OK so I ran 1qt. cold water which is 1/2 pex and it took 13.21 sec.I replumbed the entire house when I remodeled 12 years ago. Used type M copper pipe throughout.
Some simple arithmetic shows that to get hot water to the kitchen sink - or to a 1/2 bath at that end of the house we are heating 10 lbs of copper pipe each time we wash our hands or rinse a cup.
I am thinking about replacing the copper hot water pipe with Pex. The heat loss would be much less so less energy used, we would get hot water sooner and we'd use less water.
The water lines are exposed and run across the joists in the cool basement so it would be an easy job to run the pex in the same pipe hangers that the copper is in.
I have the skills and the pex tools so it would be afternoon's work and maybe $60 in parts.
I'm thinking it's worth doing but what says the brain trust here?
I then ran hot water and it took 13.49 sec. and it was hot in 6 sec.
My 3/8 run is 9 ft from heater.
Used same faucet and it has 1/8 in hole at exit.