Glossary · Heat pumps, grants and regulations
Heat pump vs gas boiler: what is the difference?
A gas boiler burns gas to make heat. A heat pump uses electricity to move heat from outside air, ground or water into your home, so it delivers several units of heat for each unit of electricity. A boiler runs hotter and needs little from the house. A heat pump runs cooler and works best in a well-insulated one.
Key points
- A boiler creates heat by burning gas. A heat pump moves existing heat, which Daikin says gives it a SCOP of 3 to 4 against 0.99 to 1.09 for a condensing boiler.
- Heat pumps deliver steady, lower-temperature heat, so radiators may need to be larger and insulation matters more.
- The Boiler Upgrade Scheme pays £7,500 towards an air source heat pump if you replace a fossil fuel system, through an MCS certified installer.
- Gas boiler work must be done by a Gas Safe registered engineer. Heat pump refrigerant work needs an F gas qualification.
- Running costs depend on gas and electricity prices and on the home, so ask for both options to be quoted side by side.
How the two work
A gas boiler burns gas to create heat. A heat pump does not create heat. Daikin says it extracts thermal energy from the air, ground or water and moves it into the home, much as a fridge works in reverse.[1]Daikin UK, How does a heat pump work? Because it moves heat, it can deliver more heat than the electricity it uses: for 1 kWh of electricity you get 3 to 4 kWh of heat, a SCOP of 3 to 4. Daikin gives modern condensing gas boilers 99 to 109 percent efficiency, a SCOP of 0.99 to 1.09.[1]Daikin UK, How does a heat pump work? These are one manufacturer’s figures.
The other big difference is temperature. Daikin says air source systems deliver steady, low-temperature warmth over longer periods rather than short bursts of high heat, which suits homes with good insulation and modern radiators or underfloor heating.[2]Daikin UK, Air source heating explained It also notes that traditional radiators are typically smaller and designed for higher flow temperatures, so radiator upgrades may be recommended.[2]Daikin UK, Air source heating explained See flow temperature.
Side by side
| Gas boiler | Air source heat pump | |
|---|---|---|
| Energy used | Gas | Electricity |
| Efficiency | 99 to 109 percent, Daikin says | SCOP of 3 to 4, Daikin says |
| Heat delivered | Higher flow temperature, shorter bursts | Lower flow temperature, steadier |
| Boiler Upgrade Scheme grant | Not covered | £7,500 |
| Who can fit it | Gas Safe registered engineer | MCS certified installer for the grant, F gas qualified |
The efficiency figures come from Daikin.[1]Daikin UK, How does a heat pump work? The grant row comes from GOV.UK, which says the grant covers replacing fossil fuel systems with a heat pump or biomass boiler and is applied for by an MCS certified installer.[3]GOV.UK, Apply for the Boiler Upgrade Scheme Anyone employed to work on gas appliances in a home must be Gas Safe registered and competent for the type of work.[4]Health and Safety Executive, Domestic gas: frequently asked questions Refrigerant work on a heat pump needs a person with their own F gas qualification.[7]GOV.UK, Qualifications to work with F gas See MCS certification.
Example
Chris and Dani own a 1970s semi in Shipley with a 14-year-old gas boiler. They ask BASI for both options. BASI says that if a survey shows a gas boiler is the better fit, it will quote that alongside the heat pump and not push the heat pump regardless, and it lists new boiler installation from £1,695.[6]BASI Heating, Air source heat pumps, grant applied for you For the heat pump, the £7,500 grant comes off the invoice.[3]GOV.UK, Apply for the Boiler Upgrade Scheme Daikin says a poorly insulated home forces the heat pump to work harder and that a qualified person should carry out a heat loss calculation first.[5]Daikin UK, Types of Heat Pumps: Which One Is Right for Your Home? Chris and Dani book the survey and compare quotes for the heat pump and the new boiler.
What people get wrong
The most common error is comparing the headline efficiency alone. A SCOP of 4 is a seasonal average under test conditions. It falls in colder weather and at higher flow temperatures, and a boiler’s figure does not depend on the house in the same way.
Another is assuming a hybrid keeps the grant. The scheme says you cannot get a grant for a hybrid system.[3]GOV.UK, Apply for the Boiler Upgrade Scheme See hybrid heat pump. Running costs are a third. They depend on the gas and electricity prices at the time and on how well the home holds heat, so ask for the comparison in writing and read are heat pumps worth it.
The bottom line
A boiler makes heat from gas. A heat pump moves heat using electricity and delivers three to four units for every one it uses, at a lower flow temperature. A heat pump suits a well-insulated home and attracts a £7,500 grant if it replaces a fossil fuel system. A survey that prices both is the way to find out which suits your house.
Common questions
Is a heat pump cheaper to run than a gas boiler?
It depends on energy prices and the home. Daikin says a heat pump uses 3 to 4 kWh of heat per 1 kWh of electricity and describes air source running costs as broadly comparable with a modern gas boiler at current prices. Ask for a quote that compares both.
Do I need to change my radiators for a heat pump?
Sometimes. Daikin says traditional radiators are designed for higher flow temperatures and radiator upgrades may be recommended in some properties. A survey and heat loss calculation will show whether yours are large enough.
Can I get a grant for a new gas boiler?
The Boiler Upgrade Scheme only covers replacing fossil fuel systems with a heat pump or biomass boiler. It pays £7,500 towards an air source heat pump. It does not pay for a new gas boiler or for a hybrid system.
Which needs more space?
A heat pump needs an outdoor unit and, for an air-to-water system, usually a hot water tank. Daikin says an air-to-water installation typically needs an outdoor unit plus a hydraulic module, a hot water tank and circulation components.
Sources
We cite the original source for every figure: government, regulators, standards bodies and manufacturers' own documents. Each one shows the date we last checked it.
- Daikin UK. How does a heat pump work?. Checked 11 November 2026. ↩
- Daikin UK. Air source heating explained. Checked 11 November 2026. ↩
- GOV.UK. Apply for the Boiler Upgrade Scheme. Checked 11 November 2026. ↩
- Health and Safety Executive. Domestic gas: frequently asked questions. Checked 11 November 2026. ↩
- Daikin UK. Types of Heat Pumps: Which One Is Right for Your Home?. Checked 11 November 2026. ↩
- BASI Heating. Air source heat pumps, grant applied for you. Checked 11 November 2026. ↩
- GOV.UK. Qualifications to work with F gas. Checked 11 November 2026. ↩