There are a few options for you, but I am curious about a few things.
What size tank do you have?
What type of substrate do you use? Is it moist or dry?
How deep is the substrate over your UTH?
What type of lid do you have?
Do you have any trouble keeping the humidity level stable?
Is the tank positioned next to an "inside" wall in your home and away from drafts? (like an air conditioning vent, etc.
Maybe I can give you better choices based on the answers to the Q's
