Every unit of electricity becomes exactly one unit of heat. No more, no less. That sounds good until you meet a heat pump.

An air-to-air unit is the same hardware as air conditioning: a box outside, a wall-mounted unit inside, and a refrigerant loop moving heat from the outdoor air into the room. Across a heating season, air-to-air systems typically manage a SCOP of 3.0 to 4.0 (Axiom Eco Homes, citing the MCS product database, checked July 2026). Take 3.5 as a working figure and the effective price of heat falls from 26.32p to about 7.5p per kilowatt-hour at the current Ofgem cap.

That’s the whole argument. Everything after this is detail.

What that looks like over a year

Say your living room needs 3,000kWh of heat a year, a fair estimate for a well-used room in an average semi. Here’s what that heat costs from each system at the current cap rate, with two smaller rooms for scale.

These are estimates at a single price point, and your tariff, room and habits will move them. Our running cost calculator does the sums with your own numbers.

Install costs point the other way

A 1.5kW Creda wall-mounted panel heater is £139 at Screwfix (checked July 2026). A plug-in oil-filled radiator costs less again, and neither needs a tradesperson unless you want it hard-wired.

A single-room 2.5kW air-to-air split runs £1,200 to £2,000 installed, and a whole-home multi-split £2,500 to £4,500 (Axiom Eco Homes, checked July 2026). The Boiler Upgrade Scheme pays £2,500 towards air-to-air heat pumps (gov.uk); eligibility rules apply, so have an MCS installer confirm your job qualifies before you count on it.

We haven’t tested any of these units. Prices and performance figures are from published listings and spec sheets, checked July 2026.

Now run the payback. A £1,600 single split saving £564 a year clears itself in three winters, faster again if the £2,500 grant applies. The spare room is another story: £94 a year against £1,600 is seventeen years, around the outer edge of the kit’s life. For that room, the £139 panel heater is the right answer.

What the maths leaves out

The heat pump brings cooling in summer, which no radiator can match, and it filters and dehumidifies while it runs. On the other side of the ledger: the outdoor unit needs wall or ground space, makes some noise, and consent rules apply in flats and conservation areas.

It also won’t touch your hot water or your existing radiators. If you want a system that does, that’s an air-to-water machine, a different animal we compare in our air-to-water vs air-to-air guide.

Electric radiators keep two quiet advantages: silence and zero maintenance. If the room currently has storage heaters, our storage heaters vs heat pumps comparison covers that upgrade path, and panel-heating options get the same treatment in infrared vs heat pumps.

Tariffs move the totals, not the winner

Everything above uses the single-rate cap. Smart tariffs shift the totals. An air-to-air unit can pre-warm a room during a cheap overnight or afternoon window, and at 10p/kWh its delivered heat costs under 3p per kilowatt-hour. An electric radiator on the same tariff still pays the full evening rate for every hour you actually want warmth.

And if the cap falls next quarter? Both bills drop together. The ratio between them is set by the SCOP, not by the price, so the heat pump keeps its three-to-one lead on any tariff. Cheaper electricity narrows the cash gap and stretches the payback a little. It never closes it.

Our verdict

Daily-use rooms belong to the heat pump. At cap rates it produces heat at roughly a third of the price, and over a decade that dwarfs the install cost. Occasional rooms belong to the cheap radiator, and pretending otherwise wastes capital. If whole-house heating is the real question, start with our heat pump guide: the air-to-water route qualifies for the larger £7,500 grant.

FAQs

Can an air-to-air heat pump heat a whole flat?

Yes, with a multi-split: several indoor units run off one outdoor box, typically £2,500 to £4,500 installed. You still need a separate plan for hot water, usually an immersion heater or a hot water heat pump.

Are expensive “eco” electric radiators more efficient?

No. Every direct electric heater is 100% efficient, from a £600 designer radiator to a £139 panel. Better thermostats and timers can trim waste, but the price per unit of heat is identical. Physics does not read brochures.

Is there a grant for either option?

Air-to-air heat pumps can claim £2,500 through the Boiler Upgrade Scheme; air-to-water systems get £7,500. Electric radiators get nothing.