"Bob Pietrangelo" wrote:
Are you doing this to add a continous loop of hot at the sink? You will
definitely get the hot water quicker, but you will have loss. Your HWH may
cycle a little more than usual.

No loop - I am replacing a 3/4 copper that is in the concrete with a 1/2
inch copper that will run overhead and be insulated.

I have considered a POU small water heater under the sink.