Display shows SPFLO or FLO; heater will not fire even though pump is running

Note: Running the heater with low flow can damage the heat exchanger. Do not bypass flow safeties.

• Verify pump operation: Confirm the circulation pump is primed and running at the correct speed (for variable-speed pumps, use the heater-recommended RPM).
• Clean filter: Check the filter pressure gauge. If high, backwash or clean cartridges to restore normal flow.
• Check valves and bypass: Ensure all valves leading to and from the SmartPool heater are fully open and that any bypass valve is set per the heater manual.
• Inspect pressure/flow switch: With power off, locate the SmartPool flow or pressure switch on the water header. Check for loose wires and corrosion. Gently tap the switch body; sometimes a stuck diaphragm will free temporarily.
• Test restart: Restore power and call for heat. If SPFLO persists with good flow, the pressure/flow switch may need replacement.