Presumably your water heater was installed with a T&P valve which will
release when the set temperature or pressure is exceeded thereby
avoiding a rupture. These are required in every area I've lived in and
are mounted on the water heater.

An expansion tank is worth adding since it will prevent the T&P valve
from opening, and spilling water, should the pressure be exceeded. I've
had pressure regulators (Watts Regulator was the manufacturer) since my
city saw fit to supply water at 100 psi+ rather than install adequate
size water mains for years with no problems without an expansion tank.

RB

John Gregory wrote:
I posted here last week and would like to get some additional info please.
My Village is kicking up the water pressure next Friday. They've given
anyone who asks, a free reduction valve. Pressure is currently 40psi prox
and will increase another 35 - 40 according to the Village. I was all set to
solder this puppy in place when I read the brochure and saw the
recommendation of an expansion tank. I know three neighbors who have had the
valve installed; none added an expansion tank. These home are about 30 - 35
years old. My next door neioghbor - who built 800 homes over the past 25
years - says he doesn't think he's going to even add the valve. His house is
less than 10 years old though. I'm more concerned about having a closed
system with the threat of thermo pressure. I guess if I DON'T puit that
valve on and pressure builds, it has releaf by flowing back past the meter.
Apparently it can't do that if I put that valve on.

Q1) Is this right?

I keep my water tank at about 125 - 130. It has a pressure releaf valve on
it. I'm of the opinion that most people feel the probablility of needing an
expansion tank is pretty remote. Give these conditions...

Q2) Would you think they are right?