I appreciate your help. I have two UTH's. The one on the "cool" side set with a thermostat @ 80 (it ranges between 79 - 81). The one on the "warm" side set with a thermostat @ 90 (it ranges between 88 - 94). These temps are taken on the floor of the enclosure, under the substrate in the hides with temperature probes/digital thermometers. I use a temp gun to double-check, and have never had a substantially different reading between the gun and the probes. The original thermostat on the "warm" side is a Repti-500, and from my readings here it is not a popular brand. The thermostat on the "cool" side, which appears to be working a heck of a lot better, is a Zilla brand. I will go tonight and get another Zilla to replace the 2 year old Repti-500. I will not risk injuring her again.