Do Air Source Heat Pumps Work in Cold Weather?
Modern air source heat pumps, or ASHPs, can extract heat down to roughly 15°C, although their efficiency may be reduced at extremely low temperatures. During our typical UK winters, going for extended periods below -5°C is rare, so homes that are relatively well insulated can maintain substantial comfort without supplemental heating.
That said, there are always exceptions, and deep cold snaps combined with high heat demand or excessive heat loss can slow recovery after setbacks. This means that, depending on your unique needs and property, a backup heat source may be a worthwhile and prudent investment.
When ASHPs May Need Backup Heating
Here are a few situations where you may want to give significant consideration to installing a backup heating system with your ASHP:
- Properties that are regularly exposed to sub-zero temperatures for days or even weeks at a time.
- Large buildings, or those with poor insulation, will be hard for the average ASHP to handle alone.
- Settings or facilities with critical temperature needs, like medical facilities or care homes.
Implementing a Hybrid System
- Configure the ASHP controller to activate backup heating when the outdoor sensor falls below a set threshold, like 0 °C, for example.
- Integrate hydraulic separation or dedicated valves so that the ASHP and backup heat source can run independently or together without interference.
- Commission and test both systems in cold conditions to ensure smooth, automatic handover and maintain overall system efficiency.
Optimise Your Building’s Heating Without Over-Engineering
Use weather‑compensation controls to gradually raise flow temperature as outdoor conditions worsen, which can reduce your dependence on backup systems. Also, increase the insulating qualities of the building and balance the radiators to reduce additional heat demand.
Most homes in the UK won’t need constant backup heating, but a simple hybrid system can give homeowners insurance against extreme cold and high-demand scenarios. To get started designing the right system for your property, enquire online or call us on 0208 936 7639.
