R RTR AC Members Oct 5, 1998 5,806 0 0 Braddock Heights, MD Mar 27, 2005 #11 It is not the cool-down that is important, it is having the power off while the heater is exposed to air. It overheats then, and when water hits it it cracks or shatters. Just unplug it before the water change.
It is not the cool-down that is important, it is having the power off while the heater is exposed to air. It overheats then, and when water hits it it cracks or shatters. Just unplug it before the water change.
