How to Fix / Troubleshooting

Safety: Turn off power and gas if the heater is firing unexpectedly.

Check remote wiring: Inspect the fireman’s switch or remote thermostat terminals for shorted wires or moisture bridging the contacts.
Test in local mode: Disconnect remote wiring and operate heater only from its local control. If unintended firing stops, the issue is in the external control or wiring.
Automation relay check: Have a technician inspect the automation system’s heater relay for sticking or welded contacts.
Control board replacement: If the heater still fires without a valid call for heat and remote wiring is removed, the main control board may be defective and require replacement.

Heater turns on even when there is no apparent call for heat from the pool or spa.

Possible Causes