Quote Originally Posted by proballo View Post
2 digital one on each side and a temp gun to check the surface temps. Hot side 85-90 cool stays 75-80
You should need a light and a UTH on the same side. The UTH will provide the hot spot, and the lamp should increase the ambient air temperature to around 80*. Just try one lamp on the cool side and just the UTH.

Stick one of your probed thermometers right on the glass where the UTH is.