This is a helpful fault to have, because it rules a great deal out: gas, ignition and the main heat exchanger are all clearly working.
On a combi boiler
The most likely culprit is the diverter valve, which redirects heated water to the taps when you turn one on. When it sticks in the heating position you get radiators but no hot water. A failed flow sensor or a scaled plate heat exchanger produces similar symptoms.
On a system or regular boiler with a cylinder
Check the programmer is calling for hot water and the cylinder thermostat is set above 60°C. If both are fine, suspect the hot water motorised valve or its actuator, or a failed immersion element on cylinders that rely on one.
What you can check safely
Before booking a visit:
- Confirm the hot water schedule on the programmer is actually on.
- Run a bath tap fully, as some faults only show at low flow.
- Check the boiler display for a fault code and note it down.
Booking a repair
Diverter valves and heat exchangers are sealed-appliance work. If you'd rather not tackle it yourself, we cover Birmingham and surrounding areas, seven days a week.
Want it done for you?
If you want your plumbing or heating problem fixed professionally for you, contact Matt Plumbing & Heating today for fast, reliable service across Birmingham and surrounding areas.
