Pool and Spa
Questions about Pool Repair? Ask an Expert Online.
When you say heat sensor which piece do you mean? Basically if you can touch a wire and get it to work the connections are not tight enough. Pull the wires off the board from the flow switch and verify that they are clean and making a tight connection to board. If all this fails and you know the pump that supplies water through the heater is running good and HAS good water flow through heater then we have to look at the circuit board being bad. Also be sure that you have the flow switch in the proper direction if it is backwards then it will not work there is a small arrow on the lower grey part of the switch indicating direction of water flow.
If you have no water from pump to heater you will not heat. You need to determine if the pump is bad or just an air pocket in the pump with spa running loosen the union on front of pump to release any air and let water leak out for 10-20 seconds then re tighten. If that does not work replace the pump that feeds water through heater.