I have about a 5 degree change in the room (65-70). I just set the dimmer when the room was at 70 and i set the UTH to 86.5 degrees so that was as hot as it is going to get. The mat changes from about 83-87 and i've never adjusted it since then. Eventually i'll switch to a T-stat but for now, this works great and i might as well get my money out of it! It's the best rheostat that i've used and it was worth every penny. Maybe for Christmas i'll switch him over to a T-stat but if you want to save some money and only have about a +or- 5 degree change then a Rheostat is fine and i would recommend the Leviton Dimmer that was mentioned earlier, then it'll give you time to save up for a nice T-stat, I was thinking about getting the one that Fatman mentioned and i could give a review on it... It looks good and has a digital display and it's cheap! so i don't see anything wrong with it