Electric Boiler vs Heat Pump: Which Costs Less to Run?
An electric boiler, an air-to-water heat pump and air conditioning compared on running cost at today’s price cap, on what each needs in your home, and on when each makes sense.
The short answer
- An electric boiler turns each unit of electricity into one unit of heat. That is as good as it gets for anything that heats with an element.
- A heat pump moves heat in from outdoors instead, and delivers about three units of heat for every unit of electricity. On the same tariff it costs roughly a third as much to run.
- There are two kinds. An air-to-water heat pump replaces the boiler and runs your radiators and hot water. Air conditioning is an air-to-air heat pump: it heats, and cools, the rooms it serves, but does not make hot water.
- Arctic AC fits air conditioning. We don’t fit air-to-water systems: for one of those you need a specialist heating installer.
Three ways to heat a home with electricity
Most people searching “electric boiler vs heat pump” live without gas, or are about to leave it, and mean an air-to-water heat pump. That is the fair comparison for a home with radiators. But there is a third option that is worth knowing about, especially in a flat or a home with no radiators at all.
1. Electric boiler
Works like a big kettle: an element heats water, which is pumped round your radiators or underfloor heating, and heats your hot water too. It sits indoors, often in an airing cupboard, with no outdoor unit and no flue. Which? describes them as nearly 100% efficient, and notes they cannot go above 100%. Its output is limited by your home’s electricity supply, so it can struggle in a larger house.
2. Air-to-water heat pump
An outdoor unit gathers heat from the air and puts it into the water in your radiators and a hot water cylinder. It directly replaces a boiler. Because it runs the radiators cooler than a boiler does, some rooms may need larger radiators or new pipework, and a home with a combi boiler usually needs a cylinder fitted. A specialist heating installer fits these.
3. Air conditioning (an air-to-air heat pump)
Modern air conditioning is reversible. In heating mode it is an air-to-air heat pump: the outdoor unit gathers heat and an indoor unit in each room blows it into the room. It needs no radiators, no cylinder and no wet system, and in summer the same units cool the same rooms. It does not heat water, so your hot water stays with an electric boiler, a cylinder or an immersion heater. This is what Arctic AC fits: wall-mounted split, multi-split, ceiling cassette and ducted systems, room by room.
What it costs to run each one
The arithmetic is simple: the heat your home needs, divided by how many units of heat each system gets from a unit of electricity, times the price of a unit. Here are the three numbers we use.
- Price: 26.32p per kWh, the Ofgem price cap electricity rate for 1 October to 31 December 2026, paying by direct debit, as a Great Britain average. The standing charge is left out because you pay it whichever system you choose.
- Heat needed: 9,500 kWh a year for heating and hot water. That is Ofgem’s typical gas use for a medium home from 1 July 2026. Strictly it is gas in, not heat out, so a real home on that bill needs a little less, but it is a fair round figure. The government’s own breakdown puts about four-fifths of home heat into space heating and about a fifth into hot water, so we split it 7,500 kWh and 2,000 kWh.
- Heat per unit of electricity: 1 for an electric boiler. About 2.8 for an air-to-water heat pump: the median measured across a year, hot water included, in the government-funded Electrification of Heat trial, where the middle half of homes saw 2.53 to 3.09. About 3 for air conditioning in heating mode, the figure GOV.UK gives for air-to-air heat pumps.
| System | Electricity a year | At 26.32p per kWh |
|---|---|---|
| Electric boiler: 9,500 ÷ 1 | 9,500 kWh | about £2,500 |
| Air-to-water heat pump: 9,500 ÷ 2.8 | about 3,390 kWh | about £893 |
| Air conditioning for heating (7,500 ÷ 3), electric boiler or immersion for hot water (2,000 ÷ 1) | 2,500 + 2,000 = 4,500 kWh | about £1,184 |
Unit costs only, rounded. Your own figures depend on your home, your tariff and how you use the heating.
Against an electric boiler, the air-to-water heat pump cuts the bill by about two-thirds and the air conditioning route by about half. Across the middle half of the homes in the trial, the air-to-water figure runs from about £809 to about £988 a year. On heating alone the two heat pumps are close; the difference is the hot water, which in the air conditioning row is still heated one-for-one.
Two honest caveats on the air conditioning row. It assumes the indoor units heat the whole home; in practice hallways and bathrooms often keep an electric heater or a towel rail, which costs a little more. And in a colder winter, at 2.5 units of heat rather than 3, the heating share rises from 2,500 to 3,000 kWh, about £1,316 in all.
Off-peak tariffs change the sums for everyone. Electric boilers are often paired with a cheaper night rate and a store of hot water, which narrows the gap. The gap in the units of electricity used does not change.
What happens when it’s freezing?
A heat pump works less efficiently the colder it is outside, because it has further to lift the heat. In the Electrification of Heat trial, the median air-to-water system still delivered 2.44 units of heat per unit of electricity on the coldest day of the monitoring period, when the average outdoor temperature was −0.4 °C. Air conditioning behaves the same way: it keeps heating well below freezing, pauses for a few minutes now and then to defrost its outdoor coil, and still gives more heat per unit than an electric boiler. There is more on that in heating with air conditioning in winter.
An electric boiler is unaffected by the weather, and it is also never better than one-for-one.
What each one needs in your home
| Electric boiler | Air-to-water | Air conditioning | |
|---|---|---|---|
| Heats with | Radiators or underfloor | Radiators or underfloor, some possibly larger | An indoor unit in each room |
| Hot water | Yes | Yes, from a cylinder | No, keep what you have |
| Outdoor unit | No | Yes | Yes |
| Cools in summer | No | Not through radiators | Yes |
Disruption. An electric boiler swap is usually the lightest job: it goes where the old boiler was, though Which? notes a bigger model can need an upgrade to your electricity supply. An air-to-water installation, Which? warns, can take a number of days and be somewhat disruptive, with any radiator, pipework or cylinder changes on top. Air conditioning leaves your plumbing alone: the indoor units go on walls or into ceilings, joined to the outdoor unit by a small pipe run through the wall, and most homes are done in a day or two.
Upfront cost. Which? puts an electric combi boiler at about £1,500 to £2,000 for the boiler itself, with fitting on top. An air-to-water heat pump is a bigger job, and a specialist heating installer will quote for it after a survey. For air conditioning, our price estimator gives you a range for your own rooms in about two minutes.
Which one makes sense for you?
Air conditioning, with your hot water left as it is
- A flat, or any home without radiators, heated today by electric heaters.
- An all-electric home where you would keep the electric boiler or immersion heater for hot water and take the heating load off it in the rooms you use most.
- No space for a hot water cylinder, or no wish to change the radiators.
- You want the same rooms cool in a heatwave.
An air-to-water heat pump
- A house with radiators throughout and room for a cylinder and an outdoor unit.
- You want one system for heating and hot water, replacing the boiler outright.
- You are happy to have a specialist heating installer fit it.
An electric boiler
- A small, well-insulated home that needs little heat.
- No outdoor space for any unit, and radiators you want to keep.
- The lowest upfront cost matters more than the running cost. The Energy Saving Trust sees electric boilers as a second choice where a heat pump is not possible.
The options also combine. Plenty of homes keep an electric boiler for hot water and the odd room, and put air conditioning in the living room and bedrooms, where most of the heat goes. For how the two kinds of heat pump compare in more depth, see air-to-air vs air-to-water; for gas in the mix, the heating comparison; and for the plug-in heater case, air conditioning vs electric heaters. The refrigerant cycle behind every heat pump is explained in how air-to-air heat pumps work.
Frequently asked questions
Is a heat pump cheaper to run than an electric boiler?
Yes, on the same electricity tariff. An electric boiler turns each unit of electricity into one unit of heat. A heat pump moves heat in from outdoors instead: air-to-water systems measured in UK homes delivered about 2.8 units of heat per unit of electricity across a year, and air conditioning in heating mode typically delivers about three. So a heat pump needs roughly a third of the electricity for the same heat, a little more in a cold spell.
Can air conditioning replace an electric boiler?
For heating rooms, often yes: reversible air conditioning is an air-to-air heat pump, and it heats each room it serves for about a third of the electricity of an electric boiler, then cools the same rooms in summer. It does not heat water, so most homes keep the electric boiler or an immersion heater for hot water, and for any room without an indoor unit.
Will a heat pump heat my hot water?
An air-to-water heat pump does, by heating a hot water cylinder, so a home with a combi boiler usually needs a cylinder fitted. An air-to-air heat pump, which is what air conditioning is, does not make hot water at all: that stays with your boiler, cylinder or immersion heater.
Do I need new radiators for a heat pump?
For an air-to-water heat pump, possibly. It runs radiators cooler than a boiler does, so some homes need larger radiators or new pipework in some rooms; a heat loss survey tells you which. Air conditioning does not use radiators at all: each room gets its own indoor unit.
Does Arctic AC fit air-to-water heat pumps?
No. We fit air conditioning: wall-mounted split, multi-split, ceiling cassette and ducted systems, which heat and cool room by room. If you want an air-to-water heat pump to replace your boiler and heat your hot water, you need a specialist heating installer.
See what air conditioning would cost in your home
Two minutes with our estimator gets you a realistic range for your rooms. A free survey turns it into a fixed quote, with no obligation and no hard sell.
Sources
- Ofgem: Energy price cap unit rates and standing charges (1 October to 31 December 2026)
- Ofgem: Energy price cap update from 1 July 2026 (revised typical domestic consumption values)
- Department of Energy and Climate Change: Estimates of heat use in the United Kingdom in 2013 (December 2014)
- Which?: Electric boilers, what you need to know
- Which?: Air source heat pumps explained
- Energy Systems Catapult: Electrification of Heat Demonstration Project, interim heat pump performance data analysis (March 2023)
- GOV.UK: Check if a heat pump is suitable for your home (air-to-air)
- Energy Saving Trust: Electric heating
- Energy Saving Trust: Exploring the role of alternative clean heating solutions
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