I have a Honeywell D05 pressure reducing valve that was installed 5 yers ago when I had a new water line from the street to a 56 year old house in atlanta.
My garden hose on the front spigot was writhing like a snake so I screwed on a pressure gauge: Yikes.... 140 PSI.
While I was at it, i hooked the gauge to the deep sink and measured pressure in the house from 90-140 PSI, suspected the PR
valve and looked up how to adjust. When I sdjusted according to instrutions, it would not hold pressure varied from 20 psi to 110 psi, behind the valve.
I suspected that crud in the city supply side from periodic city repairs of old water lines was the problem.
Google search, found that there is a "repair kit" for my valve.... would have bought from a plumbing supply place online for about $25-30 but dared to try Ebay first. Lucked out! Bought one delivered for $11!!!
The "kit" included a new filter and the nylon insert/basket, gaskets, brass washer. Turn off the pressure. Loosen the lock nut and adjusting nut counterclockwise. Drain the house side line by opening a faucet in basement below this elevation... or have a small piece of foam to plug the pipe and place a bucket under the valve when you take it out. Screw off the body with a stillson pipe wrench... mine just came off easily. Wire brush the krud off the spring and spring end, pull out the old basket with a pair of screw drivers as levers, push in the new one... the spring and end cap must be placed into the body and then the basket with gasket and washer. I found that the whole body/spring and basket must be inserted together and screwed in. To adjust: open the valve (with gauge downstream - this was like $8 at Home D) .... turn adjusting nut clockwise to bring pressure up to 55-55 lb. Tighten the lock nut while holding the adj. nut. Factory is 50# per mfr. website. Whole install took maybe 30 minutes, max.
If a plumber did this for you it would be $90 for the valve and probably $150 for the trip and install. Save yourself the $. Good luck, Paul