yea, 85 is high, it stays like that for a couple second then it automatically drops. for temp measuring i always have a zilla thermometer that does temp and humidity, then 3x times a day i use my temp gun, the stat is a light dimmer i bought from lowes, its a sticky on the bp forum, and was recommened to me by a breeder
The dimmer method works, but works best if your ambient temps in the room are rock steady. Problem with them is that they supply a steady amount of power, so if the ambient temp changes then so do your cage temps.