Air source heat pump vs gas boiler: running costs compared

Here is the honest verdict, free of sales spin. At standard 2026 energy prices, electricity costs around four times as much per unit as mains gas, but a good heat pump produces three to four units of heat for each unit of electricity it draws. Those two facts roughly cancel out, so a well-designed heat pump in a reasonably insulated home runs at about the same cost as a modern gas boiler, sometimes a little less. Move to a dedicated heat pump electricity tariff, which offers cheaper off-peak units, and the heat pump usually pulls ahead on cost. The clearest wins come for off-gas-grid homes: against oil or LPG, a heat pump is cheaper to run in nearly every case. A badly designed system running too hot can cost more than gas, which is why design quality and comparing quotes matter so much.

SCOP, the Seasonal Coefficient of Performance, is the most important number on a heat pump quote, because it sets your running cost. It is the average efficiency of the system across a whole year: a SCOP of 3.5 means the heat pump delivers 3.5 units of heat for every unit of electricity it uses, an effective efficiency of 350 percent. Gas boilers, by contrast, top out around 90 percent. The higher the SCOP, the less electricity you buy for the same warmth, so a system designed for a SCOP of 4 will cost noticeably less to run than one stuck at 2.8. SCOP rises when the system runs at low flow temperatures, which is why correctly sized radiators and good insulation pay you back every winter. When comparing installers, ask each one for the predicted SCOP of their design and treat a vague answer as a warning sign.

Upfront cost is where the 7,500 GBP Boiler Upgrade Scheme grant changes everything. Without it, a heat pump costs more to install than a like-for-like gas boiler, and if running costs are merely level, the payback on that gap can stretch over many years. With the grant applied, the net cost of a typical install drops to around 3,500 GBP, which is in the same ballpark as a premium gas boiler replacement. At that point the decision is less about a long payback and more about choosing low-carbon heating for a similar outlay, with running costs that are competitive on gas and cheaper on oil or LPG. For households replacing a boiler that has reached the end of its life anyway, the grant often makes the heat pump the sensible financial choice rather than a costly green upgrade.

For full install pricing, see our Bedford cost guide.

For the many off-gas-grid homes around Bedford, Kettering and Wellingborough, the comparison is not really against mains gas at all, but against oil and LPG. Both are more expensive per unit of heat than gas, and both come with delivery, storage and price volatility. An air source heat pump almost always beats them on running cost, often by a wide margin, and removes the tank and the deliveries entirely. The case gets stronger from 21 July 2026, when the Boiler Upgrade Scheme grant rises to 9,000 GBP for off-gas-grid homes replacing an oil or LPG boiler. For a rural Bedfordshire household currently on oil, switching to a heat pump can mean both lower bills and a much larger grant, which is why off-gas homes tend to see the best overall numbers.

A worked example makes the maths concrete. Take a typical 3-bedroom home that needs about 12,000 kWh of heat a year. The figures below use approximate 2026 unit prices of mains gas at about 6.5p per kWh, electricity at about 24.5p per kWh, heating oil at about 8p per kWh and LPG at about 9.5p per kWh, with the heat pump assumed at a SCOP of 3.5.

These are approximate figures to show the maths; your home, tariff and system design will change them. On these numbers the heat pump beats oil and LPG comfortably and lands close to gas, which is exactly the pattern most reasonably insulated homes see.

The standard electricity rate is not the only price available. Some energy suppliers offer special heat pump or time-of-use electricity tariffs with off-peak rates well below the standard day rate. Running the heat pump and heating your hot water during those cheaper periods, with smart controls handling the timing automatically, can move a heat pump clearly below gas on running cost rather than merely level with it. The saving depends on how much of your heating you can shift into the cheap windows, which is easier with a well-insulated home and a hot water cylinder that holds heat through the day. Tariffs change often and new ones appear regularly, so it is worth comparing suppliers once your heat pump is installed, then reviewing again each year. Picking the right tariff is one of the simplest ways to lower your bills without touching the heating system itself.

Running cost is only half the picture; carbon is the other half. A heat pump is roughly three times more efficient than burning gas, so it cuts the carbon footprint of home heating sharply, by around 70 percent compared with a gas boiler on the current grid. That gap is not fixed: it widens every year as the electricity grid keeps adding renewables, because cleaner electricity makes every unit the heat pump uses lower-carbon. A gas boiler, by contrast, emits the same carbon on its last day as its first. Over the 15 to 20 year lifetime of a heat pump, the direction of travel clearly favours electric heating, both for the climate and for households who expect future policy to keep pushing in that direction. For anyone weighing a long-term decision, the trend matters as much as today's prices, and it points one way.

A fair comparison includes maintenance and lifespan, not just the install price. A heat pump needs one annual service, typically 150 to 300 GBP, and lasts around 15 to 20 years. A gas boiler service is usually cheaper at 80 to 120 GBP, but boilers tend to last only 10 to 15 years, so you are likely to replace a boiler sooner. Factoring in that replacement timing gives a fairer lifetime comparison than the headline install price alone, because a heat pump spreads its higher upfront cost over more years of service. It is the same logic as comparing two cars on total cost of ownership rather than sticker price. When you weigh install cost, running cost, servicing and lifespan together, the gap between a grant-funded heat pump and a new gas boiler narrows further, which is why the lifetime view tends to flatter the heat pump.