No Central Heating but Hot Water OK — External control fault

What does No CH, HW OK mean?

The boiler provides hot water normally, but the central heating system does not turn on or heat up. This usually points to an issue outside the boiler itself.

• A fault with external controls such as the room thermostat
• Faulty central heating programmer
• Faulty zone valve that directs hot water to the radiators

Click steps to track your progress.

1. 1

   Check your room thermostat settings and ensure it's calling for a temperature higher than the current room temperature.

2. 2

   Verify your central heating programmer is correctly set to 'on' or 'auto' for heating periods.

3. 3

   If you have radiator thermostatic valves, ensure they are open and not stuck in the closed position.

4. 4

   If these checks don't resolve the issue, contact a qualified electrician or heating engineer to inspect external controls.