Heating Safety

[Reptilebasics]

Every year I try to put together and update some important notes for reptile keepers both new and advanced. I learned long ago there is always something to learn- even things we think we have mastered. Most discussion in this hobby tends to be about new morphs, breeding tricks, and the like. There are several good forums out there where caging and heating are discussed at length and there is now a lot more educated users out there with some really good, accurate advice. This past year there have been a few high profile fires. In several of these heat tape was not involved but the lessons are very applicable to most any heat source. I visited the Pro Exotics facility a week after their fire and it was one of the most devastating things I have ever seen. The loss of animals and time is unimaginable. The one good thing that can come from this is awareness- I have seen a huge increase in safety related questions both personally and in forums. Below are some bullet points on the topic of heating- specifically racks and heat tape.

Which size heat tape?

This can be tricky sometimes as there is not necessarily always a clean cut answer. A good place to start is you generally do not want to cover more than a third of the bottom of the tub. This will give you a good gradient in most cases but the really important thing is animal safety. You must always plan for failure- what happens if the heat tape goes to full power due to thermostat failure, probe being dislodged or some other reason?

Anyone who has been in this hobby any length of time has heard of someone “cooking” a bunch of animals. This happens due to a failure of some kind. But did animals have to die due to overheating? If your initial set up was correct, probably not. For example- I personally will not make a shoebox (5-6quart) rack for commercial sale that uses belly heat, even the 3”/ 6 watt. I learned this lesson myself early in my reptile keeping days and it is also the common thread in the overwhelming majority of “cooked snake” stories. Hatchling racks. The animal in the tub simply does not have enough room to get off the heat. The tubs ambient very quickly gets over 100 degrees and everything in the rack is dead. This happens in less than 30 minutes in most cases. There is simply no room for failure with this set up. IF you have any failure you are done before you got started.

Of course, there are many who simply will not believe you can do without belly heat on a shoebox or any rack. First, that is not true. Even Ball Pythons do very well in 6 qt. tubs with back heat in a 70 degree room and it is almost impossible to cook snakes in a back heat rack with a room temp below 78. The small tub size actually lends itself to this very application.

Larger tubs, say 12qt and up, have much more air volume and floor surface area so your margins of error is quite a bit higher. The bigger the tub the safer this gets and depending on the species being kept these larger tubs often benefit from belly heat. Same rules still apply. I do not like the idea of using 11” heat tape for belly heat in a 41 qt tub in most cases. Even though it is at or under 1/3 the tub the potential for overheating is very great!
Try your racks out! Without animals in them plug them in full power for several minutes and see what happens. Monitor this carefully and don’t walk away from it! See what the max temperatures are. Know your system! Your heat tape will be fine operating like this for a short period of time, say under 45 minutes. By then you should have the answer you need. If the coolest spot in the tub is 100+ you are setting yourself up for trouble.

Why does heat tape fail?

Almost all heat tape failures come from overheating. Sometimes the excess heat is not obvious though. I have both seen and had described to me roughly 6 or 8 times per winter season. Some interesting trends- Very seldom does this happen in the summer months and it always occurs under tub(s) in rack systems. To date I have not seen a back heat set up fail.

This tells us quite a bit. The first thing to realize is heat tape is a tool to create a basking temperature for your animals, not to necessarily heat the enclosure. There is a big difference. A good example is the 41 quart tub with a Ball Python. In the summer months the typical room temp seems to be mid 70’s. With the heat tape running at about 92 you will see about 88 inside the tub on the floor. This will give you about an 80-82 degree ambient with 4” heat tape. Now, if the temps in the room drop your thermostat will naturally up the heat tape power to make up the difference but this is not really linear. A 2 degree drop in room temp does not necessarily mean a 2 degree rise in heat tape temp to maintain your floor temp in the cage. It may be closer to 4 degrees. You will also see your ambient tub temps take a nosedive below 70 degrees room temp. If you attempt to offset a cool room with heat tape power output you will be setting yourself up for trouble. Think of it like trying to heat a house with your oven. You can do it but not for long. Bottom line, room temp is critical. A couple of degrees can make a huge difference in your ambient tub temp and the longevity/safety of your heat sources.

Substrate is another common issue. Aspen, cypress, and other similar substrates act as a great insulator. Let’s say I have my stat probe on the heat tape (belly heat rack) and my tape is running at 92. What is the heat tape temp under the tubs though? If I am using paper or a thin layer of aspen then probably 1 or 2 degrees more than that. Still OK. Now use a 2 inch layer of aspen. There is now almost no heat dissipation and a lot of heat will build up between the tub bottom and the tape. Potentially 115+. That is not a hazard in itself, I am 98 degrees, but it will wreck your heat tape. Failure will occur. The substrate is a blanket that will be a big problem, especially in the winter when the room temp drops. Keep the substrate thin and let that heat dissipate! Your animal will find the heat under the substrate, don’t worry about the temp of the substrate on its surface, what is it on the floor of the tub?
Heat dissipation is why you don’t see back heat fail, the heat always has an “out”. I have tested 11” heat tape at full power for months without failure like this. Put the same heat tape under a tub with 2” of aspen and I can get it to fail in days or less.

Summary:

Know your setup and its capabilities. This applies to cages with heat panels or lights, racks, 10 gallon tanks, etc. What is the highest potential temp of my setup? Will it kill my animals should there be a failure? What is the actual temp of my heat tape? Temp of heat tape under the tub(s)? Can my probe become dislodged easily?

I would suggest a monthly inspection of your setup. I know, a pain in the rear but think of the risk of not doing it. It is actually pretty hard to start a fire, especially when dealing with PVC or metal racks and cages but what about all of the money and time you have invested in your animals you can lose even without a fire? What about the lives of the animals themselves? The most distressing thing about my visit to my friends at Pro Exotics after their 2011 fire was the loss of the really amazing animals they had. Sure, the dollar amount was very high, the building itself was a total loss, the equipment, etc as well. On and on. But the incomprehensible amount of effort was what hit me. I keep very few animals these days, usually under 50, but I know how much time and effort is in that. Multiply by 1000. I can’t. How do you replace 20 years? How do you replace 5? Could the fire have been prevented? We do not know yet as of this writing, the investigation will continue well into 2012, but the question is still there. This fire has led me to test several heat elements we use in this hobby in new ways to learn how they work and more importantly do not. This has already led to some new ideas to incorporate in future products to help prevent these events. There is always something to learn.

You do not know if or when something like this will happen but one thing is certain, if you are not diligent with anything that is plugged into the wall you are that much more likely to find out.

[Vypyrz]

Great post Rich. Thanks for the info...

[Mike41793]

Very informative. Thank you

[Fila]

I was thinking about the 3 " under the tub in a recess and the next size up as back heat for the bottom three levels in a 7 rack tall system of 28 or larger quart tubs. The top four will have belly heat only. I also have mini fans on each level as my racks will be well insulated except for the front. Heater will be set on 70. I plan on using separate thermostats for the top and bottom of the system. These racks are being built as part of the wall in a bathroom we have gutted. The material will be pvc for the shelves.
*Fila*