thermostat problems

You can also get IR temp guns at most places that sell tools as well... Harbour Freight, Sears, Lowes, some auto parts stores, etc...

I would agree with Vypyrz; if you have the temperature probe taped to the underneath side of the UTH it is going to register much cooler then the top side. Either tape the probe to the bottom of the tank over the UTH or between the UTH and the bottom of the tank.