FLO
Caldera Spas
Insufficient Water Flow Through Heater / Flow Switch Open
Display shows “FLO” or “FLO2”; heater does not run and spa will not heat.
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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 or collapsed Caldera filter cartridge, Air lock in circulation system, Sticking or failed flow switch, Weak or failed E5 circulation pump
How to Fix / Troubleshooting
Safety first: Turn off power at the GFCI breaker before removing filters or opening unions.
- Clean or remove filter: Take out the filter cartridge and rinse thoroughly. For testing, run the spa briefly without the filter to see if the FLO code clears.
- Bleed air: Loosen the union at the circulation pump or heater until water flows steadily, then retighten to remove trapped air.
- Check circulation: Restore power and verify that you feel a steady stream at the circulation return jet. If there is no flow, the E5 circulation pump may be failing.
- Inspect flow switch: Locate the flow switch in the plumbing near the heater. Check that the wires are firmly connected and that the switch body is not cracked or leaking.
- Tap test: With power off, gently tap the flow switch body to free a stuck paddle, then restore power and see if the code clears.
- If still no improvement: Replace the flow switch with a Caldera-compatible unit. If the pump is noisy, hot, or not running, replace the E5 circulation pump.
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Repair Difficulty
Medium
3/5
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