Not having the heater on a thermostat or at least a dimmer is placing your snake in great risk.
A uth does nothing to heat the air and having it on the side of the tank is doing nothing for the snake. It can be removed if you do it slow and easy. However even if you get it mounted to the bottom it is really useless until you get a thermostat or dimmer.
A thermostat is your best bet and I don't mean the options at the pet store. Those are junk. I like Herpstat and they are widely used in the hobby.
Don't think that placing a thick layer of substrate over the uth is a fix to having the uth get to hot. Snake CAN and WILL borrow to get to the heater. Placing a thick later of substrate over the heater will not allow the heat to get to the snake and it will go looking for it. The substrate over a uth should be a 1/4 inch or less.
Do the proper research and set it up correctly. This has been discussed a ton here and there are plenty of threads that you can check out. Also while you are at it Google burned snakes and see what an unregulated uth can and will do to a snake when it is not used properly.
Yes, a probed thermometer can read the temp of the uth. Having a proper tstat will do the same thing. I would recommend skipping the thermometer and getting a IR temp gun. It is far more useful.
If I was you the two items on my shopping list would be a Herpstat and a temp gun. Amazon has plenty of cheap temp guns.
When it comes to a tstat, which is the most important thing you will buy for your snake you should not go cheap. Buy it right the first time so you have piece of mind. http://www.spyderrobotics.com/
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