On Mon, 18 Feb 2008 19:57:10 -0700, Rick Blaine wrote:
Does the pressure of the hot water rise to 120 psi while the pressure of
the cold water remains at 80 psi?

Water expands when heated... Older systems allow that pressure to go back into
the supply line towards the street. newer systems have check valves.

Hi Rick,

I was wondering why BOTH the hot water outlet and the cold-water inlet had
check valves built into the respective dialectric nipples provided in the
top of the new tank!

Are you saying the hot-water check valve prevents hot water from leaking up
the pipe for efficiency reasons; while the cold-water check valve prevents
hot water from leaking backward into the supply line?

If the pressure is 150 psi inside the tank, what is the pressure the hot
water is coming out? Is it at 150 psi while the cold water remains at 80
psi? I find that hard to believe, empirically.

Donna