What happens to a heat pump in a power cut?
Short answer
A heat pump stops during a power cut because its compressor, pumps and controls need electricity. A modern gas boiler usually stops too for the same reason. Once power returns, most systems restart automatically. Some heat pumps also have electric backup heating, but that backup still cannot work while the whole property has lost mains power.
Last checked 24 September 2026 · 1 source
Does a gas boiler keep working in a blackout?
Usually not.
Modern gas boilers need electricity for ignition, pumps, fans and controls. Losing mains power therefore normally stops both a gas boiler and a heat pump.
That is the useful comparison from the source interview.
Will my home get cold immediately?
No. Buildings retain heat for a period after the heating stops.
How long the home stays comfortable depends on outdoor temperature, insulation, thermal mass, draughts and how warm the home was before the outage.
The source interview says most UK outages are short, but it does not provide a robust source for the claim that they are generally an hour or less. We would not publish that figure as fact without network data.
What does “backup heater” mean?
Some heat pumps include or work with an electric resistance heater for unusually high demand, faults or hot-water functions.
That can provide backup if the heat pump itself cannot deliver enough heat, but it still needs electricity. It is not a backup for a whole-house power cut.
Can a home battery run a heat pump in a blackout?
Sometimes, but only if the battery and inverter are designed for backup operation and can supply the required load.
Many battery systems do not power the whole house during an outage by default. Heat-pump starting loads and sustained output also need to be considered.
What should I do next?
If power cuts are a concern, ask your installer or electrician whether your battery, inverter or backup circuit can support the heat pump. Do not assume a battery provides whole-home backup just because one is installed.
Sources
- Source interview with Heat Geek installer, power-cut discussion.
Last checked: 24 September 2026