Electric boiler vs heat pump: which costs less in the UK?

On running cost this is not a close contest. An electric boiler turns one unit of electricity into one unit of heat, so it costs whatever electricity costs: 26.11p per kWh at the Ofgem cap for July to September 2026. A heat pump moves heat instead of making it, so one unit of electricity becomes three or more units of heat, and the same kWh lands at 8.7p. Over a normal heating season that difference is worth well over a thousand pounds.

The reason anyone still buys an electric boiler is that it costs a fraction as much to install and it fits in places a heat pump cannot go. So the real question is not which is cheaper to run, it is whether the install gap ever gets paid back.

The short answer

On running cost this is not a close contest. An electric boiler delivers heat at 26.1p per kWh, a heat pump at SCOP 3.0 delivers it at 8.7p, and an A-rated gas boiler at 8.8p.

The electric boiler wins on install price, £1,500–£3,500 against £8,000–£14,000 before the £7,500 grant, and without that grant it stays cheaper over ten years below roughly 4,700 kWh of annual heat. Buy one when a heat pump will not physically fit, not because it is cheaper to run.

Running cost per kWh of heat

Every figure below is the cost of one kWh of heat delivered into the house, which is the only comparison that means anything. Unit prices are the Ofgem cap for 1 July to 30 September 2026.

Two things fall out of that table. A heat pump at a fairly ordinary SCOP of 3.0 already matches a gas boiler, which is the comparison most people actually care about. And an electric boiler costs three times what a heat pump costs to run, every hour it is on, for as long as you own it.

Ten-year cost at three levels of heat demand

Install costs are the honest ranges rather than a headline price: an electric combi runs £1,500 to £3,500 fitted, and an air source heat pump £8,000 to £14,000 before grant. The table uses the midpoints, £2,500 and £11,000, a heat pump at SCOP 3.2, and ten years of running cost at today's cap.

Ten-year totals, install plus running cost. Electric boiler at 26.11p per kWh; heat pump at 26.11p ÷ 3.2 = 8.2p per kWh of heat. No inflation applied to either, since it affects both.

If you can get the Boiler Upgrade Scheme grant, the heat pump is cheaper over ten years above about 600 kWh of annual heat, which is to say always. Strip the grant out and the crossover moves to roughly 4,700 kWh a year. Below that, the electric boiler's low install cost never gets clawed back within a decade.

When the electric boiler is the right answer

It wins on constraints rather than on cost. The cases that come up repeatedly:

• No outdoor space. A first-floor flat with no balcony, no roof rights and no wall you are allowed to hang a unit on. There is nowhere to put the outdoor unit, so the comparison ends there.
• Listed buildings and conservation areas. An external unit and the pipework through the wall need consent that is often refused. An electric boiler sits inside a cupboard and changes nothing anyone can see.
• Very low heat demand. Under about 4,000 kWh a year, a well-insulated flat may only be paying £1,000 a year to heat. Spending £11,000 to save two thirds of that takes too long if no grant is available.
• You are keeping the radiators. An electric boiler runs at the same flow temperature as the gas boiler it replaces, so the existing radiators still work. A heat pump usually wants larger ones.

Worth knowing on the electrical side: a 12kW electric boiler pulls about 52A on its own, so it wants a dedicated 60A-plus supply and often a consumer unit upgrade. In an older flat on an 60A or 80A main fuse, that is a real constraint and sometimes a supply upgrade from the DNO. Check it before you commit, not after.

When the heat pump is the right answer

Almost everywhere else. If you own a house with somewhere outside for the unit, you qualify for the £7,500 grant in England and Wales, and the arithmetic above is not close. The grant is paid to your installer and comes off the quote, so the number you actually write a cheque for is typically £500 to £6,500 rather than the full install cost.

The two things that decide whether you get a good SCOP or a bad one are radiator sizing and flow temperature. A system designed to run at 45°C with radiators sized for it will hit 3.2 to 3.8. The same heat pump forced up to 55°C because nobody upsized the radiators will sit nearer 2.5, which puts it at 10.4p per kWh of heat and behind gas. The kit is rarely the problem; the design is. Our heat pump running costs guide goes through what a good design looks like.

Installed materials also carry 0% VAT until 31 March 2027, which applies to both options here but is worth more on the larger bill.

What about Economy 7 and storage

An electric boiler on Economy 7 buys electricity at 14.53p overnight instead of 26.11p, but it can only use that rate for heat produced during the window. On its own that is close to useless, because you want heat in the evening. Pair it with a thermal store or a decently sized buffer tank and you can heat water overnight and draw it down through the day, which brings the effective cost of usable heat towards 15 to 17p per kWh once you allow for standing losses.

That is the strongest case an electric boiler has, and it is still roughly double a heat pump at SCOP 3.0. It also costs you the day rate of 31.61p for anything you need outside the window, which in a cold snap is most of it. If you are drawn to this approach because of the cheap night rate, look at storage heater running costs first, since the same logic applies with less plumbing.

Common questions

Is an electric boiler cheaper to run than a heat pump?

No. At the Ofgem Q3 2026 cap an electric boiler costs 26.11p per kWh of heat, because it is roughly 100% efficient and buys electricity at the standard rate. A heat pump running at a seasonal COP of 3.0 delivers the same kWh of heat for 8.7p, and at 3.5 for 7.5p. A gas boiler at 83% efficiency sits at 8.8p. On running cost alone the heat pump is about three times cheaper than the electric boiler.

Why would anyone fit an electric boiler then?

Because it fits where a heat pump does not. An electric boiler is about the size of a kitchen cupboard, needs no outdoor unit, no flue and no gas supply, and it works with your existing radiators at existing flow temperatures. In a flat with no outdoor space, a listed building, or a home with very low heat demand, it is often the only realistic all-electric option.

Does the Boiler Upgrade Scheme cover electric boilers?

No. The £7,500 Boiler Upgrade Scheme grant in England and Wales covers air source and ground source heat pumps, and biomass boilers in some cases. Electric boilers are not eligible. That grant is most of the reason the heat pump wins on ten-year cost even though it costs several times more to install.

Does Economy 7 make an electric boiler competitive?

Only partly, and only with a thermal store. The Economy 7 night rate is 14.53p per kWh against a day rate of 31.61p, so heating water overnight into a cylinder or buffer tank and drawing on it through the day gets the boiler down towards 15p per kWh of usable heat. That is still nearly double a heat pump at SCOP 3.0, and the day rate punishes any heat you need outside the window.

If you are choosing between a heat pump and a gas boiler rather than an electric one, the numbers work differently and the margin is much tighter. That comparison is in heat pump vs gas boiler.