A combi-storage heat pump costs roughly £3,000 to £5,000 more than a standard gas boiler, but can cut heating bills by 40–60% annually.
If you are replacing a gas boiler and considering a heat pump, the combi-storage type offers a compact all-in-one alternative. It typically costs £8,000 to £14,000 installed, compared to £4,000 to £6,000 for a gas boiler replacement, but annual heating bills can fall by £300 to £600. The higher upfront cost is partly offset by the £7,500 Boiler Upgrade Scheme grant, bringing the net price to £500 to £6,500.
A combi-storage heat pump costs £8,000–£14,000 installed, roughly £3,000–£5,000 more than a gas boiler, but cuts annual heating bills by 40–60% (£300–£600 savings). The £7,500 Boiler Upgrade Scheme grant brings the net price down to £500–£6,500.
- Installed cost is £8,000–£14,000, £3,000–£5,000 more than a gas boiler.
- Annual heating bills drop by 40–60%, saving £300–£600 per year.
- The £7,500 Boiler Upgrade Scheme grant reduces net cost to £500–£6,500.
- Combines heat pump and hot water cylinder in one compact indoor unit.
- Requires radiator upgrades (£1,500–£3,000) if existing ones are undersized.
- A combi-storage heat pump costs roughly £3,000 to £5,000 more than a standard gas boiler, but can cut heating bills by 40–60% annually.
- A combi-storage heat pump combines a heat pump with an integrated hot water cylinder, replacing both a boiler and a separate tank.
- The total installed cost for a combi-storage heat pump in the UK is typically £8,000–£14,000, depending on property size and existing heating system.
- Running costs are 40–60% lower than a gas boiler, saving a typical three-bedroom home £300–£600 per year on heating and hot water.
- Quick numbers
- The Boiler Upgrade Scheme gives you £7,500 off the upfront cost, making payback achievable within 5–10 years.
- A combi-storage heat pump works best in well-insulated homes with existing radiators sized for lower flow temperatures (45–55°C).
- To qualify for the grant and ensure a safe installation, you must use an MCS-certified installer who also holds TrustMark registration.
A combi-storage heat pump combines a heat pump with an integrated hot water cylinder, replacing both a boiler and a separate tank.
This system uses a single outdoor unit connected to a compact indoor unit that contains a small buffer tank and a hot water cylinder, typically 100 to 200 litres (Energy Saving Trust, 2026). It provides both space heating via radiators or underfloor heating and instant hot water, without needing a separate hot water cylinder in an airing cupboard. Unlike a standard heat pump, it does not require a large external hot water tank, making it suitable for homes with limited indoor space. The indoor unit operates like a combi boiler, delivering hot water on demand, but uses a small storage tank to pre-heat water for faster delivery.
The total installed cost for a combi-storage heat pump in the UK is typically £8,000–£14,000, depending on property size and existing heating system.
The heat pump unit itself costs £4,000 to £7,000, with installation adding £3,000 to £5,000 for pipework, electrical upgrades, and commissioning (DESNZ, 2026). Additional costs may include radiator upgrades to larger, lower-temperature models at £1,500 to £3,000, if existing radiators are undersized for heat pump output. Labour costs vary by region; London and South East installations are typically 15 to 20 percent higher than the UK average, according to MCS installer survey data.
Running costs are 40–60% lower than a gas boiler, saving a typical three-bedroom home £300–£600 per year on heating and hot water.
A combi-storage heat pump with a Seasonal Coefficient of Performance (SCOP) of 3.5 uses roughly 3,500 kWh of electricity annually for 12,000 kWh of heat output. At the 2026 average electricity price of 24.5p/kWh under the Ofgem price cap, this costs approximately £858 per year for heating and hot water (Ofgem, Jan 2026). A comparable gas boiler at 90 percent efficiency would use 13,333 kWh of gas at 6.0p/kWh, costing £800 per year, plus a £200 to £300 annual gas standing charge. The net saving is £300 to £600 per year, depending on gas and electricity tariff rates and the property’s heat demand (Energy Saving Trust, 2026).
Quick numbers
| Metric | Value | Source |
|---|---|---|
| Average installed cost | £8,000–£14,000 | MCS installer survey (2026) |
| Annual running cost (typical 3-bed home) | £858 | Ofgem price cap (Jan 2026) + EST heat demand model |
| Annual saving vs gas boiler | £300–£600 | EST comparison (2026) |
| Typical SCOP | 3.5 | MCS product database (2026) |
| Hot water cylinder capacity | 100–200 litres | Manufacturer specifications |
| Grant available (Boiler Upgrade Scheme) | £7,500 | GOV.UK (2026) |
The Boiler Upgrade Scheme gives you £7,500 off the upfront cost, making payback achievable within 5–10 years.
The UK government’s Boiler Upgrade Scheme (BUS) offers a flat £7,500 grant for air-source heat pumps, including combi-storage models, applied as a discount at point of sale (GOV.UK, 2026). After the grant, your net cost is £500 to £6,500, based on total cost of £8,000 to £14,000 minus £7,500. Payback period is calculated by dividing net cost (£500–£6,500) by annual saving (£300–£600), giving 1 to 11 years, but realistically 5 to 10 years for most homes. The grant is currently confirmed through the 2027–28 financial year and may be extended or revised.
A combi-storage heat pump works best in well-insulated homes with existing radiators sized for lower flow temperatures (45–55°C).
The system delivers heat at lower temperatures of 45 to 55°C compared to a gas boiler’s 60 to 80°C, so radiators must be larger or upgraded to maintain comfort (Energy Saving Trust, 2026). Homes with cavity wall insulation achieving a U-value of 0.30 W/m²K or less and loft insulation of 270mm or more achieve the highest efficiency and lowest running costs. Underfloor heating is ideal but not essential; oversized radiators such as double panel convector types are sufficient for most homes. The integrated hot water cylinder pre-heats water to 50 to 60°C, reducing the need for an immersion heater backup, which would add cost.
To qualify for the grant and ensure a safe installation, you must use an MCS-certified installer who also holds TrustMark registration.
The Boiler Upgrade Scheme requires the installer to be MCS-certified under the Microgeneration Certification Scheme and registered with TrustMark for consumer protection (GOV.UK, 2026). MCS certification ensures the installer follows standards for heat pump sizing, installation, and commissioning under MIS 3005. TrustMark provides a dispute resolution process and guarantees work meets government-endorsed quality standards. You can verify an installer on the MCS website at mcscertified.com or TrustMark at trustmark.org.uk before hiring.
Frequently Asked Questions
The total installed cost in the UK is typically £8,000 to £14,000, depending on property size and existing heating system. This includes the heat pump unit (£4,000–£7,000) and installation labour (£3,000–£5,000), according to DESNZ (2026).
Yes, running costs are 40–60% lower than a gas boiler, saving £300 to £600 per year on heating bills. The Energy Saving Trust confirms these savings for typical UK homes.
Yes, the £7,500 Boiler Upgrade Scheme grant applies to combi-storage heat pumps, reducing the net cost to £500–£6,500. The grant is available for eligible homeowners in England and Wales, as per GOV.UK (2026).
No, a combi-storage heat pump integrates a small hot water cylinder (100–200 litres) inside the indoor unit, so you don't need a separate tank. It delivers hot water on demand like a combi boiler, using a buffer tank for faster delivery.
For a typical 3-bed semi-detached house, a 5–8 kW combi-storage heat pump is usually sufficient. The MCS installer should calculate the exact size based on your home's heat loss and hot water demand.
