Heat pumps
A heat pump is a heating system design job, not a boiler swap
Heat pumps work well in a very wide range of British homes, including older ones. What varies is the design work needed to get there, the cost of that work, and whether your running costs go up or down afterwards.
Research snapshot: September 2026
What suitability actually depends on
Five things decide the outcome. The brand of the unit is not one of them.
Heat loss
A room-by-room heat loss calculation sets the size of the unit and the emitters. A design based on floor area or on your old boiler rating is not a design.
Emitters
Radiators sized for a hot boiler may be too small for a heat pump. Some will need upgrading; underfloor heating suits heat pumps particularly well.
Flow temperature
The lower the flow temperature, the more efficient the system. Good design chases low flow temperatures rather than accepting high ones.
Insulation and airtightness
Reducing heat loss first shrinks the unit, the emitters and the running cost. Loft and draught work is usually the cheapest kilowatt you will ever buy.
Current heating and fuel
Replacing oil, LPG or old electric heating often looks very different financially from replacing an efficient mains gas boiler.
Space and siting
Outdoor unit position, pipe routes, noise, and room for a hot water cylinder. Not every home has an easy answer to the cylinder question.
Running costs: be honest about the comparison
Not every home saves money by installing a heat pump. Electricity currently costs more per unit than mains gas in the UK, so a heat pump only reduces your heating bill if its efficiency is high enough to outweigh that price gap. A well designed system running at low flow temperatures can do exactly that. A poorly designed one pushed to run hot may not.
Homes on oil, LPG or direct electric heating tend to see the clearest running cost improvement. Homes replacing a modern, efficient gas boiler should treat cost neutrality as a realistic outcome and judge the decision on comfort, carbon and the age of the boiler as well.
Ask any installer for the predicted seasonal efficiency of the design, the assumed flow temperature, and the electricity tariff used in their running cost estimate. Those three numbers explain almost the entire result.
Grants: Boiler Upgrade Scheme
England and Wales
The Boiler Upgrade Scheme provides £7,500 towards eligible air-to-water and ground-source heat pump installations, and £9,000 for certain eligible off-gas-grid properties. The scheme runs until 31 March 2027. The grant is applied for by your installer on your behalf and comes off the quoted price rather than being paid to you.
Eligibility conditions apply, including the property type, the equipment, and the installer's accreditation. Scotland and Northern Ireland operate separate support arrangements, so check the scheme for your own nation rather than assuming this one applies.
Checked September 2026. Sources: GOV.UK Boiler Upgrade Scheme guidance, Ofgem scheme pages.
Installer and certification considerations
Grant schemes generally require installation by an accredited installer working to the relevant standards, with MCS certification being the usual route in the UK. That certification matters for the grant, and it is also a proxy for whether anyone will stand behind the design.
Ask to see an actual heat loss survey rather than a summary, and ask which rooms need emitter changes. A quote that arrives without a survey is a price for equipment, not for a working heating system.
Questions to ask
- Can I see the room-by-room heat loss calculation for my home?
- What design flow temperature are you targeting, and at what outside temperature?
- Which radiators need replacing, and is that included in the price?
- What seasonal efficiency do you predict, and what does that mean in pounds at my tariff?
- Where will the outdoor unit and cylinder go, and what noise assessment applies?
- Are you registered for the relevant grant scheme, and is the quote net of the grant?
- What controls are fitted, and will the system run continuously rather than in short bursts?
- What insulation or draughtproofing would you do first if this were your house?
Your electricity price becomes the number that matters
A heat pump shifts your heating onto electricity, so the value of cheaper daytime power changes the whole picture. The solar calculator is the quickest way to see what that is worth in your house.