Strange Thermostat Behavior

[TheLateQuentin]

I have a 1 year old RayPak 336A.

When the heater is NOT heating, it reads the temperature correctly. When it starts heating, the temperature reading shoots way up, so it turns off.

For example, the real temperatures is 72 degrees. The heater reads 72 degrees. I set it to 85 degrees. The heater turns on and starts heating. Within seconds, the temperature reads 90 degrees and the heater turns off.

Any idea? TIA

 

[ajw22]

Welcome to TFP.

It is either a bad temperature sensor thermistor, bad control board, or a critter chewed on some wiring.

Get a 10K resistor and connect it in place of the temperature sensor. The heater should read 78 degrees.

If the heater works fine with the resistor then replace the sensor. If it still fails then examine the wiring. If the wiring looks good then replace the board.

 

[mknauss]

At 1 year old, this should be covered by warranty.

 

[TheLateQuentin]

mknauss - the problem is I can't get in touch with anyone! All of the warranty stations that are listed say they have nothing to do with RayPak maintenance services. It's aggravating.

Sorry to be dense. I believe the temperature sensor is #1 in the pic below?

 

[ajw22]

mknauss - the problem is I can't get in touch with anyone! All of the warranty stations that are listed say they have nothing to do with RayPak maintenance services. It's aggravating.

Sorry to be dense. I believe the temperature sensor is #1 in the pic below?
View attachment 335491

That is correct. I am diagnosing a similar problem on my Pentair MasterTemp.

This is the 10K resistor I rigged to two alligator clips.



Then I used two nails to connect it into the connector.