Thanks for the info. I have a TC, so my 9 gallon fresh water tank is under the front 'step" area. We added a port so that we could reach in and clean it out. The junk they left in there from installing it was nasty; wood shavings, metal saving and plastic shavings!
Anyway, using your method I can run my hot water heater and collect the warm water and add it right back into the tank. I think I might spend a night in January monitoring the temps and playing around with it in my backyard... best place to test new theories!
I'd LOVE to be able to use the shower during winter camping. Currently we don't use the freshwater system, and the toilet is a port potty anyway.
