Reptile & Amphibian Forums

I have used an on/off thermostat for my hatchlings and yearlings for the past several years without problems.....today was was the day I realized that was a HUGE mistake.

Sometime yesterday my on/off thermostat got stuck in the ON position and cranked my heattape temps to 140 degrees.....effectively killing 3 of my 2006 yearling holdbacks (an axanthic female and 2 het axanthic females all in the 800g range)

Thankfully all of my 2007s were alive....but talk about a REALLY bad morning.

Lesson learned.

My question is do the proportional thermostats guarantee to NOT get stuck in the "ON" position? I use helix on my adult racks and I'm wondering if I need a redundant one on them as well?

Any advice would be great as I'm in the market for a new thermostat for the hatchling/yearling rack.

Thanks in advance.
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John Dague
Midwest Reptiles
www.mwreptiles.com

I have backups for ALL my thermostats. Johnsons for my herpstats and if nothing else I use zoo med 500r for backups on my hatchling racks that use just the on/off johnsons. All the backups are set at 2 degrees above the setpoint of the main thermostat.

Wow, sorry for your loss. That's awful.

If I used flexwatt, I would probably back up all my thermostats. I don't worry about the zoomed heat cable as much. I don't think it gets as hot as flexwatt. I let the cable run on full power in an empty rack once and the temps only got to 95-98 in the hotspot. I like the herpstat better than the helix, too. At least it has an alarm so you'll know there's a problem if you're home.

Hope this helps,
Shelly

Another important consideration is how much heating you have in the cages. There's no reason to have so much of whatever heat source your using (I'm guessing it's flexwatt or heat cable). I recently had a thermostat probe come off of the flexwatt in a Boaphile rack sometime in the middle of the night. Since the probe was hanging in the air, the thermostat was basically stuck in the "on" position. The hot spot temps only got up to about 100 degrees, the air temp was lower than that. I'm sure if I left it for a while the results would be bad, but the snakes were fine at those temps when I discovered the problem in the morning.

I should have probably specified....it was 140 degrees on the tape.

It sounds like the answer is to get backups for everything. Maybe triple redundant....a rheostat to keep the max below say 100 degrees on the tape and and on/off and then a proportional.

Thanks for the condolences.....
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John Dague
Midwest Reptiles
www.mwreptiles.com

Don't use a rheostat with a herpstat or helix, it will make the thermostat work overtime and may never get to temp. Two thermostats should be enough and always use the lowest wattage you can get away with. I threw out all the 10w 3in flexwatt and use 4in 8w. Much lower temps at full on and better distribution. On my adult racks I have 11in, but it is between tiles so if they do burn through the tile is fireproof. The tiles also distribute the heat well and offer gradual temp changes when I induce the night drops for breeding season.

I'm curious to see a pic of your heat tape setup as you described it being between tiles.................

"On my adult racks I have 11in, but it is between tiles so if they do burn through the tile is fireproof. The tiles also distribute the heat well"

Thanks!!

Brian

Got to get some pics I guess, I rout the MDF with 12" squares in the back, get cheap white ceramic tiles and put the flexwatt between the tiles. Ceramic tiles are naturally fire proof so if one was to short and burn through, the tiles keep it from burning the tubs but I have never had that problem as the tubs never come in contact with the flexwatt.

I use a double thermostat from Boaphile.....

it actually went crap a couple weeks ago......not sure what's up.....but it didn't stick ON it just goes to Error 2 and won't turn on.......at least they don't fry.....(room is warm enough to keep them fairly well.)

I got a new single yesterday till I send the double back to be checked and fixed/replaced....

......no way I was using a single........

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Sorry if I missed it, but what was the brand of the thermostat that failed.

BAH-1000 from big apple herp...

It's actually the 2nd one we have had that failed...different rack though. The other one stuck "OFF".
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John Dague
Midwest Reptiles
www.mwreptiles.com

There is no need to get three redundant backups if you have one good thermostat that has these features built in. I would recommend the Herpstat Pro. I used Helix's for many years and would not recommend them at all.
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www.strictlyballs.ca

is to go with a redundant system. All proportional and a lot of the non proportional thermostats have the output controlled by turning on and off a triac. This is a solid state component with no moving parts so the chance of failure is very low but with any electronic component the chance is there. If this component does fail it can fail in the on state. This is not something that can be controlled by the thermostat manufacture other than using the highest quality and overrated components to lessen the possibilities. Some on/off thermostat like the Rancos and Johnson Controls use a relay to turn on and off the voltage. The relay is a mechanical switch that can also fail under rare circumstances. Your best bet is to use a good proportional thermostat as your main and a relay based as a backup…

Here is a post from Dion at Spyderrobotics I found on the Bob Clark forum that discusses basically the same thing just better….

“One thing to watch out for in the small cheap thermostats is heat. We all know heat is the killer of electronics and the majority of the under $50 thermostats (the one in question, 500r units, ect) use what is called a Triac. All the wattage runs through this component and is the same component used in proportional thermostats. The difference is often the cheaper products use a component that is to spec but do not necessarily count for all the extra heat. Those have small packages with little room for circulation. When a Triac fails it has a high chance of failing in the on position. So keep an eye on the heat of the case and make sure the thermostat is mounted where it can get airflow. The cooler, the longer it will last. We take the other approach and assume the spec is not enough and overbuild everything to prevent this. Where a 5amp triac could be used we put in 15's. They take more heat and handle voltage spikes where others would fail. Its like having a Hemi in grocery wagon. You don't need it buts its nice to have just in case. Since the heart of the circuit is overbuilt we have the fuses there which should trip before something like this happens giving the much preferred "power off" failure. That being said I believe the ultimate setup is to have a relay based thermostat directly into the wall(think ranco or johnson controls, maybe us one day) and then a proportional thermostat plugged into it. This way should you ever have a lightning hit, voltage spike, or just a faulty component in the proportional (or any triac based thermostat) the old fashoned relay thermostat will take over and save the day.

Dion Brewington
Owner, Spyder Robotics”

Great post.

I took this advice to heart and ordered backups.

For now I'm going to run a pair of the new BAH-1000 models (with a new protection circut) on the hatchling rack, redundant style.

I also ordered a 3rd that I will use as a backup for my adult rack which has a helix as it's main controller (courtesy of an ASR rack)

I will also be ordering a backup for my incubator in the spring. (currently uses a herpstat)

After I move into my new house with more snake room I will upgrade everything. I'll do a herpstat II or herpstat Pro for the main source and then backup for each seperate source in the form of the boaphile ranco thermostats.

Sleeping soundly from here on out seems to be worth these upgrades.

Thanks for all the responses!
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John Dague
Midwest Reptiles
www.mwreptiles.com