Hi Heavy Metal,
smkettner has a system that recirculates using water from the propane water heater. Pretty slick! His RV doesn't have an enclosed belly.
It also saves him water when boondocking as he can warm the lines to the shower, or the hand basin without water going to the waste tank.
Heavy Metal Doctor wrote:
I also wonder if anyone has considered winter re-circulation:
In water pumping equipment, we circulate the water to keep it from freezing. You can't put in enough pink stuff to winterize it, so we pump it to keep it moving. People talk about freezups of the lines while camping and having to leave water trickling from the faucets -- same principle. This stuff gets operated down well into temps in the teens and all of the lines / pumps are exposed out in the weather. It is a much higher volume, so that might be a factor. Maybe a little flo-jet pump can't hold out against freezing 6 gallons a minute like a 60 GPM industrial pump does.
I might have to do a little test the next time I get a spare electric pump to play with - let it run outside with a barrel of water to see how cold it will continue to work.