Quote Originally Posted by The Serpent Merchant View Post
When controlled by a thermostat there is no need for an air gap for the UTH. The thermostat will prevent any heat build up from happening.

Cardboard hides are fine but they will need to be changed regularly to prevent bacteria/mold growth.
Good point about the cardboard hides.

However, I have to respectfully disagree with your first comment. If the probe is not under the tank but inside the tank (ex. on the bottom of the glass) the temperature will be different from the outside, underneath the tank. Also, with a heavy tank and a thick carpet, it would be touching the UTH - not a good idea.
There is a reason UTHs come with those little stickies to raise the tank.
Even if it were possible that a thermostat could prevent heat build up, which I don't agree with, it is much better to have air flow than risk it otherwise. Also not a smart idea to tell someone new to the hobby not to provide an air gap, when it could indeed be a fire hazard. At least that is my opinion.