Heat Pump vs Gas Boiler: What to Weigh Up Before You Switch
Heat pumps are central to the UK's plan to cut home carbon emissions, but they are a big decision. This guide sets out how they compare with a gas boiler so you can ask the right questions before you get quotes.
How each system works
A gas boiler burns fuel to heat water. At best, a modern condensing boiler turns around 90 per cent of that gas into heat. An air source heat pump instead moves heat from the outside air into your home using electricity, much like a fridge in reverse. Because it moves heat rather than creating it, a well-installed heat pump can deliver roughly three units of heat for every unit of electricity it uses. This ratio is called the coefficient of performance, or COP.
Running costs
Electricity usually costs more per kWh than gas, so a heat pump only saves money if its efficiency outweighs that price gap. The result depends on your tariff, your home's insulation and how the system is set up. A heat pump on a time-of-use electricity tariff, or paired with solar panels, can improve the picture further. Ask any installer for a worked estimate using your actual current usage and rates.
Upfront cost and grants
Heat pumps cost more to install than a like-for-like boiler. Grants such as the Boiler Upgrade Scheme in England and Wales have been available to reduce the cost, and Scotland has its own support schemes. Eligibility and amounts change, so check the current rules on the government website before you commit.
Is your home ready?
- Insulation: a heat pump works best at lower flow temperatures, so loft, wall and draught improvements come first.
- Radiators: some may need to be larger to give out enough heat at lower temperatures.
- Hot water: you will usually need a cylinder, so check you have the space.
- Outside space: the outdoor unit needs clearance and should be sited with noise in mind.
Where a boiler still makes sense
If your home is poorly insulated, has very limited space, or you are planning to move soon, keeping an efficient boiler for now may be the practical choice. Boilers are cheaper up front and are familiar to every heating engineer. Insulating first will reduce your bills whichever system you eventually choose.
Questions to ask installers
Ask for a room-by-room heat loss calculation, the expected seasonal efficiency, the design flow temperature and the estimated annual running cost. Check that the installer is certified under the Microgeneration Certification Scheme, which is normally needed to claim a grant. Get at least three quotes and ask each to explain what they are assuming about your home.
A heat pump is neither a miracle nor a risk. It is a good fit for many homes and a poor fit for others, and the quality of the design and installation matters as much as the equipment itself.