Make sure you use a thermostat and the thermostat probe is taped under the UTH. Also you have to tape a temp probe on top of your substrate for accurate temps of the substrate. You most likely have to go higher on the Thermostat to get the desired temp on the substrate. I am using tile and my thermostat is set for 100 and the substrate is at 91.5. If you put the thermostats probe on the tile and it comes lose the mat won’t turn off and your leos can burn. By doing it this way at most my stats will hit 100. just make sure you use good tape to hold the probes in place. I used silver metal tape that is used for AC ducts.