sajohnson
New Member
I'm repairing the supply to undersink water filters I originally installed 25+ years ago. At the cold water supply is a 3/8" MIP nipple. There is an older supply line (perhaps from a sink sprayer?) connected to it that has a conical brass>nipple compression fitting (no O-ring). The other end of that supply line was connected to a brass hose barb.. It had begun to leak there. The hose barb fitting is threaded into a pressure regulator, the output of which is connected to the input to the filter canisters with a 3/8" brass adapter.
So: 3/8" nipple > hose > hose barb > regulator > filters.
The 60 psi regulator is not needed since we are on well water and the pressure switch is set at 55 psi max. So my master plan is to eliminate the hose / hose barb fitting/ and the regulator by using a new supply line directly from the 3/8 nipple to the brass adapter at the filter inlet.
Not knowing better, I bought a typical 3/8" comp x 3/8" comp supply line with connectors that fit on a service valve. Needless to say, that did not work -- diameter too large and different threads.
Then I was told I needed a supply line with 3/8" *FIP* connectors -- so I got one. It threads on the nipple but not the brass adapter at the filter inlet -- even though they are both the same thread size and pitch (and the old/existing hose will thread onto both).
Then I realized that the brass adapter has tapered threads -- still the old hose will screw onto it, as well as the nipple which seems odd.
The other issue with the FIP connectors is that even though they work with the nipple, there is a flared brass tube just inside and slightly above the O-ring. The nipple hits that tube before it contacts the O-ring. I haven't put pressure on it yet to see if it leaks but I'm almost certain it will
Bottom line -- 1) 3/8" FIP is correct. 2) I assume I need a brass inlet fitting with parallel threads? 3) That leaves the issue of the flared bass tube. Those 3/8 FIP supply line connectors seem to be intended for a specific use.
Any thoughts and/or suggestions appreciated. Different supply line Different nipple and/or brass fitting?
Thank you!
So: 3/8" nipple > hose > hose barb > regulator > filters.
The 60 psi regulator is not needed since we are on well water and the pressure switch is set at 55 psi max. So my master plan is to eliminate the hose / hose barb fitting/ and the regulator by using a new supply line directly from the 3/8 nipple to the brass adapter at the filter inlet.
Not knowing better, I bought a typical 3/8" comp x 3/8" comp supply line with connectors that fit on a service valve. Needless to say, that did not work -- diameter too large and different threads.
Then I was told I needed a supply line with 3/8" *FIP* connectors -- so I got one. It threads on the nipple but not the brass adapter at the filter inlet -- even though they are both the same thread size and pitch (and the old/existing hose will thread onto both).
Then I realized that the brass adapter has tapered threads -- still the old hose will screw onto it, as well as the nipple which seems odd.
The other issue with the FIP connectors is that even though they work with the nipple, there is a flared brass tube just inside and slightly above the O-ring. The nipple hits that tube before it contacts the O-ring. I haven't put pressure on it yet to see if it leaks but I'm almost certain it will
Bottom line -- 1) 3/8" FIP is correct. 2) I assume I need a brass inlet fitting with parallel threads? 3) That leaves the issue of the flared bass tube. Those 3/8 FIP supply line connectors seem to be intended for a specific use.
Any thoughts and/or suggestions appreciated. Different supply line Different nipple and/or brass fitting?
Thank you!
