Should I get a heat pump?

A heat pump moves heat rather than generating it, which is why it can deliver more energy than it consumes. The catch is that it delivers that heat at a much lower temperature than a gas boiler, and everything about whether it works well follows from that.

Safety

Step by step

1. Understand the low-temperature principle.A gas boiler sends water to radiators at perhaps 65-75°C. A heat pump works most efficiently at 35-50°C. The same radiator emits much less heat at the lower temperature, which is why the rest of this matters.
2. Assess the insulation first.A house that loses heat quickly needs a high flow temperature to keep up, which is exactly where a heat pump is least efficient. Loft insulation, draught-proofing and cavity or solid wall insulation come before the heat pump, not after.
3. Expect radiators to need upsizing.Many existing radiators are too small to heat their room at 45°C. Some or all usually need replacing with larger ones, and that cost belongs in the comparison rather than as a surprise afterwards.
4. Insist on a room-by-room heat loss survey.Not an estimate from floor area. A proper survey calculates each room's heat loss and sizes the emitters and the unit accordingly. A design done properly is the single biggest predictor of a good outcome.
5. Beware oversizing.A unit larger than the house needs cycles on and off in mild weather, which is inefficient and wears the compressor. Oversizing is more common than undersizing and is harder to notice.
6. Check where the outdoor unit can go.It needs space, clear airflow, and consideration of noise for you and your neighbours. Planning permission is often not required under permitted development, but the conditions differ between England, Wales, Scotland and Northern Ireland and they are worth checking for where you live.
7. Understand the hot water arrangement.Heat pumps normally need a hot water cylinder rather than heating on demand. That needs space, and it changes how hot water behaves compared with a combi boiler.
8. Compare running costs honestly.Efficiency is expressed as a coefficient of performance — units of heat per unit of electricity, typically around three. Whether that is cheaper than gas depends on the electricity-to-gas price ratio and on the flow temperature the design achieves.
9. Look at the tariff.Heat pump running costs change substantially on a time-of-use electricity tariff, particularly combined with a well-insulated house that holds heat. This is a large part of the arithmetic and is frequently left out.
10. Check what grants currently exist.Government schemes have supported heat pump installation and the amounts and conditions change. Confirm the current position and eligibility before doing any sums.
11. Expect to run it differently.Heat pumps work best running gently and continuously at a low flow temperature, not in short hard bursts. Households that operate one like a gas boiler get worse results and higher bills.
12. Get several quotes and compare the designs.Compare the flow temperature each design targets, the radiator changes proposed and the survey behind them, not just the price. The cheapest quote is often the one that skipped the survey.
13. Consider the alternative order.For many houses, insulation and draught-proofing first, then reassess, gives a better result and a smaller heat pump. It is rarely the sequence people are sold.

Tips

• Ask any installer what flow temperature the design targets. A confident specific answer is a good sign; vagueness is not.
• Talk to someone locally who has one. Real running costs in a comparable house tell you more than any calculator.
• If a quote does not include a room-by-room heat loss calculation, treat it as incomplete regardless of the price.

Common mistakes

• Installing before improving insulation — A leaky house needs a high flow temperature, which is where a heat pump is least efficient. Insulation first usually means a smaller unit and better running costs.
• Keeping the existing radiators without checking — Radiators sized for 70°C water are frequently too small at 45°C, so rooms never reach temperature. That cost belongs in the decision, not in a later surprise.

Questions people ask