You're assuming that the animals died because they were overheated. That did happen one time, but another time I actually lost animals because the thermostat failed a day after feeding. A couple of the snakes that were digesting their meal suddenly had NO heat and the half digested food started to rot and they bloated up and died. One time they did overheat, because there was suddenly no regulation of the temperature and the heat tape was going at full speed. However, I don't know where you get this heat tape, but the only kind that was available to me and most other people at that time only came in two wattages. You could either get flex watt heat tape at 10 watts per foot or the wider stuff at 20 watts per foot there were no other choices available. (and by the way, one of the snakes that died from bloat was in a boaphile rack)