Control indicates E10, burner stops, and the display may show a symbol for external thermostat or safety loop.

Safety: Disconnect power. Do not bypass safety devices permanently; they protect against dangerous conditions.

• Trace safety loop: Using the Viadrus wiring diagram, identify all devices in the safety chain (e.g., flue gas thermostat, system high‑limit, low‑water cutoff). Check each for continuity with a multimeter.
• Reset flue thermostat: Some Viadrus installations include a manual reset flue gas thermostat on the flue hood. Once cooled, press the reset button until it clicks. Investigate why it tripped (e.g., blocked flue).
• Check room thermostat: Verify that the room thermostat or external controller is calling for heat. Replace batteries if wireless. Check that the thermostat contacts close when calling for heat.
• Inspect wiring: Look for loose connections or broken wires in the low‑voltage thermostat cable between the furnace and the room thermostat or safety devices. Repair or replace as needed.