OF
Heat Siphon Unit in Off/Standby or External Control Lockout

Display shows “OF” or “OFF” and unit will not respond to heat commands.

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Possible Causes

Thermostat set to OFF, External automation (AquaLink, IntelliTouch, etc.) holding unit off, Internal enable/disable jumper misconfigured

How to Fix / Troubleshooting

Safety first: Ensure dry hands when operating controls.

  • Check mode: Verify the Heat Siphon control is set to HEAT or AUTO mode, not OFF.
  • External controls: If connected to pool automation, check the automation system’s heater enable setting and water temperature setpoint.
  • Internal enable: Some models have an internal enable/disable jumper or switch on the control board. Confirm it is in the ENABLE position per the installation manual.
  • Power cycle: Turn power off for 1–2 minutes, then back on and recheck operation.
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Repair Difficulty

Very Easy 1/5
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