Snake Experts! Rack system heating questions/problem...

I actually am just copy/pasting this post that I made to a snake forum this morning. I know Chaz is a dog forum, but I do know there are some snake people here that may also have some insight for me.

That, and nobody has commented on the snake forum yet. LOL!

ETA: This is for cornsnakes, BTW.

...

Okay, so I built a rack over the weekend (which I swear I will post photos of soon... I just didn't have a chance to do that yet), but I am having a slight heating issue. I'm embarrassed. I feel like I should be able to figure this out, but I really don't understand how this problem is happening.


With the t-stat probe directly on the heat source, is it normal for the tubs to read at a higher temp than what the probe reads on the UTH?


Whole (long) story, with more questions at the end:

I put everything together Saturday and tested it with the t-stat probe (Herpstat ND) INSIDE one of the tubs. Everything ran perfectly, keeping my three tubs right around 85*F (all three were within 1*F of each other). Excellent! I get everybody set up, took some photos on we were on our way.

Yesterday (Sunday) evening, I go to feed, and realize my error with putting the probe inside the tub... while that snake is off the rack for feeding, the UTH (Ultratherm 11x11") is unregulated. Oops.

So I pull everybody out of the rack, remove the probe and stick it down directly onto the UTH on the rack shelf. Problem solved, right? Not really. All of a sudden, my tubs were reading as high as 94*F despite the fact that the t-stat was still set for 85*F.

I have a thermometer probe right next to the t-stat probe, and both are reading the same, while the tubs are still reading high. I got it to stabilize with the t-stat set to 80*, which is holding the tubs just under 86*F.


About the rack:

I constructed it from melamine. It's a verrrry simple four-shelf design. Each shelf can hold two 15qt Sterilite tubs. Only the top two shelves are occupied (two snakes on the top shelf, one snake and one empty tub on the second shelf). In the direct center of each occupied shelf is a 11x11" Ultratherm UTH (two in total, both identical). Both UTHs are on the same Herpstat ND t-stat. The probe is currently attached to the UTH on the top shelf. I have a thermometer probes WITH the t-stat probe, and in the warm side of each tub.



Now, I realize that the t-stat probe and the tub thermometer are going to read a little differently just because they are not in identical locations anymore. However, it seems really, really strange to me that the tubs would end up being warmer than the direct source. Especially with that wide a margin. I would think that the tubs would be slightly cooler than the direct source...


So...

Is this normal?
Is there something I'm not taking into account here?
Is there a better location/way to place the t-stat probe in this rack system?
Is there some other huge mistake that I'm making here???



I'm sorry this post is so long, I just wanted to make sure I included as many details as possible. I was so proud of my handiwork Saturday and now Sunday into this morning I am somewhat frustrated and pretty embarrassed by it. I just hope I haven't done something so terribly wrong that all the work I've done is now junk.


Thanks in advance for the help and any insight! :hail:

I've never done a rack system but Chewbecca has, hopefully she'll chime in! Most rack systems use heat tape, what are you using as a uth?

This is what I have.
Ultratherm Undertank Heater (UTH) - 11"x11" - Reptile Basics Inc

I know it says in the info that it doesn't need a thermostat , but I use one anyways.



I was using both of these UTHs (with a t-stat) prior to setting up the rack, and they worked just fine. I'd tested the t-stat, too, AND I have separate thermometer probes double-checking everything.

And it's still way off. I cannot for the life of me figure out why. The t-stat probe and the back-up thermometer directly on the UTH both read 80*F, but the tubs keep trying to push 90*F. This makes NO sense to me!

How many viv's are you doing?

Three 15qt Sterilite tubs, two UTHs. Each tub rests on half a UTH (so the top shelf shares one).

The two UTHs together are still waaaaaaaaaaaay below the wattage rating for the t-stat.

And again, I had these two running previously with no issues. The only thing that has changed is the location of the t-stat probe and the shelf they are sitting on.




There is a third UTH running under Reggie's 20L, but it has it's own t-stat. Which is why I haven't mentioned it.