Are heat pumps expensive to run?

Ask whether a heat pump is expensive to run and you'll get two confident, opposite answers, both from real households. The difference between them isn't opinion. It's one ratio: how the price of electricity compares with the price of gas or oil, set against how efficiently the heat pump turns that electricity into heat. Once you understand how that ratio works, you can work out roughly where you'd land, without needing this quarter's exact energy prices.

The short answer

A heat pump costs less to run than a gas or oil boiler once its efficiency clears the gap between the electricity price and the fuel price. Most well-installed heat pumps clear that bar comfortably. Badly designed ones, left on the wrong tariff, sometimes don't. The efficiency figure that decides it is called SCOP, and understanding it properly explains almost everything else in this article.

What SCOP actually means

A heat pump doesn't burn fuel to make heat. It moves heat that's already there — in the air, the ground or a body of water — into your home, using electricity to run the pump that does the moving. Our guide to how heat pumps work covers the mechanics in more detail. Because it's moving heat rather than creating it from nothing, it can deliver more energy as heat than it consumes as electricity. That's what the industry calls the Seasonal Coefficient of Performance, or SCOP: a SCOP of 3.5 means that, across a full heating season, a heat pump delivers about three and a half units of heat for every unit of electricity it uses. Well-installed heat pumps in the UK typically land somewhere between 3.5 and 4.0, sometimes higher.

A boiler has a hard ceiling. It burns gas or oil and, at best, turns all of it into heat: 100% efficient, and no more. In a real home, a good gas or oil boiler typically runs at 80% to 95%. An older or poorly maintained one can sit well below that, sometimes 70% or less. That ceiling is the whole reason this comparison isn't a straight fuel swap: a heat pump doesn't have one, in the same sense, which is why it can win on running cost even though electricity itself is the more expensive fuel, unit for unit.

Flow temperature: the dial that moves your SCOP

SCOP isn't fixed to the machine. It's set by how the whole heating system is designed, and the single biggest factor is flow temperature — how hot the water running through your radiators or underfloor pipes needs to be.

A heat pump works harder, and uses more electricity, the bigger the gap it has to close between the outside air and the water in your heating system. Send your radiators water at 35°C instead of 55°C or higher, and the heat pump uses noticeably less electricity to deliver the same warmth. The same machine can perform very differently in two different homes, because it isn't really the heat pump that's efficient or inefficient. It's the system built around it.

Three things get flow temperature right: sizing the radiators or underfloor loops to your home's actual heat loss, rather than matching whatever the old boiler needed; weather compensation, which lowers the flow temperature automatically on milder days instead of running flat out all winter; and commissioning that's genuinely finished, tuned to the property rather than left on a default setting. This is the substance behind "well installed" doing so much of the work in any claim about what a heat pump costs to run, including the one at the end of this article. Our guide to heat pumps in winter covers how this plays out when it's genuinely cold outside.

The tipping point: the ratio that decides it

Strip away the specific prices, and the whole running-cost question comes down to one comparison: the price of a unit of heat from electricity, against the price of a unit of heat from gas or oil.

A unit of heat from a heat pump costs roughly the electricity price divided by its SCOP. A unit of heat from a boiler costs roughly the gas or oil price divided by its efficiency, which sits close to one. Put the two together, and a heat pump wins on running cost once its SCOP is higher than the ratio between the electricity price and the gas or oil price (a little higher, strictly, to allow for the boiler not being 100% efficient either).

To make that concrete with round numbers, not today's prices: at a ratio of roughly 4 to 1 (electricity costing four times as much as gas per unit), a heat pump needs a SCOP above about 4 to come out ahead. At a ratio of 3 to 1, it needs a SCOP above about 3. The lower the ratio, the lower the bar a heat pump has to clear, and the more comfortably a well-installed system clears it.

Where does that ratio actually sit right now? Ofgem's price cap for 1 October to 31 December 2026 puts electricity at around 26.3p per kWh against gas at around 8.0p per kWh, a ratio of roughly 3.3 to 1. That moves every quarter, sometimes sharply, which is exactly why this article argues from the ratio rather than the numbers behind it: check the current cap before you rely on this for a decision.

Two things move that ratio further in a heat pump's favour, and both are within your control. A tariff built for heat pumps, whether a dedicated heat-pump rate or a time-of-use tariff, prices the electricity a heat pump actually uses (steady, long hours, often overnight) lower than a standard flat rate does, which lowers the effective ratio it has to beat. And leaving the gas network altogether drops its daily standing charge out of the comparison completely, typically somewhere around 30p a day whatever you burn, which shifts the whole-bill comparison further still, on top of any change to the per-unit maths.

A battery adds a second lever

A heat pump uses a lot of electricity, steadily, across long hours — exactly the kind of demand a home battery is built to serve. Charge the battery when electricity is cheap, overnight or whenever a time-of-use tariff dips, and run the heat pump from it later, and you're buying less electricity at the expensive rate. It's a saving on what you buy, not a way of earning money from what you generate. See where a battery fits in for how that works alongside a heat pump.

So is a heat pump expensive to run?

Put those pieces together and the conclusion holds generally: a well-installed heat pump system should cost less to run than the boiler it replaces, because its SCOP typically clears the price ratio it needs to beat by a comfortable margin. Add a time-of-use tariff, a battery, or both, and that gap should widen further, since each one lowers the effective price of the electricity a heat pump uses. Get the installation wrong — undersized radiators, no weather compensation, a system running hotter than it needs to — and the SCOP falls, the margin narrows, and on a standard tariff it can vanish altogether.

That's the whole case in one line. Well installed beats a boiler on running costs alone. Add a smarter tariff or a battery, and it should beat it by a good deal more.

One more thing worth keeping separate: none of this is about what a heat pump costs to install, which is its own question, and rarely a like-for-like swap for a boiler; it usually comes with a hot water cylinder, and often new radiators or pipework too. See what a heat pump costs to install for that side of the sums.

See what it would cost in your home

Every ratio above is generic. Your home's actual figure depends on your current tariff, your boiler's real efficiency, and how your system would be designed. The instant estimate takes about three minutes, needs no survey and no commitment, and gives you an approximate installation figure to start from.

Get your instant estimate, or read our full comparison of a heat pump and a gas boiler for the wider decision.

Frequently asked questions

Isn't electricity more expensive than gas, so how can a heat pump be cheaper to run?
Yes, a unit of electricity costs more than a unit of gas, typically two to four times as much depending on the current price cap. A heat pump doesn't burn a unit of electricity to make a unit of heat, though: it moves several units of heat for every unit it uses. Once its SCOP clears that price gap, it comes out cheaper per unit of heat, even though the electricity itself costs more.

What SCOP do I need for a heat pump to beat my boiler?
Roughly whatever the current ratio is between the electricity price and the gas or oil price. If electricity costs three times as much as gas per unit, you need a SCOP above about 3. If it costs four times as much, you need a SCOP above about 4. Well-installed systems in the UK typically reach 3.5 to 4.0, which clears most realistic ratios.

Does flow temperature really matter that much?
It's the single biggest lever on SCOP. A lower flow temperature, achieved through correct radiator sizing, weather compensation and proper commissioning, means the heat pump does less work for the same warmth. The same machine, badly set up, can run at a meaningfully lower SCOP in the same house.

Do I need a special tariff for a heat pump to save money?
Not to make it run, but it changes the maths in your favour. A tariff designed for a heat pump, or a time-of-use tariff, prices its typical usage pattern (steady, long hours, often overnight) lower than a standard flat rate, which lowers the ratio your heat pump has to beat.

Does a battery help lower running costs further?
Yes, by letting you buy less electricity at the expensive rate. Charge it when electricity is cheap and draw on it later, including to run the heat pump, and you reduce how much you buy at peak prices. See where a battery fits in for the fuller picture.