No termometers in my racks either. I check with the temp gun an a regular basis. I also heat the room so the ambient temps stay good. You stated that you have occasional problems with the heater in your house malfunctioning. I would say just having the accurite outside you will know if the ambient room temps drop due to a heater failure and will know it will be cooler on the cold side of the tubs. My cool end tub temps always are about 4 degrees warmer than the ambient room temp. SnakesRkewl´s advice is good.