Keep melting Zoomed UTH's on my tubs... Is my setup wrong?

I've got two locking-lid sterlite tubs, prolly a bit larger than they should be, but nevertheless, each one contains a BP, a juvenile, and another a full grown adult about 4.5" feet long.

I bought these a while back:

http://www.petco.com/product/6353/Zo...k-Heaters.aspx

for the large 50-60gal aquariums (24 watts). They fit fine on the bottom, and their each connected to their own independent Reptitherm 500r thermostat.

I use a hafl inc rubber feet to keep them up off the table they are sitting on, with cermaic tile under enath the tank.

Everything was fine for a while, except now they are failing left and right. I've replace them twice on each tank within a months time, each time i pull them off, it looks like little parts of the pad "melted" here and there.

I also noticed when the pad is on, the bottom of the sterilite tub seems to bow, of course due to heat. Both thermostats never seem to kick on and off, they just seem to stay on contstantly... average house temp is 72 farenheit, and their average temps are 81-83.

Am I doing something wrong here? Using to big of UTH's? Dont want to set anything ablaze, but this would be my 4th exchange of one of the zoomed pads within a 2 month time period.

Do you use a thermostat?

uhhh, yeah...

Did you not see the part in my post where i mentioned the thermostats they are connected to? :weirdface

Quote:

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Originally Posted by beavermatic

uhhh, yeah...

Did you not see the part in my post where i mentioned the thermostats they are connected to? :weirdface

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Apparently I missed it, sorry.

What kind of thermostat?

Umm from the best of my knowledge zoomed UTH are for glass containers only. I have some Vision cages left over and wanted to use them and had a very hard time finding UTH in a pet store that will work for plastic. I would suggest some kind of Flexwatt hooked to a thermostat will be ideal for you. Or you can put stick the heat pads you are using to the back SIDE wall of the plastic, that will not burn your container as bad as the bottom.

Quote:

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Originally Posted by omnibus2

What kind of thermostat?

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Someone needs some sleep. :D From his original post.... "Reptitherm 500r thermostat"

I know very little about flexwatt, tell me what I need and I'll purchase away

if you go to reptilebasics.com they will wire it for you so all you need to do is plug it into your thermostat

all you do is tell them how much and it arrives in working order! :)

Read the ZooMed packaging - only the very smallest of their under tank heaters are rated for plastic enclosures (I think it's" 4 X 6")

Personally I wouldn't use flexwatt in your situation unless you had it permanently attached to a rack. If you just place it loose under your tub it may eventually get damaged.

This is a much better option, not cheap, but you get what you pay for:

http://www.pro-products.com/index.ph...d=55&Itemid=59


Good luck!

Have you considered the possibility that its the thermostat that is failing and not the heat pads??

On two seperate themostats?

I have three reptitemp 500r's... one is controlling just the heat panel in the melamine box for my Afrock

The other one is controlling (1) 24 watt zoomed UTH on the bottom of a sterilite tub, and (1) 15 watt UTH stuck to the back of the tub.

The other tub is using an entirely sepereate 500r, with the exact same setup.

In both tubs, the Zoomed UTH has failed twice, each one independent of the other on seperate 500r's. The other UTH on the back of both of them, have not failed.

It could be they just warp too much and flex out on the sterilite, and causes the fine wire inside the pad to snap and melt.

I did not attach my UTH to the tub. It is just set on the shelf with tub sitting on top. You may want to try that.

Zoomed UTH get too hot. They don't have their own thermostat to keep them running the same temp. As your room temps go up your UTH temp goes up. I suggest getting a thermostat or at the least a dimmer.

Hi,

Ok so going by probability alone the chances of all those heatmats and two independant thermostats going wrong seems like a long shot. Only the two reptitemps failing is less of a long shot but still fairly low odds.

But even running on full the pads shouldn't burn out and actually melt. Something somewhere is seriously wrong with the setup I think. :confused:

Can you run us through exactly how you are attatching the UTH's to the tubs again - if the feet are keeping everything raised off the desk why are you using the ceramic tile?

Where are you putting the probe for the thermostat?

And, slightly more importantly, how can the UTH's be hot enough to start melting the plastic and the animals still be alive? Theres a real risk that the heat could kill them. :(


dr del

Hi,

Quote:

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Originally Posted by beavermatic

On two seperate themostats?

I have three reptitemp 500r's... one is controlling just the heat panel in the melamine box for my Afrock

The other one is controlling (1) 24 watt zoomed UTH on the bottom of a sterilite tub, and (1) 15 watt UTH stuck to the back of the tub.

The other tub is using an entirely sepereate 500r, with the exact same setup.

In both tubs, the Zoomed UTH has failed twice, each one independent of the other on seperate 500r's. The other UTH on the back of both of them, have not failed.

It could be they just warp too much and flex out on the sterilite, and causes the fine wire inside the pad to snap and melt.

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That's the first clue. :)

You are not supposed to mix different wattage heaters on the same thermostat without having some independant controller like a dimmer switch in line with the higher rated one. Do you really need the 15W ones on the back of the tubs? I'd be tempted to take them out of the loop completely.

Now where you place the thermostats probes should hopefully give us the second peice of the puzzle.


dr del

K, 15watts gone of each thermostat, just the 24watt now.

Now heres the odd thing... If i allow the probe to just float in the tub mid air tanglinge from the edge with the top locked on, it stays around 80 to 82 degrees.... if I place it on the bottom of the tub, it literally spikes upto 86 to 89 degrees

But even then, thats not that hot, is it?

Hi,

What we recommend is to have the thermostat probe taped directly to the surface of the UTH between it and the tub - that is why you are seeing it run full on all the time I suspect. :(

You generally have to have the thermostat set a few degrees higher than the desired temp to get it spot on inside the warm end hide.

The general method is to put the thermometer probe right on the surface of the bottom of the tub underneath the substrate and adjust the thermostat until you get a thermometer reading of 93-95f.

Then you adjust the type/ thickness of the substrate until the temp on the surface of the substrate inside the warm end hide reads 90-93f.

You then check to see what the temps are on the surface of the sybstrate inside the cool end hide. If they aren't in the 80-82f range then you need to think about a little extra tweaking and possibly adding a second UTH connected through a dimmer or raising the ambient room temps.

What kind/ depth of substrate are you using at the moment?


dr del

THINK I FOUND THE CULPRIT... injection molding is the answer :)

on the bottom of each tub is a round 1cm protruding bump where the tubs were obviously connected at the bottoms during manufacturing while the plastic was being poured into the mold units. Now only does that rim make a slight indentation into the UTH, the center of the ring on each end of the tubs has a little plastic nub, just leftover from cast or injection mold of the tub manufacturing.

Whereever it leaves these indentations, it appears theres slight melted UTH, not very big, but you can tell the wires there burnt out and melted them.

Filing this down and smoothing it out would likely help the issue, but it still seems to cause the bottom of the tank to bow and warp while its on... the plastic really softens up.

If you were to stick you hand under the tub, which is sitting on 1/2' feet, the bottom part towards the center of the UTH sags down and touches the cermaic tiles i have placed underneath it. It's also extremely hot to the touch.


Im wondering if its cooking itself at the sametime from being wedge between the plastic and the ceramic.

If I raise the tub up more, the UTH just causes the plastic to sag more... It's not melting the tub, but it sure warps it.

Now with the 15w gone, should i remove the 24w from the bottom, and just let them rest on the ceramic, since it should it up anyway? That cermaic is hot to the touch, almost burning hot.... but if you touch the bottom of the inside of the tub, is warm, but nowhere near as hot as the outside.

Hi,

What kind of tubs are these you are using?

I'm thinking you are going to have to replace them if they are bowed that much - but once the UTH isn't running full bore it might not be as big a problem.

It does sound as though all the movement and point stress is causing localised damage to the UTH's which is making them short out or seriously overheat in spots. Good detective work. :gj:


dr del

Dr del,

So the UTH should only take up one half of the entire bottom of the tub?

Because literally, this 24w large takes up almost the entire base of the tub where the snake crawls.

directly touching the plastic where the UTH is on the floor of the tub, my thermometer sensors states its 92 degrees (ouch)

I'm using just paper towels, ovelapping each other, so its slighty warm on the top.

edit: I will post some pics of the current tubs here in a couple of hours, busy doing work at home right now

maybe yourll be able to see for yourself, ill take pics of all angles and what not

Hi,

Your hot end should be about a third of the size of the tank if at all possible - that leaves it pleanty of room to move away from the heat and thermoregulate properly.

You might be able to set both tubs so that both tubs are on the same mat at the warm end connected to one reptitemp set to give you the 93f and the same placement on the cool end with the other reptitemp set to 82f.

I'm not sure how you have a UTH that is hot enough to melt and deform plastic and feel extremely hot to your hand and still only be getting 92f inside the tub on the surface of the plastic - how thick are these danged things?

Leave the censor there for a little while and see if it goes up - this is where the infra-red thermometers win. They are also great for chasing the cat with. :twisted:


dr del

I actually find the ZooMed UTHs are a bit hot--I don't have a thermostat, mind you, but my IR thermometer says my 20gal ZooMed UTH is currently 119F. I've been keeping it side-mounted on a glass tank, rather than under, because I worry about it damaging the desk and/or the ball pythons.

I've got a Desert Heatwave UTH under my big glass tank. I think it's ExoTerra? Not sure. It stays a lot cooler without a thermostat, maybe 85F. Even so, the girls in that tank tend to hang out on the edges of the hot spot, rather than right on top of it.

I've also heard that these thing tend to run hotter over time. I don't think I'd keep them as a long-term heating solution for racks, because they kind of worry me.

Hope the flexwatt works out for you!