On Feb 7, 9:02*pm, wrote:

BIG SNIP

I'd venture to guess this is an older house and that PRV is now
superfluous.


I think that since the OP has an adjustable PRV it is NOT
superfluous.

My parents house has a PRV just outside the house, kitchen sink.
The house was built in 1959 and in those days water heaters (in SoCal)
did not have TP valves.
In this case the original PRV is superfluous.

In my house I installed a Watts pressure reducing valve & a Watts
dual check valve (backflow prevention), the city only requires hose
bib vacuum breakers but my plumber & I figured "what the hell, let's
do the whole house".

Thus I have a closed system......I throttled the city water pressure
down to ~65 psi from about 75+ to reduce water hammer effects. Jay
R. Smith Mfg. Co suggests in their tech info on water hammer to make
sure that water pressure is 65 psi max.

I did as they suggested; distributed water hammer arrestors & 65 psi
max and water hammer is not evident.
But now I no longer have "firehose" performance on my garden hoses. :
(

I chose not to install an expansion tank per discussions with my
plumber, I installed a 75 psi PRV to allow the ~.5 gallon (max)
daily water. Unfortunately the occasion quick shutoff (ball valve
garden hose or lawn sprinkler valves) cause the 75 psi PRV to
activate & the 65 psi city pressure would not allow a re-seat.

I replaced the 75 psi PRV with a WATTS 530C 3/4" ADJUSTABLE PRESSURE
RELIEF VALVE.
By boosting the relief pressure to about 85 psi I get thermal
expansion relief but no "gushing dump".

I believe that this long explanation may describe the OP's
circumstances and why his adjsutable PRV should NOT be plugged.
It appears as though it is serving to relieve the thermal expansion in
his house since "Water does come out of the relief valve from time to
time and gets things wet in the area".

but who knows?

cheers
Bob