[Greenbuilding] Hot water return

[Gennaro Brooks-Church]

I'm doing a plumbing job and wondered if anyone had opinions on hot
water returns.
I'm getting a lot of (traditional) plumbers praising the use of a hot
water return because you always have hot water in the pipes, thus you
have hot water immediately when you turn the faucet on.
But, and here is the green part, they claim that this means less water
is wasted because you aren't waiting for the cold water to flush out
of the pipes like in a non hot water return set up.
BUT, and the plumbers claim this is not a problem, what about the
energy wasted keeping the water in the pipes hot?

With a hot water return you have saved water but extra energy used to
keep it hot. You could reduce the wasted heat by insulating the pipes.
Without a hot water return you have wasted water but no energy used to
keep it hot. Some plumbers' answer to this is that energy is wasted
when you have to reheat the cold pipes.

Has anyone looked into this and concluded anything?

Gennaro Brooks-Church
Cell: 1 347 244 3016 USA
www.EcoBrooklyn.com