Heater display is on but unit does not respond to a call for heat from the pool automation system.

Safety first: Turn off power before changing any low-voltage wiring.

• Switch to local control: Put the Thermeau heater into local/manual mode (if available) and set a temperature above current water temp. If the heater starts, the issue is with external control.
• Check automation settings: Verify that the pool controller is configured to enable the heater and that the desired body (pool/spa) is active.
• Inspect control wiring: At the heater, confirm that the external control wires are connected to the correct Thermeau terminals and that the cable is intact.
• Test contact closure: With a multimeter, verify that the automation provides a proper dry contact closure when heat is requested.
• Correct wiring or replace cable: Fix any miswiring and replace damaged control cable as needed.