Pentair Extended Post-Purge / Blower Run-On

Heater fan or blower continues to run for a long time after the burner shuts off.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Normal post-purge cycle, Stuck blower relay on control board, Faulty temperature or flue sensor keeping blower on, Control board logic fault

How to Fix / Troubleshooting

Safety: If the blower runs continuously and will not stop, turn off power at the breaker.

  • Determine if behavior is normal: Many Pentair heaters run the blower for a short post-purge period (typically a few minutes) after burner shutdown. This is normal.
  • Check duration: If the blower runs indefinitely, inspect the control board for a stuck blower relay or signs of damage.
  • Sensor check: A flue or temperature sensor reading high may keep the blower running. Verify sensor readings and replace faulty sensors.
  • Replace control board: If the relay is stuck or logic is faulty, replace the main control board.
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Repair Difficulty

Medium 3/5

Required Part

Blower Relay on Main Control Board
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