Rack Temps

I have a CB70 rack from RBI, can anyone tell me why my temps in the top rack are always different from the middle and bottom one? For instance, right now my top hot side is 84 and cold is 79 while the bottom and middle are both at 89 hot and 84 cold?

I would have thought the top would have been the hottest. I have a Helix thermostat set at 94 and am using a Ranco as backup set at 96, I also have a temp probe set right next to the Helix probe and that reads 96 and for whatever reason even before I purchased the backup t-stat the digital temp gauge always read 1-2 degrees higher than what the Helix was set at.

All probes are taped directly to the heat tape just to the right of the top tub and temp were measured with a heat gun from inside the hides.

Any ideas?

ETA: I am using aspen as substrate and it is as evenly layed throughout the tubs as I could have got it, if that makes a difference.

The top tubs are warmer as heat rises.( Thats why I use a ceiling fan) There is either less heat cable than the lower tubs, or a bad flexwatt section. Look for a dead spot in the cable or flexwatt.

I checked the flexwatt with the temp gun and the hottest spot on the top 101, middle 106, and bottom was 110. Is this supposed to be like that? Am I measuring wrong? What I did notice was the middle and bottom rack have flexwatt lined on the side where the top is just lined on the bottom.

If your probes are on the heat tape directly then your flexwatt should not be reaching the 100 degree plus range because you only have your thermostat set to 94. Your heat tape should never get hotter than what you have your T-Stat set to. I would re-check your probe placement and make sure its taped down real well, you may also want to place your probe in the middle of your rack to help you get a more even temp spread among your tubs.

Put the probe on the center most section of the middle rack on the tape.

Thanks for all the replies so far, I appreciate the help.

Should I tape over the entire probe? Right now I just have the tip of the probe showing and if I tape the probe to the center won't I have problems with the tub rubbing it when I open and close it?

I would make sure you have the probe completely covered aginst the flexwatt with tape. You don't want it exposed to the air, only the flexwatt. I would personally not put it in the middle because like you said the tub could rub the probe off and then you could have cooked snakes. I have my probe off to the side on the heat tape and have no problems.

RBI has two little bars on top of their heat tape which is also lower than the shelf, so the tub does not come into contact with the flexwatt. I put mine directly in the middle with great results.

I completely covered the probe with tape and still my temp read over 100 on the flexwatt. Really not sure what else I can do. I really don't see what else I could be doing wrong.

Try one T-Stat at a time and see if you can isolate your problem to either of the Thermostats. If both thermostats on their own are having the same problem then I would think its the heat tape thats acting improperly.