Really?Animal interfering with the probe notwithstanding, wouldn't direct contact with the pad read hot? The tub's floor is not a perfect conductor (obviously since its designed to insulate the interior) so the heat generated by the pad is partially absorbed and dispersed by the floor itself resulting in a lower actual temperature on the tubs interior surface, no? I feel like its similar to measuring a car's horsepower at the crank vs at the wheels (I figure a mustang fan would appreciate the analogy).