[brucepick]

Best of luck with the cartridge heater.

I installed one. Determining the hose routing is pretty critical. The heated output water needs a continual upward travel to the head because it moves by convection/siphon, not by pump action. Any upside-down "U" shape in the hose disqualifies that hose as a path for your heated water, because an air bubble will likely exist at the top of the U. Just FYI.