On Mar 16, 11:28*am, wrote:
On Sun, 15 Mar 2009 17:14:08 -0500, Speedy Jim



wrote:
Bert Byfield wrote:
I've got a basement full of old half-inch copper pipe, and some of it
needs to be replaced. I want to do repairs in 3/4" pipe but I'm
wondering if that will cause problems with the water changing pipe
sizes on its way to an outlet. Can I do this?

It will cause a problem if there are long runs on the Hot side.
3/4" pipe has roughly 50% more area than 1/2", meaning that
50% more volume of water has to be drawn from a distant faucet
before Hot water arrives. *That may be trivial or it may be a
real pain in the neck.

That's why they sell foam pipe insulation !!!!!!

Foam pipe insulation will only cut the hot water wait time by an
insignificant fraction of the current wait time.

Wait time is driven by hot water flow rate to the fixture and volume
of cold water sitting in the hot water piping to the fixture. Volume
of cold water in the hot water piping to the fixture is determined by
run length & pipe size.

Typical hot water pipe insulation will reduce heat loss while the
water is being delivered but it wont keep it hot forever (overnight)

cheers
Bob