Why quotes differ so much
Equipment is only one part of the job. Cylinder space, electrical capacity, pipework, radiator changes, access and the target flow temperature can move the price substantially. A quote issued without a proper heat-loss assessment is still an early estimate.
What determines running cost?
The key number is seasonal performance, usually expressed as SPF or seasonal COP. It depends on the home, weather, emitter sizing, flow temperature and system control. Electricity is more expensive per unit than gas, so efficiency and tariff matter.
Ask for the design, not only the machine
The installer should share room-by-room heat loss, design outdoor temperature, flow temperature, emitter schedule and expected seasonal performance before work begins.
What support is available?
The Boiler Upgrade Scheme currently provides £7,500 for eligible air-to-water and ground-source heat pumps in England and Wales. Ofgem states that eligible off-gas-grid properties can receive £9,000 from 21 July 2026 until 31 March 2027. Scotland and Northern Ireland have different routes. Always check the official scheme page before committing.
What a useful heat-pump quote should show
- Room-by-room heat-loss calculation and chosen design temperature.
- Heat-pump output at the design condition—not only the model name.
- Target flow temperature and every radiator or emitter change.
- Cylinder, controls, electrical work, pipework and making good.
- Modelled SPF, warranties, MCS certification and aftercare.