We have a 2004 Cal Spa with a CS5300 control board and the heater will not turn on. When I turn the tub on I get numbers 00, 11, 00, 100, 51 (current temp). The LED light is NOT on. I installed a new heater element and it is getting voltage (is the element always powered and the ohms is what turns on the heater?), pump is OK, pressure switch being adjusted did not help, checked the thermostat, the temperature reads 51 degrees, there is plenty of flow, the valves are open, filters are not clogged, there are no air locks. Does anyone have any suggestions on something else I need to try? Thanks for reading!

If you have Voltage to the Element and it is not Heating, Element is open. Flow switch will stop Element from heating if bad or needs adjusting. Should be open with no flow, and closed with flow. If you clamp an ampmeter around heater wire and it show no draw with voltage, Element IS open. Good Luck