I'll be moving my gas water heater from the front of the house to the oposite side in the back soon....I'm doing a 2-story addition and this move will put the water heater about 20' closer to the main points of use.
Downside, the kitchen, which is in the front and only a few feet from the water heater will now be about 45' from the water heater.
Once the water heater is moved...we also move the washer and dryer....so the only hot water loads in the kitchen will be the sink and dish washer.
The existing line from the front to the back is 3/4" copper.
From the point of where I will T off the new hot water supply to go to the kitchen, I will have about 30' of 3/4" pipe.
So when I turn on the kitchen sink facet....it will have to run 1.45 gallons of water out the facet before I get hot water....1.45 gallons is the volume of water in that 30' of 3/4" pipe.
If I replace the 3/4" pipe with 1/2" copper pipe, I reduce that volume from 1.45 gallons down to 0.64 gallons.....
In other words....the 1/2" pipe will be less than half the volume which means it should be less than half the time to get hot water....
Additionally, the reduced surface area of the 1/2" copper pipe means less heat loss. So, with proper insulation, the water should stay warmer in the pipe longer.
Looks like I'll be changing out that pipe this weekend....
Even if you are on the right track, you will still get run over if you just sit there.