Novy Posted May 26, 2014 Report Share Posted May 26, 2014 I'm trying to sort out an issues with a 95 Hot Springs Sovereign that my dad bought used about 5 years ago when he was living in my house and I was working away from home. In the first year it worked fine for about 3 months and started tripping the breaker instantly. The tub was drained and left because we were nearing winter and didn't want to be troubleshooting issues and risk freezing anything. The next year I noticed a loose ground wire, tightened that up and fill the tub to try it and again it worked fine for a while but eventually got to the point where the water was too hot, causing the power light to flash. Again, nearing winter the tub was drained and left. My dad moved out, I'm back home and have decided to try getting it working again. I filled it with water, and within a day the water temperature was up around 120 degrees with the power light flashing. I added cold water to bring it back down to around 100 so I could try the jets out and that worked fine. Within a few hours it was back to 120. The temperature control knob had no effect on the temperature, it always ends up around 120. I tested the control stat and high limit thermistors because those numbers were easy to find online and they both seem to function properly (reading about 4.5k ohms at 120 degrees). I need some guidance on what to test next. Quote Link to comment Share on other sites More sharing options...
PreservedSwine Posted May 28, 2014 Report Share Posted May 28, 2014 Either a stuck heater relay, or a bad thermistor. 4.5k sounds too high at 120F, but even so, turning it down would have turned off the heater. More than likely a stuck relay (12v dc coil t-92) Quote Link to comment Share on other sites More sharing options...
Novy Posted May 29, 2014 Author Report Share Posted May 29, 2014 From the chart's I've found they seem to indicate that at 120 the thermistors should be somewhere in the 3.5-4k range. I did a quick test, and the actual numbers were in the 4.3k range . Would such a small difference cause such substantial overheating? Is there a way one can test for a bad relay? When I got home from work this morning I noticed the light wasn't flashing so I took a look and the temperature and it was roughly 108. Then this afternoon it was flashing again, with the temperature up around 122. Hopefully this erratic behaviour might be of some use in diagnosis. Quote Link to comment Share on other sites More sharing options...
PreservedSwine Posted May 29, 2014 Report Share Posted May 29, 2014 The thermistor sounds slightly out of range for that temp, but that wouldn't cause this type of heating. Just meter out the relays (with the power off) and see if the heater relay has continuity through it without the coil being energized. If you'd like to guess, it's a pretty solid guess that's your issue. It's a T-92 relay (12volt dc coil) There are several inside the control box-all identical, ensure you're replacing the correct one. Quote Link to comment Share on other sites More sharing options...
Novy Posted May 30, 2014 Author Report Share Posted May 30, 2014 I'm not 100% sure I did this right, but with the tub breakers off and the heater connections removed from the relay I measured the resistance at those two terminals and the meter showed it to be open. Is that correct? Quote Link to comment Share on other sites More sharing options...
PreservedSwine Posted May 30, 2014 Report Share Posted May 30, 2014 Closed = no resistance, open is good, it means the relay is not stuck closed. Does it still overheat if you turn the temp all the way down? What does the thermistor read at ambient temp? Either a bad thermistor, or the elec t-stat has had it. Quote Link to comment Share on other sites More sharing options...
Novy Posted May 31, 2014 Author Report Share Posted May 31, 2014 Yes, the last few days I had the tub set as low as the dial would go without being off and it was still overheating. I've had the tub turned off for about 24 hours now and tested the thermistors. The thermistors should be more or less at the same temperature as the outside air being that there is no circulation. Our temp today was in the area of 77 degrees and I got readings of 8.6 on one and 8.7 on the other. We are supposed to get down to 50 over night so I can check again in the morning and see what they read. Quote Link to comment Share on other sites More sharing options...
PreservedSwine Posted May 31, 2014 Report Share Posted May 31, 2014 Thermistors are fine. Either a stuck relay, or bad elec t-stat. Quote Link to comment Share on other sites More sharing options...
Novy Posted May 31, 2014 Author Report Share Posted May 31, 2014 Any way to test a bad thermostat? Quote Link to comment Share on other sites More sharing options...
PreservedSwine Posted June 2, 2014 Report Share Posted June 2, 2014 You would need a reostat that could change resistance on the fly from 0.0 OHM to roughly 15-20K OHM, which I doubt you own. Are you 100% certain the relays are working properly? Quote Link to comment Share on other sites More sharing options...
Novy Posted June 3, 2014 Author Report Share Posted June 3, 2014 I decided to do some more extensive testing with the heater relay tonight using a car battery to power the coil. It is in fact sticking closed intermittently. Ordered a new one tonight, I've got my fingers crossed this gets the tub up and running 100%. I appreciate all your help. Quote Link to comment Share on other sites More sharing options...
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