At a glance
| Air source heat pump | Gas boiler | |
|---|---|---|
| Installed cost | £8,000 to £16,000 (£500 to £8,500 after grant) | £2,000 to £4,000 |
| Grant available | £7,500 (BUS) | None |
| Efficiency | 300 to 400% | 85 to 92% |
| Lifespan | ~20 years | 10 to 15 years |
| Annual servicing | Recommended | Recommended |
| CO₂ per year (3-bed) | ~0.7 tonnes | ~2.5 tonnes |
| Hot water | Stored cylinder | Instant (combi) or cylinder |
Upfront cost
A like-for-like gas boiler swap is cheaper upfront. But with the £7,500 Boiler Upgrade Scheme grant, the gap narrows dramatically: many three-bed homes pay £2,500 to £5,500 for a heat pump, against £2,000 to £4,000 for a new boiler. Because a heat pump lasts longer, the cost per year of service is closer still. See typical heat pump prices.
Running costs
Gas is cheaper per kWh than electricity, but a heat pump needs far fewer kWh. For a home needing 12,000 kWh of heat a year, a gas boiler burns around 13,300 kWh of gas, while a heat pump with a SCOP of 3.5 uses around 3,400 kWh of electricity. On a heat pump tariff that typically makes the heat pump cheaper to run; on a standard tariff, it's roughly level. Pair it with solar panels and the balance tips further.
Comfort and convenience
- Steady warmth. Heat pumps run longer at lower temperatures, so rooms stay at an even temperature rather than cycling hot and cold.
- No gas, no flue, no annual gas safety check. And no carbon monoxide risk.
- Hot water from a cylinder. If you have a combi boiler, you'll need space for a cylinder.
- Some can cool too. Certain models can run in reverse in summer.
Air source heat pump vs oil and LPG boilers
For off-gas homes, the case for a heat pump is strongest. Oil and LPG cost more per kWh than mains gas and prices swing with world markets. Switching to a heat pump removes the tank, the deliveries and the price spikes, and most off-grid homes see their heating bills fall. Get an oil-to-heat-pump quote.
The verdict
If your boiler is near the end of its life, a heat pump is now a realistic, often cheaper-over-time alternative, especially with the £7,500 grant and 0% VAT. The key is a properly designed system: ask for a room-by-room heat loss calculation and a stated SCOP in your quote.
Sources
Grant amounts, VAT rules and eligibility are set by government and the scheme administrators. We check them against these primary sources:
- Apply for the Boiler Upgrade Scheme (GOV.UK)
- Energy price cap and standing charges explained (Ofgem)
- VAT on energy-saving materials and heating equipment (VAT Notice 708/6) (GOV.UK)
- Microgeneration Certification Scheme (MCS)
New to the jargon? See the heat pump glossary, or browse the heat pump FAQs.