FLO
Wellis Flow Switch Open / Insufficient Flow

Display shows FLO or FL1, heater disabled, pumps may still run

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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

Dirty filters restricting flow, Air lock after refill, Stuck or failed flow switch, Weak circulation pump

How to Fix / Troubleshooting

Safety first: Turn off power at the breaker before opening the equipment bay or loosening unions.

  • 1. Clean or remove filters:
    • Take out filter cartridges and rinse thoroughly.
    • Run the spa briefly without filters to see if FLO clears (do not leave filters out long-term).
  • 2. Bleed air from system:
    • Loosen the union on the circulation pump until air and water escape, then retighten.
    • Repeat on heater unions if necessary.
  • 3. Locate flow switch:
    • Find the flow or pressure switch in the plumbing near the heater.
    • Check that the arrow on the body aligns with water flow direction.
  • 4. Inspect wiring:
    • Ensure the flow switch cable is firmly connected to the control board.
  • 5. Test switch (qualified person):
    • With pump running, a technician can test continuity across the flow switch terminals.
    • If the switch remains open with good flow, replace the flow switch.
  • 6. If FLO persists with new switch and clean filters: The circulation pump may be underperforming or the control board input faulty. Have a spa technician evaluate.
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Repair Difficulty

Medium 3/5

Required Part

Flow Switch
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