2002 Sundance Optima 850 Hot Tub - Water not hot enough, but not cold.

[eluvins]

I have a Sundance Optima above ground Hot Tub, 850 series model that was purchased in 2002.  I recently cleaned, and installed a brand new filter and successfully enjoyed a few times prior to this current issue.  It appears the Hot Tub display "thinks" it's at the desired temperature, when it is not.  There are no error messages on the display. When the temperature is adjusted higher, the display shows the heater being activated and attempts to heat up.  When I stick my hand in the water, it feels about 30-40 degrees cooler than what the display reads.  I can feel some pockets of warm water.

I'm hoping the issue is with the thermostat, and not the heater, but I'm not certain.  Any direction or suggestions would be greatly appreciated.

Thanks,
Eric V.

[SerjicalStrike]

Sounds like a bad temperature sensor.  Fairly easy fix.

[Tman122]

Yea could be a couple different things. The heat light is on? Is the heater activating? Are you capable enough to use a voltage tester? Do you have a floating thermometer or a portable electronic temp sensor? My voltage tester has a probe for temperature reading.

First course of action would be to determine if the heater is on (powered) when it calls for heat. This will eliminate the temp sensor as the problem and steer to heater/other. I'm curious when you said the heat indicator was on. Seems the sensor has told it to heat and it's not? What temp is it currently at and set at? You should use a remote temp probe against the display set temp.

[eluvins]

The heat light is on? Yes, within display, heater comes on when I increase temp and turns off when it "thinks" it reaches the temp.

Is the heater activating? I believe so as the water is not cold (It was 30 degrees overnight here in MT)


I plan on checking the actual temp this evening after work, just to note the difference.  We typically set the temp to around 99 degrees F.  The display will read what it thinks is the current temperature: 99 degrees F.  When I increase to 103 degrees, the heater display kicks on and will turn off when it thinks it's reached it's desired temp.  When the heater is on and I insert my hand into the water, I can feel some warm pockets entering the hot tub.

I'm starting to believe (hope) its the sensor as it is the less expensive fix.

Thanks for your input!