Why THE HECK is this so hard?!?!?!?!?

[Little Miss]

I am so frustrated right now! I am desperately trying to regulate my cage temperature. Let me take you on my adventure:

I have two 10gal tanks, each with a 10-20 gal Repti Therm Heat Pad and a digital probe thermometer attached to the bottom cage on the hot side. I used a lamp dimmer on the Med setting to regulate the heat(the low was too cold and the high was too hot.) But the best temp I could get was between 93-94*F. I don't want to burn my snakes, so I bought a $25 Zoo Med Rehostat. I put it on the medium setting, and a few hours later went to check on the cages. It was 114*F!! I freaked out- yet my snakes seemed to be loving it they were curled on hot side. I turned it down to low, and gave it another few hours. The temp then read around 105*F. Frustrated, I unplugged it and put the dimmer back on. I then rushed out and spent $55 freakin' dollars on a Zilla Thermostat. I placed the probe on the bottom of my tank on the hot side, plugged it in, and set it to 85*F. I watched the temperature in my cage CLIMB to 109*F before I quickly unplugged it!!!!!!!! I don't know how hot it might have gotten! I now have the the Thermostat turned down to 75*F, and in the last 30 mins my cage temp is where it should be. We'll see where it goes...

But why THE HECK is this so FREAKING hard!?!?!??!?!

*Thanks for your help *

 

[bitsy]

I can only speak for thermostats, but I never trust the numbers they display. They behave slightly differently depending on what size/wattage/make of heat mat you use with them.

Trial and error is the best way of setting them up, as you've found. If the thermostat says 75 but the temp on the floor inside the tank immediately above the mat reads 85-88, then that's fine.

My only other thought is - have you tried taking the temp with a different thermometer, just in case it's this that's out?

 

[bkelm18]

Using a rheostat/dimmer is tricky. There's a sweet spot, trust me. You can achieve temps in the mid 80's, but move that thing a millimeter in either direction and the temps shoot up or down. It's tough to get a hang of.

 

[Nanci]

If you spend just over $100 on a Herpstat, it'll be the best money you ever spend. You just set the digital thermostat to 85F and it keeps the UTH at that temp. No messing around with adjusting it. They are on sale till Friday. http://spyderrobotics.com/ Yes, I have those on every single viv I have except one. Even on lone 10 gallons. It's so easy.

 

[caz223]

This is how I do it.

Put your snake somewhere else while setting up your t-stat.
Tape the thermostat probe directly to the bottom of the heat mat with duct tape or packing tape. Just affix it so it isn't coming off, and has good contact. I use reflectix (Radiant insulation.) and spray glue for permanent installations. It looks somewhere between bubble wrap and foil tape.
Now tape your digital probe to the glass directly in the center of the heat mat, inside the tank.
Now plug it in, and let it run.
Set your thermostat at 88-90F. (I use redundant thermostats, I set 1 at 88F, and 1 at 90F.
Make sure you have the tank set up on hockey pucks or something so that the heat doesn't build up under the tank, that will throw off your thermostat reading. (Unless you use reflectix and spray glue.)
After at least 12 hours, check on it.
The top probe should be a few degrees colder than the thermostat.
Then I check those 2 with a temp gun (I use a 412L from reptile basics.)
I usually run at 88F-90F on the thermostat (I use double Rancos.) Then again, I use aspen, and have at least an inch of aspen in the tank.
If you go over (Roughly.) 90F, the heat tape will do something called thermal runaway.
As it gets warmer the resistance changes, as the resistance changes, more current flows through it, as more current flows through it, it gets warmer.
This is common in semiconductor devices, heating elements, inductors, and other electronic components.
After you have it dialed in, and the temp stays consistent, remove the tape and any adhesive inside the tank, and put your substrate in there, and put the probe just under the substrate.
If you use thin substrate like paper towels or newspaper, put it right on the glass.
I check for agreement between my temp probe and my temp gun, and make any adjustments necessary.
Just don't go over the rated temp of your tape, or it may develop hot spots.
(Localized thermal runaway.) Your temp probe may not be under the hot spot. Most tape is rated around 90-95F.

 

[alan]

As it gets warmer the resistance changes, as the resistance changes, more current flows through it, as more current flows through it, it gets warmer.
This is common in semiconductor devices, heating elements, inductors, and other electronic components.

Semiconductors work this way, but not heating elements. The heating element itself will work just the opposite.

 

[Little Miss]

OMG! It was stabilized at around 86*F a few hours ago, and now I see it's 109*F in my cage and my Themostat is still heating!!!!!!!!!!!!! (Mind you it's set on 75*F. )

I thought the thermostat was a "set it and forget it" - I mean it's a THERMOSTAT. I appreciate your suggestions thus far, and thank you, but i'm irritated because I feel like I shouldn't have to spend $100 per tank or a go through a bunch of hassle to get a stable temperature. Obviously that's not your fault; I'm not directing my frustration at you. I had a stable temp with the dimmer, but it was a bit too warm.

For now, I'm just putting it back on the lamp dimmer. At least it didn't go over 100*F. Is air circulation under the tank that important? The heat pads come with little stickies that raise the cage up. In the past I raised the cages several inches, but the cage temp remained the same. UGH!! I have now spent two sleepness nights on this.

A friend of mine who has snakes said she glues reptile carpet to the bottom of her tank so the snakes can't burned, but some people on this site advised against that. I do have aspen bedding on top it to absorb any possible moisture. I already glued carpet down to one of my tanks, and I do feel safer that way knowing I won't have BBQ snake.

 

[Nanci]

Okay. Is the probe fixed to the middle of the UTH, directly on the glass, not floating around? I would imagine a snake could get under glued carpet, I wouldn't trust that. A couple temporary fixes would be to first get the probe fixed in one place. Aquarium silicone makes a good glue. If you use any type of tape whatsoever, the snake _will_ get into it and may get injured. That being said, I have used aluminum tape to secure wires in a viv because it is very unsticky after it comes loose the first time.

Realize it is quite likely it will take you hours or even a couple days to get the thermostat dialed in to the temp you want. Check the temp every couple hours, and make a very minor adjustment. You need a probed thermometer, preferably with a high/low memory so you know what is going on with the UTH all the time. A temp gun (they are very inexpensive now) will also help because you can check the UTH all over its entire surface, not just the one spot where your probe is. The stat probe and thermometer probes need to be right next to each other. If you still can't get the temp down low enough, you can either go to the next size smaller UTH (makes a HUGE difference) or put a piece of ceramic/clay floor tile right over the UTH. The snake can't get under or move the tile, and it will suck up some of the heat. It may also help to create a small air space under the viv, say 1/4 to 1/2 an inch.

So, there are two kinds of thermostats. Anything under $100 or so is going to be an on/off thermostat. You set the temp. It turns on and heats the UTH till it reaches the set temp, and then turns off. Unfortunately, the UTHs temp will continue to rise a few degrees. This isn't so critical (unless it just bugs you, like it does me!) and if you allow for the actual high temp the UTH reaches being slightly higher than what you set, maybe 5F than what you want, it's okay. So then the UTH cools down, and at some point, maybe a degree or two lower than your set temp, the stat turns back on.

Then there is the proportional thermostat. There are several manufacturers and the stats are going to start at about $100 and go way up from there, depending on what features they have and how many separate settings you can make. How they work is you set the temp digitally. The accuracy is =/- 0.1F. The thermostat supplies power to the UTH. As the temp nears the set temp, the stat drops the amount of power supplied so the heating slows down. 30%, 20%, 10%, off. This way the UTH does not exceed the set temp by more than _maybe_ a degree at the most. Then the moment the UTH falls even one tenth of a degree below your set temp, the stat begins supplying 10% power to bring the temp back up instantly.

The degree of complexity of the device dictates the price. You get what you pay for.

 

[caz223]

Semiconductors work this way, but not heating elements. The heating element itself will work just the opposite.

Not to split hairs, but isn't heat tape a heating element?

I'm not writing a paper, just including some basic examples.

 

[caz223]

No need to raise the tank a long ways, just as long as there's _some_airflow under the tank.

 

[anankae]

Wow, you all like to keep your corns warm. I don't go to that much trouble for my ball python, and she's the one I want to keep warm. (I try to keep my boa warm but for some reason, she likes to coil near the top of her tank {on branches} and stay cooler).

What I like about corns is they're not as fussy about temps. They can go a little cooler than the other snakes and be comfortable. If I can keep ambient temps 75 to 85ish, they're fine. Don't even worry about basking spots.

I got one of those repti therm mats at the pet store cause I couldn't find what I wanted, a t-rex. Did what the instructions said not to do and stuck it on the bottom and it got too warm, so I did what the instructions said to do and stuck it on the side (it's on my BP's tank). Ordered another t-rex off the web. I like them better cause they don't get too hot and you can slide them under the tank.

When I put my BP and boa in bigger tanks, I probably will go to the trouble of setting temps with probes and thermostats but with the corns? They're happy if they have a hide (or as one of mine does, newspaper to burrow under), fresh water, food periodically and ambient temps around 80F. As it's been colder they've been less active, but that's what they do when it gets colder, yes? (got a space heater running in their room so the ambie

 

[anankae]

whee, where's the edit button? so the ambient temps stay right at 80F.

 

[caz223]

What you're describing is usually attributed to the cheaper thermostats.
I recommend Ranco thermostats as the cheapest thermostat that I consider reliable.
Anything cheaper and you really would be safer with a dimmer switch-if you monitor the temps daily.
I use four (4) Ranco thermostats to control each rack.
I have two (2) independant sets of heaters, each controlled by a dual Ranco setup.
If 1 Ranco fails hot, the second Ranco takes over and regulates at a slightly higher setpoint.
If a Ranco fails cold, they have the second heating system.
It sounds expensive, but is much cheaper than a rack full of cooked snakes.

 

[anankae]

Just want to add it doesn't take rocket science to figure this stuff out. After reading this thread, I went out and got a little indoor/outdoor thermometer with a sensor. Dropped it down the cool side of the BP's cage and it read 81, stupid Petco gauge was reading between 1-2 degrees of that.

Dropped it directly under the heat lamp on the warm side, it came up 96 which is about 4 to 5 degrees warmer than I want it (but still well under the lethal range). Gonna go to the pet store to pick up a lower wattage bulb.

Still not bad for guestimating. After I set the BP's cage, I'm gonna test the others, but I suspect they're also within a few degrees of the range I want them to be.

 

[jlindp]

Little Miss, I'm not sure why you're having difficulties. Hopefully you didn't buy a dud thermostat. I have 2 of the kind you're using, the Zilla kind, and both work perfectly fine. They keep all my mats between 83-86 degrees. I have the probes taped to the bottom of the heat mat, instead of inside. When it was inside one of the tanks, my corns would get under the substrate and multiple layers of newspaper, and even with a thermostat, I wasn't comfortable with them being just on the glass. One tank has a digital thermometer and the rest have dials, but since I've got my heat gun now, it's all I use.

Hope you can fix the problem without further frustration! :}

 

[Buzzard]

Sound like A. either bad Thermometer or B. a bad Thermostat I use a dimmer and like other have mentioned getting it just right can be tricky.....

 

[Little Miss]

I will go out and get another thermometer just to make sure, but will 95*F glass burn my snake? I love the idea of putting ceramic tile over the UTH in place of gluing carpet.

 

[bitsy]

Their ideal maximum is 90 degrees. Anything over that for a sustained time risks causing neurological damage.

For some reason, they don't have the instinct to move away from a surface that is too hot - they have been known to actually sit on things like bulbs that are so hot they cause burns. You need to get surfaces below 90 if you can.

 

[bubba6]

had the same problem then I bought the zilla and now run two tanks at perfect temps! if we are talking about the same thermostat, how do you know what its set at? (there are no numbers on the dial) the zilla rheo did the same thing...all the way down..way to hot!! should be a recall. all the same products and can't be used as directed? good luck

 

[danielle]

I believe this is not thermostat error, but user error. Where are you putting the probe from the thermostat and is it staying in place? If the probe isn't secured in the cage and UTH under the cage your thermostat can't work.

Drill a hole in your cage only big enouh to slide the probe in, then fix the UTH under the cage, but not inside; last use a dab of silicone to glue the probe down in the cage over the middle of the UTH. This is your problem