THE EXETER FIELD GUIDE / AIR SOURCE HEAT PUMPS
An extension and original rooms may need different radiator changes. Separate their construction in an Exeter heat-loss survey.
START WITH THE PROPERTY
For an Exeter house with an extension, identify which rooms belong to each building phase and any different insulation or floor construction. Give that distinction to the surveyor before a single system size is proposed.
BEFORE YOU ACCEPT A QUOTE
Ask to see room losses, emitter outputs and design flow temperature together. If the extension is much easier to heat, the original rooms may still govern the radiator upgrades and running assumptions.
LOCAL COST EVIDENCE / OCTOBER 2026
A quoted installation price depends on the work inside the home. Electricity use depends on the finished design and tariff.
We could not verify a representative local average for a fully installed, family-sized system. Published installer figures mix starting prices, example homes and different scopes. Averaging them would suggest more certainty than the evidence allows.
For a useful comparison, ask each installer to itemise the heat pump, cylinder, radiator changes, electrical work and commissioning, then show the price before and after any eligible grant.
about £660approximate annual cost if the October–December 2026 unit rate lasted a full year
This is a model, not a measured bill or an average for families with heat pumps. It starts with 9,025 kWh, the 2024 mean annual domestic gas use per meter in Exeter. We apply 85% boiler efficiency and a heat pump seasonal performance factor of 3.1, then price the electricity at 26.58p per kWh in South Western England.
Calculation: 2024 mean gas kWh per domestic meter × 0.85 ÷ 3.1 × Ofgem electricity unit rate. The result is rounded to the nearest £10. It assumes the gas meter's entire use was for heating and hot water, so cooking and other gas use can make it too high. It does not include existing electricity standing charges, servicing, or changes to your other electricity use.
Gas consumption is by local authority, except London, which uses the London region. Oxfordshire combines its five districts by gas-meter count. The electricity rate follows the distribution region for the place; Oxfordshire spans two regions. Actual cost depends on your heat-loss survey, hot-water use, chosen tariff, controls and the installed system's measured performance. Ask the installer for a property-specific annual estimate.
ILLUSTRATIVE QUOTE COMPARISON
One quote averages old rooms and a well-insulated extension.
Another identifies original rooms with higher losses and prices their radiator changes.
Ask for both construction types in the room survey. The easy-to-heat extension cannot compensate for an under-sized radiator in the original house.
ANOTHER PROJECT AT THE SAME ADDRESS?
NEXT STEP IN EXETER
Once mixed room construction is measured, hot-water provision needs the same care. Photograph current plumbing and storage space so the quote includes the full change.