Water Regulator - Fall Off Pressure?

I have a Wilkins Model 70 pressure regulator on my house - (city water system). The static pressure (measured at a hose bib 15 feet from the regulator) is 60 lbs, the overnight pressure is 80 lbs (my hose bib mounted pressure gauge has a needle that sets maximum pressure).

I think my regulator is bad (installed 1985) - not because of the overnight increase in pressure (could be thermal expansion) - but because the simplest water use, like flushing a toilet for example, cause a 20 pound fall off in water pressure on the gauge - a fall off in pressure which does not recover until the water demand is over. If the regulator was function correctly - should the regulator increase flow - thus increasing pressure to something close to the static value (over time)?

Wilkins's charts/specifications for the Model 70 indicated that I should only be seeing something on the order of 10 pounds of fall off in pressure.

Any comments?

You have classic symptoms of a "shot" PRV: it does not hold house-side pressure below city main pressure, AND it fails to maintain satisfactory house-side pressure under moderate flow. Replace the PRV

Thank you

Lucky me, the regulator has union fittings - so replacement will be simple. 20+ years is a good service life for a regulator (I think) - and while it can be rebuilt - why, other than saving a few bucks should I go to that hassle - simple solution, buy the same brand/model (for physical fit) and be done with it.....

Thanks for confirming what I suspected.

prv

Your only problem, if you have one, will be if the manufacturer has made the new units with different sized unions in order to save money on materials.