DESNZ's figures show that 10% of grant-funded heat pumps installed between May 2022 and September 2026 replaced direct electric heating, and 13% went into homes with no previous heating system at all. For these homes the installation is a different scale of project from a gas boiler swap, and it is worth knowing that before the first quote.
Why the job is bigger
A gas home already has a wet heating system: pipes and radiators that carry hot water. A heat pump can usually reuse much of it. Storage heaters and panel heaters are each self-contained electric appliances, so there is nothing to connect to. An air-to-water heat pump needs the full system built:
- An outdoor unit and the pipe run into the house.
- Pipework to every room that will have a radiator.
- Radiators, or underfloor heating, each sized for the room.
- A hot water cylinder, unless one is already in use with an immersion heater.
- Controls, and the electrical supply to the heat pump.
The storage heaters then come out, and their dedicated electric circuits may be removed or reused.
Designing from scratch
With no existing radiators, the design starts from a clean sheet, which has an advantage: every radiator can be sized for the heat pump's flow temperature from the start, rather than checked against what was there. The heat-loss survey gives each room's heat loss, and the design turns that into a radiator schedule and a pipe layout. Ask to see both on paper, with the routes the pipes will take.
The pipe routes are the part that most affects the house. Under suspended timber floors they can often run out of sight; with solid floors they may need to run along walls or through boxing. These are decisions to make with the installer before you accept the quote, not on the day.
Hot water
Many homes with storage heaters already heat water with an immersion heater in a cylinder. That cylinder will usually be replaced with one designed to be heated by a heat pump, and the design should say where it goes and how big it is. Homes that heat water at the tap with an electric shower or instant heater will need space found for a cylinder.
Cost and the grant
DESNZ does not publish prices by previous heating type, so the official median of £12,826 for July to September 2026 covers gas, oil and electric homes together. Expect a quote for a home without a wet system to sit higher in the range for its size band, because of the pipework and radiators; the cost page shows each band, from £11,494 at 4 to 6 kW upwards.
The grant is £7,500 for an air-to-water or ground source heat pump replacing electric heating, if you own the property and an MCS certified installer applies. The higher £9,000 rate does not apply to electric homes, even off the gas grid: it is only for homes with no mains gas connection replacing oil or LPG, for applications made by 31 March 2027.
Planning the work
Because the job touches every room, schedule it with care. Ask the installer for the order of work room by room, how long each area will be disturbed, and when the old heaters will be disconnected relative to the new system starting, so that you are not left without heat in between. Keep the job inside the grant voucher's 3 months for air source. The installation checklist lists everything to have in writing before you accept a quote.