I filled my tub up today after replacing some bad check valves. Now the gfci trips within 10 -15 seconds of power up. I tested the heater circuit again. There are 0 volts with the jets running (110 volt spa ), 114 volts with the thermostat engaged ,and 0 volts with the thermostat disengaged. The heater housing gets really warm to the touch but you can barely hear any water running at all through the plumbing. I disconnected the heater leads and taped them off well and powered the spa back up with the same result, a tripped gfci in just a few seconds.
Could my circ pump be weak enough that it is causing the gfci to trip?
Thanks

Bummer, was hoping you'd be in Hot Water by now! Probably the circ pump... does the spa have an ozone generator? Try unplugging the circ pump, and see if the problem goes away... I suspect the circ pump may be having more issues than current leakage... if the heating element is getting warm to the touch... it should remain approx the same temp as the water (approx 4 F warmer).. So, you may just be killing two birds with one stone by replacing it " title="Wink" /> Just to clarify, you removed both leads from the heater while testing?

I replaced the circ pump yesterday morning after unplugging it and finding the breaker did not trip. After a couple of check valves and a circ pump I was finally able to soak in hot water last night " title="Very Happy" /> (Saturday). Swine, thanks for all the advice.