Yikes. Its not like the UTH goes up to 150 degrees to get the tank to 90... so unless its sitting on styrofoam or like I don't know, kindling maybe, you shouldnt be scorching the furniture. As long as your hotspot, which should be in the hide, is staying up and your tank gets up past 78 during the day 71 isn't that big of a deal over night your snake will just stay in the hide.

Maybe look at the wire of your UTH see if there is a fray?