Please help replacing my backflow preventer on my sprinkler system

Discussion in 'Irrigation / Sprinkler Forum' started by mihomeowner, May 27, 2013.

  1. mihomeowner

    mihomeowner New Member

    Messages:
    40
    Location:
    Michigan
    My backflow preventer/pressure vacuum breaker cracked because I didn't get it to last fall before a early hard freeze. Stupid home owner mistake...

    Anyway, I'm trying to figure out to take one of these off and replace it, and I have seen some posts saying it's pretty easy... but I am not sure where to start. Do I need to take a hack saw to this thing to get it off? I see threads everywhere... but tried to take a wrench to them with no luck.

    Some of the threads have teflon tape on them, I would assume these should unscrew.

    Please help!! See attached pictures of my setup.

    Attached Files:

  2. Terry

    Terry Administrator Staff Member

    Messages:
    14,763
    Location:
    Bothell, Washington
    You will need to cut somewhere on that piping, and then couple and resolder.

    The vacuum breaker looks to be threaded into a shutoff on the vertical. That should unthread. If you need to replace the shutoff below it, you will either have to cut more pipe or chip out the brick to allow it to spin off.
  3. mihomeowner

    mihomeowner New Member

    Messages:
    40
    Location:
    Michigan
    Thanks Terry. That is basically what I thought I was going to have to do. Cut one side, unscrew the other.

    Is this copper or galvanized steel? Coming in to the PVB it looks cooper but the downstream the piping is more black. Is this just what happens to old copper pipes? Weird how one side is black.
  4. Terry

    Terry Administrator Staff Member

    Messages:
    14,763
    Location:
    Bothell, Washington
    Copper can turn pretty black.
    You will need to sand that and flux it as you assemble the new fittings before soldering.
    You could use a union on the outlet side. It may help for replacement in the future, though odds are the next new one will be sized a little differently.
  5. mihomeowner

    mihomeowner New Member

    Messages:
    40
    Location:
    Michigan
    The only problem with using a union is, would it make it easier for someone to steal the thing? Thefts of these are on the rise, although mostly from businesses where I imagine the PVB is bigger.

    Anyway, if I don't do a union than a coupling would be the answer?
  6. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

    Messages:
    1,141
    Location:
    South*East
    You will be replacing the valves as they a part of a new device.

    John
  7. mihomeowner

    mihomeowner New Member

    Messages:
    40
    Location:
    Michigan
    John - Yes I noticed all the parts have the valves. It made me wonder why the valves are even threaded on to the PVB
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