Pool and Spa
Questions about Pool Repair? Ask an Expert Online.
Do this test....Turn off breaker and remove filters from the spa completely, turn on breaker and see if the FLO goes out, if so the filter can be just dirty enough to cause the flow switch to open and cut out power to heater. You can not see the dirt on filter as it may be organic. The other issue I have seen is a clogged circulation pump, the impeller in the pump gets clogged with debris and does nt push enough water through the heater and flow switch.