Are you talking about an on demand system? I'm talking about a 50 gallon or whatever Natural Gas hot water tank.
Currently have copper running from the basement up through holes in the floor and cabinet to attach to the kitchen sink. Now I'm wondering about running pex up through the holes, or going with something like like below, copper stub outs. Guess the reason I am thinking about this is that the existing lines get beat up a lot from garbage can, recycling can, dish tray being smashed into them constantly.