Heat pump running costs, against the boiler you already have
Electricity costs several times what gas costs per unit, and a heat pump delivers several times more heat per unit. Whether you save money is the fight between those two numbers, and it is close enough that how well the system is set up decides it.
The break-even
2.5
The seasonal performance a heat pump has to reach before it costs the same as the boiler it replaced. Above it you save; below it you don't.
- Electricity against gas, per unit
- 3.3×
- Boiler efficiency assumed
- 85%
- Gas standing charge saved
- £108 a year
A year's heating on gas
£865
9,500 kWh of gas, plus the standing charge
On a heat pump at 3.5
£607
£258 less than the boiler, a year
At 2.7
£787
£78 less — the same machine, badly set up
Break-even performance
2.5
Below this a heat pump costs more to run than the boiler
Ofgem's default tariff cap for 1 October 2026 to 31 December 2026, direct debit, GB average, including VAT. The gas figure is Ofgem's own typical domestic consumption value, which covers heating and hot water. The heat pump side drops the gas standing charge, because a house that stops burning gas stops paying it, and both sides leave the electricity standing charge out, because it is the same either way.
The sum
Five lines, and nothing hidden in any of them
A heat pump uses more expensive energy to do the same job with far less of it. Written out, the comparison is short enough that you can check every line of it against your own bill.
| Gas boiler | Heat pump | Why | |
|---|---|---|---|
| Heat the house needs | 8,075 kWh | 8,075 kWh | The same house, the same year, the same temperature |
| Fuel it takes to make it | 9,500 kWh of gas | 2,307 kWh of electricity | A boiler at 85%, a heat pump at 3.5 |
| What that fuel costs | £757 | £607 | 8p a unit against 26.3p |
| Standing charge | £108 | — | The gas meter goes, and so does its standing charge |
| A year | £865 | £607 |
On these figures the heat pump saves £258 a year. Change the seasonal performance and that number moves a long way, which is the next section. Nothing here includes the cost of buying the heat pump: that is on the heat pump guide, with the Boiler Upgrade Scheme grant taken off.
Performance
The same machine, five different answers
Seasonal performance is how many units of heat the system delivers per unit of electricity, averaged over a year. It is not a property of the box on the wall — it is flow temperature, radiator sizing and whether anyone came back to set the controls.
A year's heating at each seasonal performance
Against £865 on the gas boiler it replaced.
- SCOP 2.2£101 more than the boiler£966
- SCOP 2.7£78 less than the boiler£787
- SCOP 3.0£157 less than the boiler£709
- SCOP 3.5£258 less than the boiler£607
- SCOP 4.0£334 less than the boiler£531
The gas line is crossed at 2.5. Below that the heat pump is more expensive to run, whatever else is true about it.
Where the number comes from
We use 2.7 to 3.5 as the honest range for an air source heat pump in a British house. Manufacturers quote higher figures measured at a low flow temperature in a laboratory; what a real system reaches depends on whether the emitters can run at that temperature in January.
This is an assumption, not a published dataset. When metered performance data exists at the scale this site needs, it replaces it.
Flow temperature is the lever
Every 5°C off the flow temperature is worth roughly a tenth of the running cost. That is why a system designed around 55°C flow in radiators sized for a boiler lands at the bottom of the range, and one designed around 40°C in larger emitters lands at the top. The design decision is made before anything is installed.
By region
£56 between the best region and the worst
Ofgem sets the cap by region, and electricity varies across them more than gas does. The same house with the same heat pump at the same performance lands in a different place depending on which network it sits on.
Heat pump against gas boiler, at a SCOP of 3.5
A year's heating, by price cap region. Negative means the heat pump is cheaper.
- Northern£587 against £862£274 less
- Southern£611 against £882£272 less
- London£614 against £884£271 less
- Midlands£591 against £859£268 less
- Yorkshire£591 against £859£268 less
- East Midlands£585 against £851£266 less
- South Wales£613 against £877£265 less
- Southern Western£613 against £878£265 less
- Southern Scotland£602 against £857£255 less
- South East£620 against £871£251 less
- Northern Scotland£608 against £857£249 less
- Eastern£614 against £859£245 less
- North West£611 against £856£245 less
- N Wales and Mersey£643 against £861£218 less
Ofgem's cap regions follow the electricity distribution network areas, not council boundaries. The regional table on the tariff pages maps them.
On a heat pump tariff
The tariff is worth as much as the commissioning
A heat pump runs for hours at a time, which makes it the one appliance in the house that can genuinely be moved into a cheap window. Cosy Octopus prices the day in three bands, and a well-controlled system can put most of its heating into the low ones.
Where these rates come from
- Ofgem — default tariff cap level, by region
- Octopus Energy — published rates for Cosy Octopus
- MHCLG EPC register — running costs recorded on certificates
Last checked against these sources on 17 September 2026.
The price cap
26.3pGB average, direct debit, including VAT
£607 a year to run the heat pump
Cosy Octopus, average
23.6pAveraged across the day over four weeks
£544 a year to run the heat pump£63 less than the cap
Cosy Octopus, cheap windows only
12.9pA bound, not a prediction: no house runs entirely in the windows
£299 a year to run the heat pump£308 less than the cap
Octopus's rates as published on 17 September 2026, averaged over the fourteen regions. The cheap-window row is an upper bound on what a tariff can do, not a forecast: a real house uses the peak band for some of its heating however good the controls are. The electricity guide compares the products in full.
What homes pay now
The certificate's own estimate, by band
Every EPC carries a modelled cost for heating, hot water and lighting, now and with its recommendations done. Averaged over the register, that is the closest thing there is to a published figure for what British homes spend on running themselves.
Modelled running cost by EPC band
England and Wales, each home's latest certificate. Now, and after the certificate's recommendations.
- Now
- After the recommendations
- A£706→£664
- B£503→£472
- C£778→£675
- D£1,084→£795
- E£1,524→£930
- F£2,280→£1,227
- G£3,442→£1,539
The certificate assumes standard occupancy and the fuel prices of the year it was lodged, so these compare bands rather than predict a bill. A heat pump in a band D home will not reach the band B figure without the fabric work that goes with it.
Fabric first, and here is why
A heat pump sized for an uninsulated house is a bigger, more expensive heat pump running at a higher flow temperature, which is the combination that lands at the bottom of the performance range. The insulation is not a nice-to-have before the heat pump; it is what decides which end of this page you end up on.
Average across the register£981£735
Two bands is the usual journey
Homes in the register average £981 a year now and £735 if every recommendation on their certificate were done — a 25% cut, before any tariff change. Which measures move a band takes that apart.
EPC register, England and Wales, certificates to 9 September 2026, each home counted once from its latest certificate.
What goes wrong
Six ways the number on this page becomes the wrong number
Almost every reported case of a heat pump costing more to run than the boiler it replaced is one of these, and five of the six are decided before anything is switched on.
Left on the boiler's settings
The commonest cause of a disappointing heat pump. Installed, set to 55°C flow to make the old radiators work, and never revisited. That single decision is most of the gap between the top and bottom rows on this page.
Sized off a rule of thumb
A room-by-room heat loss calculation is the document that decides your running cost. If a quote arrives without one, it is a quote for a machine rather than a design for a house.
The immersion doing the hot water
A heat pump that hands hot water to the backup immersion heater is running that part of the year at a COP of one. Check what the cylinder is set to do and how often the legionella cycle fires.
A standing charge you forgot to cancel
Keeping the gas meter for a hob costs £108 a year before a single unit is burned. That is a real part of the comparison, and it is easy to leave in place by accident.
Comparing against a new boiler you'd never have bought
These figures assume a working boiler at 85%. If yours is fifteen years old and running at seventy-something, the real comparison is kinder to the heat pump than this page is.
Expecting the tariff to rescue a bad install
A cheap overnight window is worth real money on a system that can pre-heat. On one running flat out at a high flow temperature through the evening peak, a time-of-use tariff costs more than the standard rate.
Questions
Common questions about heat pump running costs
Are heat pumps cheaper to run than gas?
At a seasonal performance of 3.5, yes: £607 a year against £865 on gas, on the current cap. At 2.7 the same house pays £787, which is about the same as the boiler. The machine is identical in both cases; the design and commissioning are not.
What is a SCOP, and what should mine be?
Seasonal coefficient of performance: units of heat delivered per unit of electricity, averaged over a heating season. 2.7 to 3.5 is the honest range for an air source heat pump in a British house. Ask an installer what SCOP their design is expected to reach and at what flow temperature — a quote that cannot answer that is not a design.
Why is electricity so much more expensive than gas?
Per unit, electricity costs about 3.3 times what gas does under the current cap. Policy costs, network charges and the way wholesale electricity is priced against gas all sit in that gap. It is also why a heat pump has to be about three times as efficient as a boiler before it saves anything.
Does a heat pump work in an old house?
Yes, but the running cost depends on how hard it has to work. A solid-walled house with small radiators needs a higher flow temperature, which lowers the seasonal performance and moves the answer on this page towards the expensive end. The insulation work is part of the heat pump decision, not separate from it.
What about the standing charges?
A house that stops burning gas stops paying the gas standing charge, which is £108 a year at the current cap. We count that on the heat pump's side. The electricity standing charge is the same either way, so it is left out of both columns.
Is a special heat pump tariff worth it?
It can be, on a system that can pre-heat. Cosy Octopus prices the day in bands, and shifting heating out of the evening peak is worth real money. On a system running flat out through the peak it is worth less than the standard rate, so the tariff decision comes after the commissioning one.
What one costs to buy, and what the Boiler Upgrade Scheme takes off that, is on the heat pump guide. The rates behind this page are on electricity tariffs and gas tariffs, and the case for replacing like with like is on the boiler guide.
What would it cost in your home?
Enter a postcode and we'll use the cap rates for that region, and what the register says homes like yours spend on heating now.