Air source heat pumps: what they are and how they work

Air source heat pumps (ASHPs) are an energy-efficient way to heat your home and hot water using the ambient air outside. By extracting heat from the air, even at low temperatures, these systems can reduce your energy bills and lower your carbon footprint.

In this guide, we’ll explain how air source heat pumps work, what types are available, the benefits and drawbacks, and what to consider before installing one in your home.

How air source heat pumps work

An air source heat pump absorbs heat from the outside air and transfers it into your home using a refrigeration process. Even when temperatures drop as low as -15°C, the pump can still draw heat from the air.

The system works much like a refrigerator in reverse. It pulls in outside air through a fan, passes it over a refrigerant, which absorbs the heat, and compresses the gas to raise its temperature. This heat is then transferred to your home’s heating and hot water systems.

There are two main types of air source heat pumps:

• Air-to-water heat pumps: These transfer heat to a wet central heating system. They work best with underfloor heating or large radiators, which can deliver heat at lower temperatures more efficiently.
• Air-to-air heat pumps: These produce warm air that is circulated around the home using fans. They cannot provide hot water and are less common in the UK.

Benefits of air source heat pumps

• Lower energy bills: If you’re switching from conventional electric heating or oil, you could save significantly on your annual energy costs.
• Lower carbon emissions: ASHPs produce fewer emissions than traditional fossil fuel heating systems, especially when powered by renewable electricity.
• Minimal maintenance: Once installed, they require relatively little upkeep. Regular checks and occasional servicing keep them running efficiently.
• Efficient all year round: Modern ASHPs work effectively even in cold weather and can be used for cooling in summer, depending on the system.

Potential drawbacks

• Upfront cost: Installation can be expensive. Depending on the size and complexity, costs typically range between £7,000 and £13,000 for an air-to-water system.
• Lower heat output: Heat pumps operate at lower temperatures than gas or oil boilers, so your home may need insulation upgrades or larger radiators.
• Space required: You need outdoor space for the unit and sufficient airflow around it. Some noise is generated by the fan, so placement matters.

Is an air source heat pump right for your home?

Before installing an air source heat pump, it’s important to assess your home’s suitability:

• Insulation: A well-insulated home helps get the most from your heat pump. Consider upgrading loft and wall insulation before installation.
• Radiators or underfloor heating: Heat pumps work best with larger radiators or underfloor systems. Existing radiators may need to be replaced or upgraded.
• Heating habits: These systems work more effectively when maintaining a consistent indoor temperature rather than being turned on and off frequently.

Installation and running costs

Installation prices vary depending on system type, property size, and any additional work required. Running costs will depend on your current energy source and usage habits, but in many cases, households can see savings, particularly if replacing electric, LPG, or oil heating.

You may also be eligible for financial support through government schemes such as the Boiler Upgrade Scheme in England and Wales, which offers grants for low-carbon heating technologies, including air source heat pumps.

Conclusion

Air source heat pumps offer a sustainable and efficient alternative to traditional heating systems. They’re especially effective in well-insulated homes and can significantly reduce your reliance on fossil fuels. While the initial investment is considerable, long-term savings and environmental benefits make them an increasingly popular choice for homeowners looking to future-proof their heating.

Find a trusted installer

If you’re considering installing an air source heat pump, speaking with a qualified installer and getting a property assessment is the best place to start.

Working with iheat we find you the best deals for a new heat pump. Get a new heat pump quote today.