Swansea and West Wales have access to both the BUS grant (£7,500) and the Welsh Nest scheme for eligible households. Rural Carmarthenshire and Pembrokeshire surrounding Swansea are predominantly off-gas — giving a much stronger financial case for heat pumps versus oil. The Nest scheme can provide completely free upgrades for qualifying households regardless of the system type. Welsh Government heat pump targets are ambitious.
Heat demand starts from typical UK figures by property type (detached ~14,000 kWh/yr, semi ~12,000, terrace ~10,000, flat ~6,000) and is adjusted for bedrooms and EPC rating. An EPC C home uses ~15% less heat than D; an F home uses ~30% more.
Heat pump electricity = heat demand ÷ SCOP. We assume SCOP 3.0 for ASHP, 4.0 for GSHP and 2.5 for air-to-air systems. Real-world SCOP depends on radiator sizing, hot water demand and your installer's setup quality.
Current cost uses 6.5p/kWh gas, 9p oil, 12p LPG. Override with your actual bill for a more accurate result.
Install costs: ASHP £10–14k typical, GSHP £18–25k (deeper bore + groundwork), air-to-air £4–7k. The Boiler Upgrade Scheme grant is deducted. We compare against the cost of replacing a like-for-like boiler (~£3,000) to give an honest "incremental" payback.
Estimates only. SCOP is highly installer-dependent and your savings hinge on getting the radiator sizing right. Get at least 3 quotes from MCS-certified installers.