I bought an older H100ID 100K BTU pool heater with issues. Current issue is that is blows the 20A GFCI when it turns on. Facts/things I have done: bypassed water psi sw (tested bad), tested low and hi temp sw(good), tested air psi sw(good), tested/bypassed interlock and thermostat, removed control board and soldered input pins that had cracked joints, removed/cleaned ignitor, checked voltage at gas valve(120vac). Plan on running power from a non-GFCI breaker to test breaker (1.5hp pool pump and aquatrol generator are on same circuit) but I am this side of positive it will do no good. Any help is appreciated, thanks

rusty