UTH's absolutely must have a thermostat to control them. Otherwise they can easily get up to 130 degrees (enough to kill your snake) How are you measuring temperatures? UTH's do not affect the air temperature in the cage so unless you have a probed thermometer you have no way of telling how hot it actually is getting.
Bathing or soaking your snake is never a good idea as it will stress out the animal and remove essential oils necessary for the shedding process.
Also do not buy a thermostat from a pet store as the thermostats sold there are overpriced and do not work very well.
Here are some good ones.
The Hydrofarm, it costs $30 and can be purchased on Amazon, but doesn't regulate temperatures as good as it should. it will do what you need it to do but should be replaced with a better thermostat as soon as possible.
http://www.amazon.com/Hydrofarm-MTPR..._bxgy_ol_img_b
The Herpstat is the best you can get, but has a higher price tag. Herpstats start at $99 but there are more expensive/better models available. they regulate temperatures significantly better than the hydrofarm can.
http://spyderrobotics.com/