Ever wonder why it takes so long sometimes for the hot water to finally start coming out?
Reason Number 1:
Lets begin with the piping layout.
When most homes are built, there are no specific plumbing blue prints to follow, so the plumbers just connect up the piping however the individual doing the job feels like it.
Whatever is easiest often is the only criteria. I’ve encountered tract homes that have identical floor plans yet the plumbing is connected up substantially different.
If your heater is 30 feet from the fixture as the crow flies, you probably have at least 50 feet of pipe.
The simplest plumbing layout would have a pipe connecting from your water heater outlet, running either down to the crawl space or up to the attic, or even under the slab if you have slab floors.
Now add the 30 feet of pipe to the fixture, and the pipe running either up to the fixture or down to the fixture. So you now have at least 60 feet of pipe. However, seldom is the pipe run diagonally, usually following along beams or through walls etc, making right angle turns here and there. The pipe could be 80 feet or longer by the time it reaches your fixture.
So if you do not have an uninterrupted hot water circulating system, every time you use water, you have to wait for the water tom travel all that distance until it gets to your faucet, and worse, has to heat up those pipes too!
But this is only one of the possible reasons.
Understand Flow Rates:
Flow rates and fixtures
The amount of water flowing through the pipe, water pressure and the pipe diameter, is what determines the speed at which the water flows.
The flow rate of the water is most likely determined by the flow rate of the faucet or fixture, in certain areas a pressure regulator outside the home is set to 40 to 60 PSI maximum, especially in Los Angeles areas.
At only 40 psi, a ½” diameter copper pipe 100 feet long would have a flow rate of over 6 gallons per minute, with a velocity through the pipe of over 10 feet per second.
At that rate your hot water would arrive at your sink in about 6 seconds! Large diameter pipes would have even higher flow rates.