Instant Impact of a Mains Failure
An air source heat pump relies on electricity for its compressor, circulation pumps and control boards. When grid power drops, the unit shuts down automatically to protect electronics. Heating and hot-water delivery stop, but the system retains water within pipes; radiators or underfloor circuits cool gradually over one to two hours.
Automatic Restart Sequence
Once power returns the controller performs a self-check, reinitialises sensors and—after a brief anti-short-cycle delay—ramps the compressor. Homeowners rarely need to intervene; the heat pump resumes its programmed schedule and set-point temperatures.
Potential Issues After Extended Outages
- Defrost Residue – Ice may accumulate on the outdoor coil if the outage coincides with severe frost. A post-restart defrost clears this within minutes.
- Clock Drift – Some controllers lose time settings, affecting weather compensation curves; a quick check on the interface corrects this.
- Buffer Temperature Drop – Cylinders or buffers may fall below hygiene set-points, triggering an automatic pasteurisation cycle that momentarily boosts electricity use.
Resilience Strategies
- Grid-Feed Battery Storage – A modest 5 kWh battery keeps circulation pumps and electronics alive for several hours, preventing lubricant migration in the compressor and maintaining low-level space heating.
- PV-Battery Coupling – Solar generation during daylight can charge the battery, extending runtime in rural areas prone to long outages.
- Hybrid Backup Heater – Retaining a small immersion element or existing boiler provides hot water during prolonged blackouts; controls can switch automatically when the heat pump is offline.
Maintenance Best Practice
Regular servicing ensures capacitors, relays and surge-protection modules remain in good order. Air To Heat engineers verify that firmware supports automatic restart and logs power-cut events, helping diagnose rare failures.
Key Takeaways
- Heat pumps shut down safely during outages and auto-restart once power returns.
- Short cuts pose minimal comfort issues; longer cuts can be mitigated with batteries or hybrid elements.
- Annual service checks confirm restart functionality and controller time accuracy.
For tailored advice on backup solutions, call us on 0208 936 7639 or reach out online to speak with an MCS-qualified engineer.
