Heater shows E20 and will not fire when controlled by an external system.

Safety: Turn off power to heater and automation before working on low-voltage circuits.

• Check remote mode setting: On the heater control, verify that it is configured for remote operation if being controlled by automation. If not using remote, set it to local mode.
• Inspect fireman’s switch/remote terminals: Ensure the jumper is installed if no external thermostat is used. If automation is connected, verify proper wiring to the correct terminals.
• Test remote circuit: With a multimeter, check continuity across the remote thermostat wires when the external system is calling for heat. Repair or replace faulty wiring or relays.
• Operate locally: Temporarily bypass the remote by installing the factory jumper and test heater operation from the local control. If it works locally, the issue is with the external control or wiring.