A heat pump for a one-bedroom flat costs £2,500 to £5,500 fully installed after the Boiler Upgrade Scheme grant.
The typical installed cost before any grant is £7,000 to £9,000 for a small air-source heat pump system suitable for a one-bedroom flat (Energy Saving Trust, 2026). The Boiler Upgrade Scheme (BUS) grant of £7,500 (as of 2026) reduces the upfront cost to between £2,500 and £5,500 (GOV.UK, 2026). Costs vary significantly by property type: a flat with good insulation and a small heat load will be at the lower end; a flat needing new radiators or a hot water cylinder will be higher.
The running cost of a heat pump in a one-bedroom flat is £400–£700 per year
Annual heating and hot water for a well-insulated one-bedroom flat using a heat pump typically costs between £400 and £700 (Energy Saving Trust, 2026). A gas boiler in the same flat would cost approximately £350–£600 per year, making the heat pump slightly more expensive to run but often within 10–20%. Electricity is currently around 24–28p/kWh (Ofgem price cap, Q1 2026) versus gas at 6–7p/kWh, but the heat pump’s efficiency (SCOP of 3.0–4.0) narrows the gap (Ofgem, 2026).
Quick numbers upfront cost, running cost, and payback for a one-bedroom flat.
| Metric | Low estimate | High estimate | Source |
|---|---|---|---|
| Upfront cost (before grant) | £7,000 | £9,000 | Energy Saving Trust, 2026 |
| Upfront cost (after £7,500 BUS grant) | £2,500 | £5,500 | GOV.UK, 2026; MCS, 2026 |
| Annual running cost (heat pump) | £400 | £700 | Energy Saving Trust, 2026 |
| Annual running cost (gas boiler) | £350 | £600 | Ofgem, 2026 |
| Typical payback period (years) | 8 | 15 | DESNZ, 2026 |
| Annual CO2 saving (kg) | 1,500 | 2,500 | Energy Saving Trust, 2026 |
A heat pump is the direct answer to replacing a gas boiler in a one-bedroom flat if you want lower carbon emissions and no gas standing charge.
For a one-bedroom flat, an air-source heat pump is the most common and cost-effective low-carbon heating option available in 2026 (DESNZ, 2026). It eliminates the gas standing charge (around £100–£150 per year) and reduces household carbon emissions by roughly 1.5–2.5 tonnes per year compared to a gas boiler (Energy Saving Trust, 2026). The system typically consists of an outdoor unit (about the size of a washing machine) and an indoor unit or hot water cylinder, which can fit in a small cupboard.
Eligibility for the Boiler Upgrade Scheme grant depends on your flat’s insulation level and your installer’s certification.
The BUS grant of £7,500 is available to homeowners and some landlords in England and Wales; Scotland has its own separate scheme (Home Energy Scotland) (GOV.UK, 2026). Your flat must have a valid Energy Performance Certificate (EPC) with no recommendations for loft or cavity wall insulation outstanding (GOV.UK, 2026). The installer must be MCS-certified (Microgeneration Certification Scheme) and registered with TrustMark to process the grant (MCS, 2026; TrustMark, 2026).
You must use an MCS-certified installer to qualify for the grant and to ensure correct system sizing for a one-bedroom flat.
Only MCS-certified installers can apply for the BUS grant on your behalf; the grant is deducted from the invoice, not paid to you later (GOV.UK, 2026). A properly sized heat pump for a one-bedroom flat typically has an output of 3–5 kW, which is smaller than a standard gas boiler (often 24 kW) (MCS, 2026). The installer must perform a heat loss calculation (using MCS standards) to confirm the flat’s heat demand and ensure the system is not oversized (Energy Saving Trust, 2026). Heat pump sizing guide for small flats
The long-term savings from a heat pump in a one-bedroom flat come from the gas standing charge removal and potential tariff switching.
Removing the gas connection saves the standing charge of £100–£150 per year, which can offset higher electricity unit costs (Ofgem, 2026). Switching to a heat-pump-specific electricity tariff (e.g., Economy 7, Octopus Cosy, or other time-of-use tariffs) can reduce running costs by 10–20% (Energy Saving Trust, 2026). Over a 10-year lifespan, total savings (versus a new gas boiler) can range from £500 to £2,000, depending on tariff and efficiency (DESNZ, 2026). Best electricity tariffs for heat pumps in 2026
Frequently Asked Questions
A heat pump for a 1-bedroom flat costs £2,500 to £5,500 after the £7,500 Boiler Upgrade Scheme grant (GOV.UK, 2026). Before the grant, the typical cost is £7,000 to £9,000 (Energy Saving Trust, 2026).
No, a heat pump is slightly more expensive to run than a gas boiler in a 1-bedroom flat. Annual running costs are £400 to £700 for a heat pump compared to £350 to £600 for gas (Energy Saving Trust, 2026).
The running cost of a heat pump in a flat is £400 to £700 per year for heating and hot water (Energy Saving Trust, 2026). This is based on a well-insulated 1-bedroom flat with a SCOP of 3.0 to 4.0.
Yes, the Boiler Upgrade Scheme covers flats as long as the property has a valid Energy Performance Certificate (EPC) and meets eligibility criteria (GOV.UK, 2026). The grant is £7,500 for air-source heat pumps.
The payback period for a heat pump in a 1-bedroom flat is 8 to 15 years compared to a gas boiler (DESNZ, 2026). This depends on the upfront cost after grant and your energy tariff.
