Heat pump installation: one request, one installer

Most UK installations are air-to-water air source heat pumps: an outdoor unit that feeds your radiators or underfloor heating and a hot water cylinder. They suit most houses with space for the unit outside and room for a cylinder inside.

Ground source heat pumps take heat from pipework buried in trenches or boreholes. They run more steadily through a cold spell, but the groundworks make them far more expensive, and they only make sense where there is land to dig or a budget for drilling.

Air-to-air heat pumps blow warm air into rooms, much like air conditioning, and do not heat your hot water. They can now receive a smaller Boiler Upgrade Scheme grant, so they are an option for flats or homes where a wet system is impractical, as long as you have another way to heat water.

The size of the heat pump should come from a room-by-room heat loss calculation: wall and floor construction, glazing, insulation, ventilation and the indoor temperature you want to hold on a cold day. It should not come from the output of the boiler you are replacing, which was often oversized in the first place.

The same calculation tells the installer which radiators can stay and which need to be larger. A heat pump is most efficient at low flow temperatures, so an undersized radiator in a north-facing bedroom is the difference between a warm room and a system that has to run hot all winter. Ask to see the room-by-room figures, not just the headline kW.

Hot water is a separate question. A combi boiler heats water on demand; a heat pump heats a stored cylinder. The installer needs to know how many people live in the house and how you use hot water to size the cylinder and find a place for it.

• a room-by-room heat loss calculation and the design flow temperature
• which radiators are replaced or upsized, and whether pipework changes
• cylinder size and position, and what happens to the old boiler and tanks
• where the outdoor unit goes, and the noise assessment for that position
• whether the electricity supply or fuse needs upgrading
• the MCS certificate, commissioning and handover of the controls

In England, an air source heat pump on a house is usually permitted development, which means no planning application, as long as it meets the conditions set out by the Planning Portal. The outdoor unit must not exceed 1.5 cubic metres on a house, the installation has to comply with the MCS 020a planning standard, and pitched-roof installations are not permitted development.

Detached houses may have two units under permitted development; other houses and blocks of flats one. In a conservation area or World Heritage Site the unit must not go on a wall or roof facing a highway. Listed buildings have no permitted development rights for heat pumps, so you need consent from the council first.

Wales, Scotland and Northern Ireland have their own rules. A good installer checks this before quoting and tells you if the position you want needs an application.

Source: planningportal.co.uk

The Boiler Upgrade Scheme covers England and Wales. You must own the property and be replacing fossil fuel heating such as gas, oil, LPG or direct electric. The installer applies on your behalf through Ofgem, Ofgem contacts you to confirm, and the grant is paid to the installer and taken off your bill. Most new builds and social housing are not eligible, and the installer has 120 days from the application to install and commission the system.

In Scotland, Home Energy Scotland offers its own grant and interest-free loan. In Wales, the Nest scheme can fund heat pumps for eligible households. Low-income households in England may also qualify through the Warm Homes: Local Grant from their council or through ECO4, which runs until 31 December 2026. The installation of heat pumps in homes is currently zero-rated for VAT.

Grant rules change. The details below come from the official scheme pages at the date shown on this page; your installer should confirm your eligibility before you sign.

Source: gov.uk · ofgem.gov.uk

You answer a few questions about the property, the current heating and your timescale, and confirm your phone number by text message and your email address by link. We then offer the request, without your name or contact details, to heat pump installers in your area. Exactly one of them can buy it; it pays Offrano for it, and the service is free for you.

Before the installer sees your details, we email you its name, address and phone number. We cannot promise that an installer will take up every request, and you are never obliged to accept a quote. Offrano checks that buyers are registered businesses; it does not inspect their work, so check the MCS certificate number yourself on the MCS website before you sign anything.