Heat Pumps: The Complete UK Guide 2025
Air source and ground source heat pumps explained – costs, savings, grants, and whether a heat pump is right for your home.
Air Source vs Ground Source Heat Pumps
Both extract renewable heat from the environment, but they work differently and suit different properties:
| Feature | Air Source (ASHP) | Ground Source (GSHP) |
|---|---|---|
| How it works | Extracts heat from outside air | Extracts heat from underground via buried loops |
| Installation cost | £7,000–£14,000 | £15,000–£35,000 |
| After BUS grant | £0–£6,500 | £7,500–£27,500 |
| Efficiency (COP) | 2.8–3.5 | 3.5–4.5 |
| Space needed | External wall space (outdoor unit) | Large garden for ground loops or borehole |
| Planning permission | Usually not needed | Usually not needed |
| Noise | 40–50 dB (outdoor unit) | Silent (underground loops) |
| Best for | Most homes, especially retrofits | New builds, rural homes with land |
| Lifespan | 20–25 years | 25–30 years (loops last 50+) |
Heat Pump Running Costs
Heat pumps are cheaper to run than gas boilers in most scenarios, especially with good insulation:
| Heating System | Fuel Cost (p/kWh) | Efficiency | Cost per kWh of Heat | Annual Cost (3-bed semi) |
|---|---|---|---|---|
| Air Source Heat Pump | 24.5p (electricity) | 300% (COP 3.0) | 8.2p | £950–£1,200 |
| Ground Source Heat Pump | 24.5p (electricity) | 400% (COP 4.0) | 6.1p | £750–£950 |
| Gas Boiler (new) | 6.8p (gas) | 92% | 7.4p | £900–£1,100 |
| Oil Boiler | 7.5p (oil) | 90% | 8.3p | £1,000–£1,250 |
| Direct Electric | 24.5p (electricity) | 100% | 24.5p | £2,800–£3,500 |
| LPG Boiler | 10.5p (LPG) | 90% | 11.7p | £1,400–£1,700 |
Boiler Upgrade Scheme (BUS) Grant
Get £7,500 Off Your Heat Pump
The UK Government’s Boiler Upgrade Scheme provides grants to help homeowners switch from fossil fuel heating to heat pumps:
| Detail | Information |
|---|---|
| Grant amount | £7,500 for air source or ground source heat pumps |
| Available until | March 2028 (extended in Autumn Statement 2023) |
| Who can apply | Homeowners in England and Wales replacing fossil fuel heating |
| EPC requirement | Valid EPC with no outstanding loft/cavity wall recommendations (or evidence they’re unsuitable) |
| How to apply | Your MCS-certified installer applies on your behalf |
| Processing time | Typically 3–6 weeks |
Best Heat Pump Brands in the UK
| Brand | Type | COP Range | Noise Level | Warranty | Price Range |
|---|---|---|---|---|---|
| Daikin | ASHP | 3.0–4.5 | 38–46 dB | 5 years | £7,000–£11,000 |
| Mitsubishi Ecodan | ASHP | 3.0–4.2 | 40–48 dB | 5 years | £7,500–£12,000 |
| Vaillant aroTHERM | ASHP | 3.0–4.0 | 42–50 dB | 7 years | £8,000–£13,000 |
| Samsung EHS | ASHP | 3.0–3.8 | 41–47 dB | 5 years | £6,500–£10,000 |
| Nibe | ASHP/GSHP | 3.5–5.0 | 36–44 dB | 7 years | £8,000–£14,000 |
| Kensa | GSHP | 4.0–5.0 | Silent | 5 years | £15,000–£25,000 |
Pros and Cons
Advantages
- 300–400% efficient – far more than gas or oil boilers
- £7,500 BUS grant slashes upfront cost
- Lower running costs than most heating systems
- Significantly reduces your carbon footprint
- Can provide heating and hot water year-round
- 20–25 year lifespan (longer than boilers)
- Works even at -15°C outside temperature
- Can reverse to provide cooling in summer
Disadvantages
- High upfront cost (even with grant)
- Requires good home insulation to be effective
- May need larger radiators or underfloor heating
- Lower flow temperatures than gas boilers (45–55°C vs 60–80°C)
- Air source units produce some outdoor noise
- Ground source needs garden space for loops
- Electricity costs must stay reasonable for savings to hold
- Installation takes 2–5 days (more disruptive than boiler swap)
Is Your Home Suitable?
Suitability Checklist
Heat pumps work best in well-insulated homes. Check these factors:
| Factor | Ideal | May Need Work |
|---|---|---|
| Wall insulation | Cavity or solid wall insulation fitted | Uninsulated solid walls – consider EWI |
| Loft insulation | 270mm+ mineral wool or equivalent | Less than 100mm |
| Windows | Double or triple glazed | Single glazed throughout |
| Radiators | Correctly sized or underfloor heating | Very small radiators need upgrading |
| Space | Wall space for outdoor unit (ASHP) or garden (GSHP) | No suitable external wall or garden |
| Current heating | Gas, oil, LPG, or electric (replacing fossil fuel) | Already on mains gas with new boiler |
Frequently Asked Questions
Do heat pumps work in cold UK winters?
Yes. Modern air source heat pumps work efficiently down to -15°C or even -25°C. The UK rarely drops below -5°C, so heat pumps perform well year-round. In very cold snaps, the COP drops slightly but the system still heats your home effectively.
Can a heat pump replace my gas boiler?
Absolutely. A properly sized heat pump provides all the heating and hot water a gas boiler does. You may need to upgrade some radiators to larger ones or add underfloor heating to work with the lower flow temperatures. Your installer will assess this during the survey.
How noisy are heat pumps?
Modern air source heat pumps produce 40–50 dB at 1 metre – similar to a fridge or quiet conversation. Planning rules require noise below 42 dB at your nearest neighbour’s window. Most premium models are well within this. Ground source heat pumps are virtually silent.
How long does installation take?
An air source heat pump typically takes 2–3 days to install. Ground source takes 3–5 days (longer if drilling boreholes). If radiator upgrades or underfloor heating are needed, add 1–3 days. The BUS grant application adds 3–6 weeks before work begins.
Will I still need a boiler as backup?
No. A correctly designed heat pump system is your sole heating source. However, some hybrid systems pair a heat pump with a gas boiler for peak demand. This is more common in poorly insulated homes where a full heat pump solution isn’t yet cost-effective.
What’s the payback period?
With the £7,500 BUS grant, an air source heat pump replacing an oil or LPG boiler can pay back in 5–8 years. Replacing gas is longer (8–12 years) due to cheaper gas prices, but this improves as the gas price gap narrows and electricity costs fall with more renewables.
Heat Pump Buyer’s Checklist
- Get a valid EPC for your property (needed for BUS grant)
- Address any loft/cavity wall insulation recommendations on your EPC
- Get at least 3 quotes from MCS-certified heat pump installers
- Ask each installer about expected COP for your specific home
- Check if radiator upgrades or underfloor heating is recommended
- Confirm the installer will handle BUS grant application
- Ask about smart controls and weather compensation
- Check noise levels and placement options for the outdoor unit
- Understand the warranty terms (unit, compressor, labour)
- Plan for the 3–6 week BUS grant processing time
Ready to Switch to a Heat Pump?
Compare quotes from MCS-certified installers and claim your £7,500 BUS grant.