Heat pumps are the future of home heating in the UK. The government knows it, the boiler manufacturers know it, and the evidence from countries that made the transition earlier - Scandinavia, the Netherlands - confirms that they work well in climates comparable to Britain's.
But the transition involves real decisions and real costs. Here's what you actually need to know.
A heat pump works like a refrigerator in reverse - it extracts heat from the outside air (or ground) and moves it inside. Because it's moving heat rather than generating it, it produces 3-4 units of heat for every unit of electricity it uses. This efficiency ratio is called the Coefficient of Performance (COP).
A gas boiler is typically 85-92% efficient. A heat pump is typically 250-400% efficient. That difference is why heat pumps have significantly lower running costs despite electricity being more expensive per unit than gas.
Air source heat pumps (ASHP) extract heat from outdoor air and are suitable for most homes. They can be installed in a day, require a unit outside the house (roughly the size of an air conditioning unit), and cost between £8,000-£15,000 installed before the government grant.
Ground source heat pumps (GSHP) extract heat from the ground via pipes buried in the garden. They're more efficient than air source but significantly more expensive to install (£15,000-£30,000) and require sufficient garden space. They make sense for rural properties with larger gardens and higher heating demands.
For most UK homes, air source is the right choice.
The Boiler Upgrade Scheme (BUS) currently offers a £7,500 grant towards the cost of an air source or ground source heat pump. This is available to homeowners in England and Wales who are replacing a fossil fuel heating system. The grant is applied directly by your installer - you pay the net cost.
Check eligibility and find approved installers at gov.uk/boiler-upgrade-scheme.
Heat pumps work best in well-insulated homes. Before installing a heat pump, it's worth addressing loft insulation (270mm depth minimum), cavity wall insulation if applicable, and draughts around doors, windows and floors.
Heat pumps also typically run at lower flow temperatures than gas boilers (45-55°C vs 70-80°C). This means existing small radiators may need upgrading to larger ones, or underfloor heating is preferable. A good installer will carry out a heat loss calculation and specify the right system for your home.
The economics of heat pump running costs depend heavily on your electricity tariff. On a standard tariff, heat pump running costs are broadly comparable to gas in a well-insulated home. On an Octopus Cosy or Intelligent tariff - which offer significantly cheaper electricity during off-peak periods - heat pumps can be substantially cheaper to run than gas.
Look for MCS-certified installers - the Microgeneration Certification Scheme is the industry standard for quality and is required to access the government grant. The Heat Pump Association website has a directory of vetted installers. Get at least three quotes.
If your boiler needs replacing in the next few years, a heat pump is almost certainly the right choice - especially with the £7,500 grant. If your boiler is relatively new and working well, focus on insulation first and plan for a heat pump at the next replacement.
