Help with heating rack

Hoping all you more experienced people could give me some ideas on how to better heat these racks I made. They are open on the sides and back and I've installed heat tape for belly heat but the bottom of the rack is only getting to around 80 degrees where the top is getting around 90. I think the 90 is ok (correct me if I'm wrong) but I need a way to get the bottom temps up without buying more thermostats.
It would be hard to close off the sides of the racks with the heat tape installed how it is.. I could put something over the back to cover it up but I'm not sure that would be enough.
Ideas??

Also have another somewhat unrelated question.. I was planning to heat 3 separate racks like these on the same thermostat. I would obviously test the temps before putting anything in them but wanted to get people's opinions on whether or not this would be a good idea or if anyone had any experience with this sort of thing? The thermostat I'm using is a vivarium electronics 200

Thanks,
Beth

pics of racks in question:

Shoe box racks with bottom heat tend to not have much of a heat gradient inside each tub. If over the heat tape it is 80 and the cooler end is 76-78 then it probably won't be much of an issue with corn snakes. The upper shoe boxes that are getting up to 90 will probably still have very little difference in their heat gradients so 90 on the hot end and 85 +/- on the cool end will be to hot (again for corn snakes). You can put more holes in the upper shoe boxes to allow heat to escape. You could divide the heat tape between the upper and lower sections in order to turn down the upper section. With that many shelves heat will always build up in the top shoe boxes.
Depending on the rooms temp fluctuations that the racks are in you could put that and the other 3 racks on rheostats and use the thermostat as a fail safe. Plug all the racks into the thermostat with the probe reading the rooms temp and set it to turn all the racks off when the room hits a certain temperature. All your racks would have to be identical to use 1 thermostat and even then if it fails then it fails for all.

I stopped using bottom heat decades ago and only use back heat in all my DIY racks. I also build them to use tubs with lids on especially for hatchlings.

Yeah these racks were built for geckos that didn't need heat. If I had built them for snakes I would have done things differently. But since it's what I have I want to use them.
I've decided against using the same thermostat for all so I'll be buying more thermostats I guess.
I've just got to figure out a way to get temps acceptable in this tall rack.
I could try going to back heat but I'm not really sure how I would attach it
Would rather not split it and use separate thermostats for each half, those things aren't cheap
Hmm

Yeah, great gecko racks! Still will work for snakes of course. Back heat would still have the heat build up in the upper boxes too. I'm actually surprised that there is a 10 degree difference.
Is this after the tape had time for the entire length to heat up.
Plugs at the top or bottom?
I would have all the boxes in the rack also before checking temps.
Are you keeping a variety of species of snakes or just corns?

The plug is at the top and I've had it on for a couple days now. It really depends on the time of day what the temps are.. the room fluctuates from around 72 in the early morning/night to around 80 during the day.
Checked it just a little bit ago and it was 86 at the top 80 at the bottom. However I also checked the cool end of the very top tub and it was reading 76.
I havnt bought all the tubs yet for it but if that'll make a difference I could do that and check again. I also have not put any holes in the tubs yet.
It will most likely just be corns, definitely just colubrids

I'm with daddio on splitting out the rack into 1 strip of tape for the top half and 1 strip for the bottom half. Dating back to my first rack, built in 1997, I've always done a shelf configuration to also factor in the lid; love that added layer of security. Though my first rack is no longer in use, my other racks are and by spacing them out for tubs with lids it, so far, has allowed me to luck out with the redesigns of shoe/sweater/blanket/underbed boxes that sterilite has done recently.

But back to heating. Instead of doing multiple thermostats (multiple = more than 2), I'd suggest investing into either the VE-300x2 or the Spyder Robotics HerpStat 2. Both control up to 900w, but the best part is that they both can use 2 separate probes. I'm doing this for a 4 bank of racks I have, it's 2 - 4ft W x 3ft H racks stacked and 2 - 3ft w x 3ft H racks stacked. These are 5 shelves per rack, each shelf on the 4fters can hold 4 sterilite sweater boxes or 6 shoe boxes, the 3 fters hold 3 sweater boxes per shelf and I think 4 shoe boxes (haven't used shoe boxes on the 3fters yet). These racks hold what's left of my leopard gecko collection (the upper racks), and the lower racks hold most of my snakes. This allows me to keep the leopards at 92°F, while all my snakes are set to 85°F.

Position the temp probes at the top of the rack. In your case, if you split it in half, 1 probe at the very top, and the other at the top of where the bottom split occurs. That should balance out your temps a little better.

Oh BTW, Which tape are you using? Flexwatt or THG ? If your using THG then please read their heat tape FAQ page.

My thoughts were that the tubs will change the way the heat rises from the lower shelves and also I've found that the heat tape is a little bit hotter closer to the plug.
My tallest (7 ft, 14 41qt tubs) is split.

Yeah like I said if I had built these racks with snakes in mind I most likely would have built them with room for lids.
I'm using THG tape and yeah I've read the faqs.
That's good to know about the ve300 thermostat I didn't know it used 2 probes. I'm using the ve200 currently so I may look into the 300. That would essentially mean it's 2 thermostats in one correct? You can set each probe to a different temps?
All day yesterday tho it looks like the temps have been stable across the rack with the whole rack being in an acceptable range, so I'll watch it for a bit longer to see how it does before deciding to split the rack. Even with the top tubs getting to 90 the cool end has been 80-82. The bottom warm end has been around 82 with cool end 72. I belive that would all be an acceptable range correct?

bthomas said:

Yeah like I said if I had built these racks with snakes in mind I most likely would have built them with room for lids.
I'm using THG tape and yeah I've read the faqs.
That's good to know about the ve300 thermostat I didn't know it used 2 probes. I'm using the ve200 currently so I may look into the 300. That would essentially mean it's 2 thermostats in one correct? You can set each probe to a different temps?
All day yesterday tho it looks like the temps have been stable across the rack with the whole rack being in an acceptable range, so I'll watch it for a bit longer to see how it does before deciding to split the rack. Even with the top tubs getting to 90 the cool end has been 80-82. The bottom warm end has been around 82 with cool end 72. I belive that would all be an acceptable range correct?

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You're at an acceptable range for the bottom. The top is running a tad warm. It'll "work", but you'll need to keep an eye on possible heat stress, or at the least I'd provide a larger water bowl and maybe another hide if room permits either. I seem to recall reading somewhere, maybe even a journal article, that corn snakes are more fossorial than we think. You guys are just as hot as were are out here in DFW (maybe a tad cooler for you), but with the corns possibly under ground I'd argue that anything pushing 88 or higher might be getting a tad uncomfortable. Adults might handle it, but hatchlings and juvies may dehydrate and/or have liver/kidney issues due to elevated heat in that upper portion.

As for the VE thermostat, when I researched it a little while ago it appears only the VE-300x2 handles dual probe. But that was just brief in reading the listed functions of the unit. My HerpStat 2 has 2 probes and 2 grounded outlets hardware wise, software wise I can control each probe independently.

bthomas said:

I'm using THG tape and yeah I've read the faqs.
. Even with the top tubs getting to 90 the cool end has been 80-82. The bottom warm end has been around 82 with cool end 72. I belive that would all be an acceptable range correct?

Click to expand...

Just re-reading the FAQ's I see THG has its own website now which its info is a bit different than the Reptile Basics FAQ's. It's these statements that stuck in my mind from the RB FAQ's "
"At Reptile Basics we do not recommend belly heat under 6 quart tubs (shoebox). Even with the 3 inch element this is a recipe for disaster."
"There must always be at least a small (1/8" or more) air gap on at least one side of the element."
Again, i only build racks with back heat so I really have no opinion if this is true. It stuck in my head and wanted to bring it to your attention to keep you and your snakes safe

I don't use thermostats so I'm glad HerpsOfNM can help. I agree that the upper temps need to come down. I found that snakes that acclimate to higher overall temps do not tolerate coolers temps well later. In your racks setup now just moving a corn snake from the upper shelves to the lower shelves could bring on a URI. Just food for thought

I cut a separate piece of THG for each shelf and wire them all with their own plug. I build six high, then plug each shelf into a 6-plug distributor. This way, I only have to heat the tubs that are occupied. I prefer back heat, and I enclose the entire thing in 3/4" styrofoam and seal it with duct tape to keep the heat in. The electric bills stay low, and the snakes stay warm. I like vivarium electronics thermostats.

I am considering switching to back heat but with these racks not having a back im not sure how to attach the heat tape.. actually just made a seperate post about this before seeing these other comments