I have a 1995 Hot Spring Highlife (K-151031). I can't get the water to temperature between 92 and 104. It would stay at 92 and I would move the thermostat up just a bit, and did that several times, but with no change in temperature. I removed the filters just to eliminate them as a variable. As I went from 1 up to about 7 or so, the first temperature change I got went all the way to 104. I have moved the thermostat down a notch at a time, but the water is still 104. I can hear the thermostat click near the extreme low and high range of the dial, but I can also hear it click somewhat erratically when I first push it in to turn it when it has been sitting at various positions on the dial. The thermistors were replaced around February or March, when the heater was replaced. The thermostat checked out good at that time, but the hot tub has been rarely used since then because of a leak in the shell that I recently fixed. I hate to start throwing parts at it until I can get an educated opinion of what the problem is.

It could be the thermostat itself, the heater relay, or a loose connection anywhere in between. If the relay is behaving, I'd suggest a whole new topside control rather than replacing the thermostat alone.

What would be the process of checking the relay? What is a good source for the topside control?

http://www.backyardplus.com/ carries most Hot Springs parts and may be able to send you a wiring diagram so you can see which relay the thermostat is on. A relay works by sending voltage across a coil which in turn closes a circuit. In this case, your thermostat is sending voltage across the relay coil to close the heater circuit. The coil may be 120v or 240v. When it has the proper voltage across it, it should be closed. No power = open.

It sounds like the thermostat is bad...when they click erratically in a bunch of positions on the dial they are no good.

Thanks for the help. The new thermostat solved the problem.