Save your old Parts when making a repair!
Recently we repaired a Watts 909 2″ RP. We replaced Check 1, Check 2, and installed a rubber kit for the relief valve. We noticed that the O-ring on the brand new relief valve repair kit looked just a hair larger than the original one found in the Backflow Prevention Assembly. We are speaking about the O-ring that fits in the groove on the relief valve stem. It was new, so we put a little bit of lubricant that came with the kit on it and fit it all back together. The Assembly tested fine and we were down the road.
We were called back a week later and notified that the assembly was in a wide open dump out of the relief valve. This is in an outside location.
We returned to the repair and upon taking apart the relief valve noticed the new O-ring was binding. We searched through our parts bag and could not find another O-ring to finish the repair. We did have the Box of old parts taken out of the old relief valve. We were grateful to find the exact O-ring that came out of the Assembly, and It looked in great condition. We carefully lubed it up and installed it. The Backflow Prevention Assembly tested fine again, and we feel like we found the issue that was causing the relief valve to dump wide open. We have another happy customer.
Remember to save your old parts, They could come in real handy when the new repair kit comes with an O-ring out of tolerance.