BoilerTroubleshooting2026-02-26
Heating Not Working but Hot Water Is
Heat off while hot water works points to a stuck diverter valve or thermostat/pump fault.
When your combi gives hot water but no heating, the heating side has a specific fault.
Common causes
A stuck diverter valve keeping the boiler in hot-water mode, a thermostat fault, a failed pump, or trapped air can stop heating.
What to do
Check the thermostat and pressure first; a stuck diverter valve or pump needs a technician.
Key takeaways
- Check thermostat and pressure
- A stuck diverter valve is common
- A failed pump stops heating
- Bleed radiators to clear air
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