Max basking temp vs Thermostat setting

[Cam]

Alright, so, I bet someone's covered it but I've done a few searches and I can't find what I want.

I'm using a glass tank. Originally I was under the impression that a UTH (Flexwatt) should be used with a felt (Repticarpet) liner under the substrate to prevent the snake from contacting the hot glass and hurting itself. I started thinking that didn't sound right - if your thermostat is set at 90 degrees it won't hurt the snake, and even if it gets uncomfortably warm, the snake can move. Anyway, that leads me to a second point of confusion; do you base your thermostat setting on the temp of the heater or the temp where the animal will actually be? I see a LOT of recommendations to put the probe right on the tape, particularly in rack systems.

I'm housing a coastal carpet, and if I stick the probe to the glass, set the thermostat to 90 and then cover it with substrate (reptibark currently) then the warm side stabilizes at around 85, measured right on the top of the substrate. The only way I can get a warm side temp of 90 is to crank the thermostat up to 96-97 degrees. So, fine, no problem - BUT, does this mean the glass is now going to be warm enough to harm the animal if she comes in extended contact with it? My gut says no freaking way, given that 97 is like human body temperature. I'd think that as long as it stays under 120, burns are almost impossible, but, I'm new at this so I thought I'd make sure.

Thanks!

[Cam]

Alright I think I answered my own question so for anyone finding this via search:

Probe location - folks recommend having the probe outside the tank so the animal can't disturb the probe and move it away from the heat source, resulting in an unsafe overheating of the heater.

Max Basking - Still don't know, but 120F on the thermostat setting lets the glass get hot enough that it's uncomfortable for me to touch.

For my setup I discovered that even with the thermostat at 110F, the hot end of the tank still only got to 85, so I added another 15" run of 11" wide flexwatt to the side of the tank. Hopefully that takes care of it. Part of my problem is the 1" or so of reptibark substrate is a pretty good insulator. Having the side of the tank warm as well should bring up the ambient nicely. I hope.

[Cam]

Oh and it doesn't matter how warm your heater itself gets (within reason of course). You set the thermostat to whatever arbitrary temperature you find that results in the correct basking temp inside your viv. Makes sense.