How to Fix / Troubleshooting

Safety first: Turn off power to both the heater and automation system before changing wiring.

Step-by-step checks:

Confirm control mode: Set the Pahlen heater to the correct external control mode per the installation manual.
Verify wiring type: Ensure the automation is providing the type of signal the heater expects (usually a dry contact closure). Do not feed external voltage into low-voltage terminals unless specified.
Check setpoints: Make sure the automation's desired temperature is higher than the current water temperature and that the heater's internal limit is not set lower.
Bypass test: Temporarily jumper the external control terminals at the heater to simulate a call for heat. If the heater fires, the issue is in the automation wiring or programming.

When to stop: If you are unsure about control wiring, consult a pool automation specialist or Pahlen technician.

Heater will not fire when controlled by pool automation, but works in manual mode.

Possible Causes