On Oct 8, 8:41*am, "Vaughn Simon"
wrote:
"Dave, I can't do that" wrote in ...

I have two separate runs of hot water in my house and to use two of
these commercial units would cost almost 500-bucks.

The systems that I have seen depend on natural convection. *The main hot water
pipe is ran under the floor, and a smaller return pipe is ran along the ceiling.
Any of these systems are huge energy wasters.

Vaughn

That's why I favor the one that pumps the cold water from the hot line
into the cold line only when you push the button. The 'hot' line
doesn't stay hot when you don't use any hot water.

It wastes a small amount less energy than just running the water
because the 'cold' water you're pumping into the water heater is
(probably) warmer than water drawn fresh from the mains, or from the
well.

Dave