Air source heat pumps… an absorbing proposition

Air source heat pumps absorb heat from the outside air. This heat can subsequently be used to warm radiators, air convectors and water, or in other heating systems. The process lowers fuel bills, cuts carbon emissions, and requires minimal maintenance.

The way it works is, ambient heat is absorbed at low temperatures into a fluid that passes through a compressor and generates higher-temperature heat, which is channelled through the heating circuit.

There are two main types of air source heat pump systems:

• Air-to-water: Heat is distributed via the wet central heating system. This approach is more efficient than standard boiler systems when lower-temperature hot water is required, which makes them particularly suitable for underfloor or walls heating systems, or larger radiators.
• Air-to-air: These systems produce warm air circulated by fans which is typically used to heat spaces.

When deciding on an air source heat pump, you need to consider:

• Space: Do you have somewhere to put it? It will need to be placed outside or inside, where there is enough space and a good flow of air, fitted to a wall or placed on the ground.
• Insulation: Is your building/office/home well insulated? Heat losses need to be minimised, so make sure your space has no draughts.
• Starting point: What fuel will you be replacing? The upgrade will pay for itself faster if it is replacing an inefficient electricity or coal-fired system. Switching from a gas-fired system may be less beneficial.
• Heating system: What type of heating system will you use? Air source heat pumps perform better with systems that require lower temperatures (e.g. underfloor or walls heating systems, warm air heating).
• Combination: Is the system intended for a new development? Combining the installation with other resource-efficient building work can reduce the overall cost of installation.

Tip

A well-maintained heat pump system can last 20 years (the lifetime fo the compressor is usually 15 years) and typically comes with a warranty that can be extended for an additional fee. Building owners/supervisors should monitor the pump’s performance, and request a professional check-up every three to five years (which will also depend on local regulations on electrical equipment).

Planning approval may be needed so check with the relevant authority before installing a heat pump system.