On 11/20/2015 4:48 PM, Walter E. wrote:

I installed a pressure regulation valve in my city water supply because
city pressure is 120 psi. This turned my house piping system into a
"closed system" with no place for the pressure and added volume to go.
This results in water pressure of 150 lbs, which damages my appliances.
Turns out that I now need an expansion tank to absorb the volume and
pressure created by the water being heated. The plumbers I talked to
cannot agree on what I should do:

I have one water HEATER each to supply water to the front and rear of
our home (2 heaters). Both water HEATERS seem to be connected by pipes
to ONE water SOFTENER that supplies both areas (front and back of the
house) with hot, soft water.

How do I install the water heater expansion tank(s)?

Do I install one small expansion tank at one of the heaters, based on
the specs for that heater only (40 gal and 40 lbs pressure), or should I
install a larger expansion tank at the first water heater to allow for
the second and more remote heater, or should I get two small expansion
tanks, one at each heater?

Both heaters are 40 gal and the house pressure is set for 40 psi.

I don't think it matters, one large one or two small ones. I'd probably
opt for two small ones.