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.