I have a terrible "water hammer" effect when the automatic sprinkler system runs and am trying to correct it by adding a PRV or possibly two PRVs (my water pressure is around 95 PSI). Can I add just one PRV on the main supply line that enters the house in the basement? My sprinkler system is tied into that line about 4 feet after it comes into the basement. Or, should I only add a PRV after the point where the sprinkler system tee is located? One more possibility... should I simple use two PRVs with one on the sprinkler system line and one on the main line after the sprinkler system tee? Looking for any advice.

95 PSI is too high for house pressure. Use one PRV and set it back to 60 PSI. Install the PRV on the service line before the branch to the sprinkler system. If that doesn't stop the hammer click on back and we'll build a air chamber,( shock arrester) on the sprinkler system. Good luck, Tom

Thank you... I'll get the one PRV installed in the suggested location on the main line within the next few days.

Great! Let me know if that cures the hammer. Good luck, Tom