I've got a used 1997 Hot Springs Classic Model F Spa. After working out some electical issues (thanks to Swine and Dan-the-spa-man of this forum) I've been enjoying it all year.

Recently the hi-limit switch has been tripping (as indicated by the blinking power light). I kill the power for 30 seconds and it works again for an hour or so, then trips again.

Symptoms:

The SilentFlo pump is working fine. When the heater is working, I can feel the hot water come from the bottom drain. I can also feel and hear the pump working.

When I recycle the power, the heater heats up quickly and becomes too hot to keep my fingers on it for more than about 5 seconds.

I'm suspecting the Hi-Limit sensor/switch is bad and I've ordered a replacement.

My questions are:

How can I tell which of the sensors is the hi-limit sensor? As I understand it, one is the thermostat and the other the hi-limit sensor, but I dont know which is which.

Do I have to drain the tub to replace the hi-limit sensor?

Finally, does anybody think it might be something else like a bad heater? I only ask because it does seem to be getting pretty hot which means the hi-limit switch is just doing its job. I hate the thought of replacing the heater...it looks like a bear to get to.

Thanks for any help.

Mark

T-stat thermistor is on the "in" side of the heater, and the high limit is on the "out" side of the heater. (water flow)



But it doesn't really matter, they utilize different thread sizes and different harness configurations. If you order a high limit, it's impossible to install it in the wrong spot or plug it into the wrong harness.

Good luck,

~Swine

[quote="wagermd"
When I recycle the power, the heater heats up quickly and becomes too hot to keep my fingers on it for more than about 5 seconds.

Do I have to drain the tub to replace the hi-limit sensor?

Finally, does anybody think it might be something else like a bad heater? I only ask because it does seem to be getting pretty hot which means the hi-limit switch is just doing its job. I hate the thought of replacing the heater...it looks like a bear to get to.

Mark[/quote]

Mark, all the hi-limit sensor does is tell the heater to shut off if the heater is getting too hot so it doesn't burn itself up...and once it does this the power light flashes.

If the tub is 220V the heater should feel warm to the touch but it should not be too hot to touch so shortly after resetting the power.

It still sounds to me that the silent-flo pump may not be pushing water through the heater fast enough.

1. Try taking the tub's filters out 1st
2. If that doesn't work there could be something in the impellar causing it to push less water
3.If it is the original pump then it is probably on it's last legs and needs to be replaced.

To replace the thermistors or the pump you can crimp-off the 3/4" lines with a few pairs of needle-nose vise grips instead of draining the tub.

Good luck!

Thanks again you guys! I removed the filters and reset the power. No thermal-trip yet and its been hours.

I've now ordered some replacement filters. I think that my old and dirty filters is all that was wrong.

Thanks again. You guys rock!

Mark