wrote in message
ups.com...

"I'd also recommend a check valve on the cold water inlet of the water
heater to eliminate the cold system as part of the expansion area and
to
ensure there's no backflow from the heater into the cold system. "

1. The money would be better well spent on beer and pizza.

2. Some PRV's allow for thermal expansion, eg. Watts AUB series.

3. The thing you need to get is a new plumber, Maybe one that owns a
pressure gauge.

kenny b


What I would guess is: The dynamics of the reducing valve maybe too slow in
getting to its steady state regulating position. With no flow the valve is
in a closed position. When there is a sudden flow demand (opening a faucet)
the valve moves opens to provide flow but actually overshoots its steady
state position. For whatever reason it then slowly closes down to regulate
the pressure. It's during that time frame that there is high flow out of the
faucet. In high performance systems, PRV are fast acting with time
constants in the order of 15-20 millisecond. There are many things that
slow down the transient response of these type of valves--in many cases it
is getting the control pressure to bleed down allowing the valve to respond
quickly Usually a damping orifice being too small is one reason.
MLD