hi
As much as everyone raves about under the tank heaters, I myself living in a cooler climate find they surely warm up a bit of floor but do nothing for abient air temp. Especially here in Canada.
I don't think ambient air temp should be ignored. As in nature no floor is warm while the air remains very cold, like it gets here when I use only UTH.
I have found I have to use a heat lamp with a UTH (both controlled with thermastats) when housing snakes in aquariums to get the temp proper.
bmm