visitherm heater.

Perhaps your room temperature is 78, therefore even though your heater is set to 72 it can only heat the water not cool it .. maybe??
 
I have a Stealth and I have to keep it set at 75 to keep the tank at 81. This is my second stealth. The first one just quit working altogether...
I use a Checktemp digital thermometer. They are supposed to be accurate to +-.5 degrees
 
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