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problem with backflow preventer

ray hickethier
ray hickethier Member Posts: 26
in Plumbing
Is there any problem with plugging a dripping backflow preventer?

Comments

  • Hilly
    Hilly Member Posts: 428
    YES. Fix it or replace it.
  • ChrisJ
    ChrisJ Member Posts: 16,315
    A few years back I had one dripping after it was activated. I fixed it by activating it again a few times by suddenly dropping the pressure on the inlet side.

    I guess some spec of dirt or something got in the seal and by activating it again it cleaned it out.

    Don't ever plug the vent.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • ray hickethier
    ray hickethier Member Posts: 26
    Can anyone tell me why I can't plug it?
  • Hilly
    Hilly Member Posts: 428
    Because if it fails you will never know. If you don't know that it is not working then it's just as well you don't have it there.
  • billtwocase
    billtwocase Member Posts: 2,385
    must be a Watts
  • pecmsg
    pecmsg Member Posts: 5,290
    ray hickethier said:

    Can anyone tell me why I can't plug it?

    Like a PRD device the threads on the back flow preventer are there to plumb the water to a safe location. There not there for a plug, nipple and cap, or anything else. That is the visual indication that something is wrong and the cause found and repaired.
  • icesailor
    icesailor Member Posts: 7,265
    Pressure relief valves for boilers are threaded. The threads aren't there for a plug to turn the boiler in to a bomb, they're there to pipe the outlet to a safe drain. Same with BFD's.
  • Weezbo
    Weezbo Member Posts: 6,232
    edited March 2015
    Ray there is a problem with that, anti backflow suppression valves are guaranteed call backs and everyone needs to make a living...lol there is no advantage in plugging the devise. it would make it like any other piece of pipe were you to plug it.if by some chance you are on a well or holding tank , you can add and additional check valve closer to the water source side of the devise , or disassociate the water fill from the boiler ,however , you are then required to do all the maintenance as described in the microscopically small , small print, by the manufacturers of the boiler components and associated devises. thats why our 500$ glasses we just got do not seem to help us see any better than the ones we already had when we went in ...to clarify that, try reading the tag on the boiler relief valve .
  • hot_rod
    hot_rod Member Posts: 23,379
    Is it this type? Usually if you plug them, which is not advised,

    they will leak around the rivets that hold the label on. The rivets are drilled through so it cannot be pressurized if it is plugged on the discharge.

    They are very easy to disassemble and clean. There is a seal between the spool and body that has to be made when pressure is applied.

    Often when they are returned for warranty there is something stuck between that spool and seat. Stuff like rust, teflon tape, solder balls, copper readings, even lime or calcium build up.

    Most brands require a constant 25 psi minimum to "make" that seal. Caleffi brand will seal bubble tight with 20 psi.

    If it sprays or squirts occasionally it indicates the incoming pressure has dropped below 20 psi for an instant.

    Water hammer (hydraulic shock) may cause this, fast acting valves like solenoids, flushometers, wash machine fill valves, etc.

    If you have re-occuring problems with BFDs sometimes adding a check upstream will help, or a water hammer arrester.




    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    icesailor

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