What it costs
Real installed prices for 2026, before and after grant, and the six things that actually move the number on your property.
CostsWhat it costs to run in practice, why flow temperature matters more than the brand on the box, and how it compares against the fuel you are on now.
Tell us about your property and an MCS-certified engineer will be in touch, usually the same working day.
A heat pump's efficiency is its SCOP, the seasonal coefficient of performance. A SCOP of 3.5 means it delivers 3.5 units of heat for every unit of electricity. A gas boiler, at best, gives you about 0.9.
SCOP is not fixed by the model you buy. It is overwhelmingly determined by the flow temperature the system is designed to run at. Drop the flow temperature and the SCOP rises sharply:
| Design flow temperature | Typical SCOP | Effect on your bill |
|---|---|---|
| 35°C | 4.0 – 4.5 | Cheapest to run, needs underfloor or large radiators |
| 45°C | 3.3 – 3.8 | The realistic target for most retrofits |
| 50°C | 2.9 – 3.2 | Workable, noticeably more expensive |
| 55°C+ | 2.4 – 2.8 | Often costs more to run than the boiler it replaced |
This is why an installer's willingness to upsize radiators is not an upsell. It is the difference between a system that saves you money and one that does not.
Take a typical three-bed semi needing roughly 12,000kWh of heat a year including hot water.
| System | Efficiency | Energy bought | Rough annual cost |
|---|---|---|---|
| Heat pump at 45°C | SCOP 3.5 | 3,430 kWh electricity | £850 – £1,000 |
| Heat pump at 55°C | SCOP 2.6 | 4,615 kWh electricity | £1,150 – £1,350 |
| New gas boiler | 90% | 13,330 kWh gas | £800 – £950 |
| Oil boiler | 90% | 13,330 kWh oil | £1,100 – £1,500 |
| LPG boiler | 90% | 13,330 kWh LPG | £1,600 – £2,100 |
| Direct electric | 100% | 12,000 kWh electricity | £3,000 – £3,400 |
These are indicative and move with energy prices, so treat them as ratios rather than promises. The pattern holds regardless of price level: against mains gas a heat pump is roughly line ball, and against oil, LPG and direct electric it wins clearly.
Electricity currently costs roughly three and a half to four times as much as gas per kWh in the UK. A heat pump has to be at least that much more efficient than a boiler simply to break even. At SCOP 3.5 against a 90% boiler it just about is, which is why the honest answer for a mains gas household is parity rather than a dramatic saving.
Two things shift it in the heat pump's favour: a heat pump tariff, which several suppliers now offer at a reduced unit rate for heating, and solar PV, which pairs unusually well because the heat pump multiplies every unit you generate by its SCOP.
If you are on oil, LPG, coal or direct electric heating, the saving is immediate and substantial rather than marginal. That covers a large share of rural Britain, and it is why our regional pages for Norfolk, Suffolk, Dorset, Wiltshire and rural Scotland make a stronger case than the ones for city centres on mains gas.
One thing routinely left out of comparisons: if the heat pump lets you disconnect from gas entirely, you stop paying the gas standing charge, currently around £110 a year. That is a real saving that does not appear in any per-kWh calculation.
For a typical three-bed semi needing about 12,000kWh of heat a year, roughly £850 to £1,000 annually at a well-designed 45°C flow temperature. At a poorly designed 55°C it rises to £1,150 to £1,350. Figures move with energy prices.
Roughly line ball for most mains gas households. Electricity costs around three and a half to four times gas per kWh, so a heat pump has to be that much more efficient just to break even, which at SCOP 3.5 it just about is. A heat pump tariff or solar PV tips it clearly in favour.
Yes, clearly and consistently. Against oil, LPG, coal or direct electric heating the saving is immediate rather than marginal. This is where the strongest financial cases are.
SCOP is the seasonal coefficient of performance: how many units of heat you get per unit of electricity across a whole year. It is driven mainly by design flow temperature, not by the brand. A system at 35°C might achieve 4.0 to 4.5; the same unit at 55°C might manage 2.4 to 2.8.
Yes, substantially, because you are moving your entire heating load onto electricity. Your gas bill should disappear. The comparison that matters is total annual energy cost, not the electricity bill in isolation, and plenty of people get a shock from looking at only one of the two.
Meaningfully. Several suppliers offer tariffs with a reduced unit rate for heat pump households, which closes most of the remaining gap against mains gas. It is worth checking availability before you commit.
Real installed prices for 2026, before and after grant, and the six things that actually move the number on your property.
CostsThe Boiler Upgrade Scheme in England and Wales, Home Energy Scotland north of the border, and what applies in Northern Ireland.
GrantsSurvey, design, grant, installation and commissioning, with honest timescales and a clear account of the disruption.
ProcessWhy sizing comes from a room-by-room heat loss calculation and never from floor area or your old boiler's output.
SizingWhich radiators need upsizing at a lower flow temperature, and why this is the single biggest swing factor in your quote.
RadiatorsWhy heat pumps need a cylinder, what happens if you are on a combi, and how much space you actually need to find.
Hot waterUK coverage
We install air source heat pumps nationwide through MCS-certified regional teams. Grant support differs between England, Wales, Scotland and Northern Ireland, and the regional pages set out what applies where you are.
Get a free, no-obligation quote for heat pump installation in the UK, with the grant deducted so you see the real figure. We come back to you the same working day.