Heating tubs?

Trollbie · 05-20-12, 07:26 PM

At first I had a small ZooMed UTH under eat connected to a rheostat. Everything was great and stable for 4 days and then it got too hot for some reason even though I didn't change the settings on the rheostat. The other UTH that's connected to the same rheostat is fine.

I got a bigger UTH since that one was too small anyway, and glued bottlecaps on the bottom of the tub to increase the airflow underneath. Left the rheostat on low. Everything was fine for a night and then within a couple hours the next it got hot enough to melt the plastic a little. I was checking the temps with a temp gun every couple hours and it was stable. So I'm not sure what happened.

Then someone recommended a human heating pad. So I bought a new tub and a Sunbeam heating pad. Everything was perfect until I realized that it has a auto turn off after 2 hours and has to be manually turned back on.

I looked but they don't sell them without the auto shut off anymore. I could try opening it up and disabling the timer on the circuit, but I'd rather take an easier route if there is one because if I screw it up then I can't return it.

What could I do with the UTH to not attach it to the tub, but still have it heat the tub enough? I'd get a thermostat, but at this point I don't trust the UTH on the plastic anymore because the second time the heating pad wasn't even that hot. I could touch the tub and it was warm, not hot, and it still melted a little.

The tub I'm using is a Sterlite tub

youngster · 05-20-12, 07:37 PM

Rheostat= bad. That's your problem, get a real thermostat and this won't happen. And just stick with a ZooMed UTH/flexwatt.

As long as you have a thermostat you will be fine, plenty of people use UTHs on plastic, just don't set it above 90.

Trollbie · 05-20-12, 07:41 PM

Quote:

Originally Posted by youngster

Rheostat= bad. That's your problem, get a real thermostat and this won't happen. And just stick with a ZooMed UTH/flexwatt.

As long as you have a thermostat you will be fine, plenty of people use UTHs on plastic, just don't set it above 90.

But it only got hot enough in the middle of the pad. And even then it wasn't THAT hot... I'd rather not put the UTH directly on the tub anymore, but I don't really know if cardboard or foil or something in between the UTH and the tub would help.

youngster · 05-20-12, 07:46 PM

Well get a thermostat and raise it on bottlecaps like you did. Problem solved.

If you place the probe properly I don't see how it could get hot enough to melt the plastic even a little.

Trollbie · 05-20-12, 07:53 PM

Quote:

Originally Posted by youngster

Well get a thermostat and raise it on bottlecaps like you did. Problem solved.

If you place the probe properly I don't see how it could get hot enough to melt the plastic even a little.

I still won't trust it. It was okay this time because I was home to keep checking on it, but that won't be the case during the week. I don't want to risk it.

youngster · 05-20-12, 08:44 PM

Hmm, I'm not sure what you're hoping to hear then.

Can you make a new enclosure?

Trollbie · 05-20-12, 09:17 PM

Quote:

Originally Posted by youngster

Hmm, I'm not sure what you're hoping to hear then.

Can you make a new enclosure?

Not till august

**millertime89** · 05-20-12, 10:49 PM

Already sent these pictures to Trollbie, but I'll post them here to show others my solution. I knew I wanted as little of a gap as possible, but I couldn't find something that I really liked that would work so I spent a half hour or so wandering around Home Depot and eventually came up with this.
Here you can see there's less than a half inch of space between the UTH/flexwatt, but still a gap so its not actually touching the plastic, just the wood.

Here's what I use as spacers, copper plated adjustable brackets, they were less than $.50 USD IIRC.

the extend too which is nice. I don't think I've seen any tubs much wider than 20 inches.

I do take a hammer and flatten the ends so they lay flat. But if you do have a tub that's wider than 20 inches, it splits apart and you can use it as two pieces with a gap in between.

Trollbie · 05-20-12, 10:54 PM

Thanks KyKy!!! That's exactly what I was looking for!

**millertime89** · 05-20-12, 11:15 PM

No problem ZuZu, I tried finding them on Home Depot's site but couldn't, might just have to go and wander the aisles. I do that looking for tools sometimes anyways.

Trollbie · 05-21-12, 11:08 AM

What temp do you have the t-stat set to?

**millertime89** · 05-21-12, 11:49 AM

between 86 and 90 depending on species. I get hotspots ranging from 82-88 on top of the substrate. Most of em will push the substrate out of the way if they want the direct temps. The 88 hot spot was measured during the day when the heating element didn't have to work as hard to get to 90 so more heat made it through, if that makes sense.

Trollbie · 05-21-12, 11:53 AM

Quote:

Originally Posted by millertime89

between 86 and 90 depending on species. I get hotspots ranging from 82-88 on top of the substrate. Most of em will push the substrate out of the way if they want the direct temps. The 88 hot spot was measured during the day when the heating element didn't have to work as hard to get to 90 so more heat made it through, if that makes sense.

Yeah thanks. I just wanted to see how much heat is lost through the gap

**millertime89** · 05-21-12, 12:04 PM

minimal, I think the plastic actually absorbs more. The gap is minimal. It looks like the probe touches both the tub and the heat mat, so its very small.

Trollbie · 05-21-12, 12:16 PM

Quote:

Originally Posted by millertime89

minimal, I think the plastic actually absorbs more. The gap is minimal. It looks like the probe touches both the tub and the heat mat, so its very small.

Okay awesome. How warm is your room? Mine stays pretty cold so I may have to set it higher, but I'll try what you said first and go from there.