How to Fix / Troubleshooting

Safety first: Turn off power before removing the thermostat from its base.

Check connections: Ensure all power and bus wires are firmly clamped in the thermostat base terminals.
Inspect supply source: Verify that the boiler or external transformer is correctly sized and not overloaded by additional devices.
Test with stable supply: If possible, temporarily power the thermostat from a known good low‑voltage source to see if flicker stops.
Replace thermostat: If supply is stable but flicker persists, the internal electronics may be failing and the thermostat should be replaced.

Thermostat backlight flickers or display intermittently dims.

Possible Causes