Ever see a pot of boiling water give a reading of -55F? I have...

Ok, here's the scoop....
I have a Love Controller 4C Series, connected to a thermocouple in my RIM system. I had to have the controller replaced due to defective terminals but since then, the new one has worked fine. I have the controller hooked up to a 12 DC solid state relay and then going to a 1500w AC heating element (AC power is supplied separately). All of that works just fine.
The problem is, I hooked up my controller in the kitchen yesterday to the thermocouple, then dipped it in a pot of boiling water. Prior to putting the thermocouple in the water, the temp reading was 75, once I dipped it in the boiling water, it jumped down to 0 then to -55F.
I went through the programming with a Dwyer tech. on the phone a few weeks back when I initially programmed it so I know its set to F vs C and its programmed for the right thermocouple.
Has anyone ever seen this before or have any insight to what the problem might be?? I know all I need to do is wait til I Monday to call Dywer but this is my last step in a 7 month RIMS building project and I haven't been able to brew since Nov! Plus school is getting in the way. Any thoughts are welcome!!!


-Shawn "Puffy" Combes

Proper polarity.

Puffy84 said:

...I went through the programming with a Dwyer tech. on the phone a few weeks back when I initially programmed it so I know its set to F vs C and its programmed for the right thermocouple...

Click to expand...

I am guessing that you might have the wronge type of sensor (NTC vs PTC) But you said that it was programmed for the correct one so that has stumped me, unless the sensor was labeld/packaged wrong from factory?
Disregard this if you have thermocouples

I dropped a RTD temperature probe from Auber and got some strange readings like this. Turned out when I dropped it, the impact broke the sensor's thermal mass (looks like a piece of ceramic). This is part of the actual sensor inside the SS thermowell. I called Auber, they sent me a new sensor for $10 shipped. I soldered it in and was up and running again. If your probe is in a SS thermowell and you dropped it or knocked it hard against something, you may have done the same.

Issues like this have always been a loose wire or grounding for me.

Sounds like polarity or grounding troubles to me. I have had this trouble/accident when connecting TC to a controller that will accept TC or RTD sensor inputs. What seems like the proper polarity connection, actually is actually the proper polarity if you were connecting a RTD which is incorrect for a TC , if that makes sense.

if you connect a T/C backwards it will read backwards.

on most T/C's the red lead is the - lead.

I would reverse the T/C leads and try the test again.