S.30 — No heating demand from external controls

What does S.30 mean?

The boiler is not receiving a signal to provide heating from your external thermostat or control unit. This means the connection at terminals 3-4 is open, indicating no request for heat.

• External controls (thermostat) are off or incorrectly set.
• Wiring issue at clamp 3-4.
• External control unit is not calling for heat.

Click steps to track your progress.

1. 1

   Check your external room thermostat and ensure it is set to call for heat.

2. 2

   Verify any external control units are switched on and programmed correctly.

3. 3

   If no external controls are fitted, ensure terminals 3 and 4 on the boiler are linked (a qualified person should check this).