Boiler does not respond to room thermostat or programmer

Safety first: Isolate power before working on control wiring. Wireless devices can usually be checked without isolation.

• Check thermostat batteries: Replace batteries in wireless thermostats and re-pair with the receiver if necessary.
• Verify programmer settings: Ensure heating channels are set to ON or timed correctly and that holiday or frost modes are not active.
• Check receiver indicators: On Remeha-compatible receivers, confirm that the call-for-heat indicator lights when the thermostat demands heat.
• Engineer tasks: Test continuity of control wiring, replace faulty receivers or thermostats, and confirm correct wiring at the boiler terminals.