I know that UTHs are one of the preferred methods of heating snake enclosures. However, this is the second time I've used one and the second time it didn't get the temps anywhere near high enough.

I had a 5 watt pad for my python that came with his 20 long tank. It only heated the ground up to about 72-ish. Now I have another pad for my boa, and again, it's only heating up to about 72 - 75 degrees. I added a heat lamp to both tanks to raise the temperatures. Directly under the light (about 3 or 4 in) gets to about 102, and after another few inches it gets around 85. Under that (the boa is in an 18 in high, the python in a 12 in, so the python stays around 85) relies on the pad, which again gets to 72.

Those of you who only use UTHs, how do you get your enclosures above 80?

Btw, using an ExoTerra digital thermohygrometer, so I'm fairly certain the readings are accurate.