hey Mike, the concern i have about heat tape is the variability of it...
if you just "run it", it tends to "pulse" quite a bit, where the heat fluctuates a lot. and i have certainly seen a number of cages get burnt or melted from uncontrolled heat tape, so i would most likely put a controller on it.
plain $6 rheostats aren't a good choice for heat tape (flex watt). they heat up HOT, and don't have a way to dissipate the heat. look for a higher caliber rheostat that has a heat sink built in to dissipate the heat build up. the ones we used (for a couple of years straight) were the size of a light switch, box and all, and had some nice metal fins. $20 or so...
we have since set up our heat tape sections (for rubbermaid snake racks, 20 feet long) on Ranco thermos like the Boaphile sells, and i like those a lot, from a safety and effectiveness point of view.
on a final note, from a large thermal mass point of view, we run a couple strips of 4 inch heat tape, about a foot long each, at the dirt line on our monitor troughs, and that is run full blast, but there is enough mass (1000 pounds or more of soil) there to dissipate the heat well there, so full blast is not a problem for that application.
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robyn@proexotics.com
Pro Exotics Reptiles