Outdoor air
The outdoor unit draws air across a heat exchanger.
Air-source heat pumps
Could an air-source heat pump suit your property?
Air-source heat pumps collect low-level heat from the outside air and use it to provide space heating and, in many systems, hot water.
How it works
Turning outdoor air into useful heat
An air-source heat pump uses a refrigeration cycle to absorb heat from outside air, raise its temperature and transfer that heat into the property.
The system is designed to run steadily and efficiently, often at lower water temperatures than a traditional boiler.
Heat absorbed
Refrigerant collects low-level heat from the air.
Temperature raised
A compressor raises the refrigerant temperature.
Heat delivered
Heat is transferred into the home’s heating system.
Property suitability
What makes a property a good candidate?
Suitable outdoor space
The outdoor unit needs clear airflow, maintenance access and an appropriate position away from obstructions.
Manageable heat loss
The building should be assessed room by room so the system can be sized for the actual heating demand.
Compatible heat emitters
Radiators or underfloor heating must be able to deliver enough heat at the proposed flow temperature.
Hot-water space
Many systems use a compatible hot-water cylinder, so internal cupboard or plant space may be needed.
Insulation can affect both comfort and system size.
Improving loft, wall, floor or draught performance may reduce heat demand, but recommendations should be based on the actual building.
Benefits and considerations
What should you weigh up?
Potential benefits
- Can provide both space heating and hot water.
- Uses electricity to move heat rather than generate all heat directly.
- Can reduce reliance on oil, LPG or gas heating.
- Often simpler to install than a ground-source system.
- Can work well with correctly sized radiators or underfloor heating.
Things to consider
- The outdoor unit needs a suitable location and airflow.
- Some radiators or pipework may need upgrading.
- Running performance depends heavily on design and controls.
- A hot-water cylinder may be needed.
- Installation cost varies significantly by property.
System design
What a good quotation should explain
Heat-loss calculation
The quotation should be based on room-by-room heating demand rather than a rough floor-area estimate.
Heat-pump output
The proposed unit should be matched to the property’s design conditions and expected operating temperatures.
Radiator changes
Any replacement or additional radiators should be listed clearly in the scope of work.
Hot-water arrangement
The cylinder size, heating method and expected recovery should be explained.
Electrical work
The quotation should identify any consumer-unit, supply or dedicated-circuit work.
Controls and commissioning
You should understand how the controls work and what settings will be used when the system is commissioned.
Installation journey
What happens before installation?
A proper assessment should happen before you agree to the final system. The installer should explain the design, required building work, likely disruption and what is included in the price.
- Initial enquiry Provide information about the property, current heating, energy use and preferred timeframe.
- Property assessment The installer checks heat loss, radiators, hot water, outdoor location and electrical requirements.
- System design and quotation You receive a written proposal describing the equipment, work, price and expected installation process.
- Review and agreement Compare the scope, warranties, exclusions and payment terms before deciding whether to proceed.
- Installation and handover The system is installed, commissioned and explained, with relevant documents and warranties provided.
Common questions
Air-source heat pump FAQs
Can an air-source heat pump work with existing radiators?
Sometimes. The installer should calculate the heat output needed in each room and check whether the existing radiators can provide it at the proposed water temperature.
Will I need a hot-water cylinder?
Many air-to-water systems use a compatible hot-water cylinder. The required size and location depend on household demand and the system design.
Does the heat pump work in cold weather?
Air-source heat pumps are designed to operate in cold outdoor conditions, but output and efficiency vary with temperature and system design.
How long does installation take?
Timescales vary depending on the property and the amount of radiator, pipework, electrical or cylinder work required.
How noisy is the outdoor unit?
Noise varies by product, operating conditions and installation position. The installer should assess the proposed location carefully.
Next step
Request an air-source heat pump assessment
Tell us about your property and current heating system. An installer or adviser can then contact you to discuss suitability and next steps.