No hot water: what to check before you call

Heat pumps normally heat water at lower temperatures than a traditional boiler. A heat-pump cylinder usually has a larger heat-exchanger coil so it can transfer enough heat into the stored water at those lower temperatures.

Start with the controls and schedules. Your installer should explain how thermostatic radiator valves, room thermostats and weather compensation interact in your particular design.

Some systems use an immersion heater for backup or hot-water hygiene cycles. Do not disable it permanently without understanding the control strategy.

A heat pump stops during a power cut because its compressor, pumps and controls need electricity. Once power returns, most systems restart automatically.

Before you call, record model numbers and settings and any code on the display. Leave covers, wiring and internal checks to an engineer.

If the cylinder is not keeping up, ask your installer whether it can meet your hot-water demand without forcing the heat pump to run hotter or for much longer than necessary, and what the expected hot-water recovery time is.