CrazyBall: I think everyone here has pretty much covered where to place your UTH, so I'll hit a couple other points that apply.

Absolutely, as Aaron & JohnJohn said, get a temp gun!  These are used to detect surface temperatures, and when setting up a new cage (or changing any heat sources), this is key to making sure that your cage is safe and you don't burn your snake!  Pretty much any other temperature measuring device will tell you more about ambient temperatures, which are important, but it is the surfaces your snake comes into cantact with that could potentially burn it.  I have a temp gun, and I love it.  Mine was a gift... which I directed my husband to get me from here: http://www.tempgun.com/main.html ;) ...mine is the PE-2, but it's older, so it doesn't look quite as flashy as what their site now shows (the laser pointer is definitely worth it!!).

Further, get a good, reliable method of measuring ambient temperatures & humidity within the cage.  These are key to determining that the environment in the cage is appropriate for your snake.  As several other keepers I know from other forums are fond of saying: “when it comes to temps & humidity, know, don’t guess!”  I have a couple of digital thermometer/hygrometers (I actually only bought the second one because I couldn’t find the first one for a while), and I love them!  Mine are made by Fluker’s and are probably available at any pet store that even attempts to sell reptile supplies.  The Fluker’s website is below par in my opinion, but this is the closest I can find to a direct link: http://www.flukerfarms.com/temperaturegauges.aspx – ignore the first 4 items listed, and only look at the last item, as that is what I use & love.  You can find a bunch of places that sell them if you Google search “Fluker’s + thermometer.”  (Do not, DO NOT use those silly little dial display thermometers & hygrometers that adhere to one fixed location in the cage!)

Finally, please get a thermostat to regulate the UTH!  There are many available, from rather cheap to quite expensive.  Even the cheap ones are perfectly acceptable; you just have to measure everything yourself & not rely on the printed-on-the-plastic-housing settings to get the temps where you want them! Once you have the settings figured out, the cheapie thermostats will maintain what you set.

Whatever you end up using, you need to measure ambient temps & humidity, and surface temperatures at several different times of day, in several different locations within the cage & re-check them seasonally, or whenever you change something in your setup.  I say “seasonally” because most of us see some very noticeable shifts in temps & humidity between the winter and summer months in our homes, and in our animals’ cages – so even if you change nothing, you should be checking your temps probably about every 3-4 months anyway, just to make sure everything is staying where you think it is.  This may sound like it is “overboard,” and I can guarantee you that there are plenty of people who do not put this kind of effort into checking temps & humidity, and their animals survive just fine, but all of these things I have mentioned (temp gun, digital thermometer/hygrometer, thermostat) will help you to better provide for your pet’s needs & good health! 

Best of luck & happy herping! :)

This question has had no activity for 14 days and will be closed by an administrator unless the original poster takes action.

Recommended Action: Points awarded

An administrator will select responses and assign points at their discretion.

Original poster, please close this question out and assign points. If you have any further information in the resolution of your problem, please post it here so that others may learn from it.