Common causes of no hot water
- Boiler lockout — fault code on the display, often a pressure or ignition issue.
- Failed immersion heater element on a hot water cylinder.
- Frozen condensate pipe on a condensing boiler in cold weather.
- Failed motorised (zone) valve stopping hot water reaching the cylinder.
- Diverter valve failure in a combi boiler (heating works, hot water does not).
- Thermostat or programmer fault — heating-only systems most common.