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How much does a heat pump cost to run?

There’s no single number for what a heat pump costs to run — it depends far more on your home and your tariff than on the pump itself. Here’s what really moves the cost, so you can work out whether one would suit you.

• Efficiency is the whole game. A heat pump doesn’t make heat, it moves it — so for each unit of electricity it delivers several units of heat. How many depends on the weather and how the system’s set up (installers call this the COP or seasonal efficiency). The higher it runs, the less electricity each unit of warmth costs you.
• Your tariff does the heavy lifting. A heat pump runs on electricity, which per unit costs more than gas — so the deal you’re on matters enormously. A time-of-use or dedicated heat-pump tariff, where you warm the home in cheaper windows, can change the sums completely. Is a time-of-use tariff worth it? →
• A warm, well-insulated home costs less to heat. This is true of any heating, but heat pumps reward it more: they work best delivering steady, gentle heat, which a draughty, poorly-insulated home fights against. Insulation and draught-proofing aren’t just nice-to-haves — they directly lower the running cost. Cheaper levers to try first →
• Flow temperature matters. The cooler the water a heat pump has to send round your radiators, the more efficiently it runs. Bigger radiators or underfloor heating let it run at a lower flow temperature and cost less; a system asked to run hot to keep up loses efficiency.
• Versus a gas boiler, in principle. Electricity costs more per unit than gas, but a heat pump gets several units of heat per unit of electricity, where a boiler gets less than one unit of heat per unit of gas. So whether it’s cheaper to run comes down to the ratio between your electricity and gas prices and how efficiently the pump runs in your home — not a fixed rule.

Who does it suit? Homes that are reasonably well insulated, on (or willing to move to) a tariff that suits electric heating, and happy with steady warmth rather than quick blasts. The only reliable way to price it is against your home and usage, not a typical one — which is exactly what Joulely models, free and impartial, with nothing sold. See which tariff suits your usage →