Is my expansion tank dead?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by pigrew, Jul 27, 2012.

  1. pigrew

    pigrew New Member

    Messages:
    11
    Location:
    West Lafayette, IN
    Hi,

    I've noticed that (1) Air doesn't come out of my expansion tank when I press in the valve core of the Schrader valve and (2) When I try to pump up the tank with a hand pump, no air goes into the tank. I was doing the pumping while the water pipes were pressurized. The water in my house has about 25 grains of CaCo3 (and I installed a water softener last month). The system pressure is around 60 psi (no pressure reducing valve that I've found).

    I think that the tank is about fifteen years old. Do I need to replace the tank? Or am I improperly operating it?

    Thanks,

    Nathan
  2. mikeplummer

    mikeplummer Plumber

    Messages:
    190
    Location:
    Ontario, Canada
    bladder or contact tank? you set the air pressure in a bladder tank when it is empty.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,801
    Location:
    New England
    At 15-years, it may be dead. If you knock on it and it sounds solid (klunks rather than rings), it's full of water. As said, to adjust the air in the thing, you need to shut the water off, and drain the pressure from the pipes, then pump it up to around the static water pressure (in your case 60psi). If it doesn't hold or water comes out, it's shot.
  4. pigrew

    pigrew New Member

    Messages:
    11
    Location:
    West Lafayette, IN
    Bladder tank; It is a ST-5.

    I wonder if my pump is just incompatible with the tank's valve, the plastic of the pump's head bumps into the tank, and perhaps prevents the valve to be opened enough for it to be pumped up.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,230
    Location:
    Cave Creek, Arizona
    1. as long as water does NOT come out of the valve when you depress it, the tank is intact.
    2. You have to remove ALL water pressure from the system AND leave a faucet open while you pump air into the tank.
    3. You cannot overcome the water pressure when adding air.
  6. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    Never saw a bladder tank last more than 4 to 6 years. See the stickies.
  7. pigrew

    pigrew New Member

    Messages:
    11
    Location:
    West Lafayette, IN
    The tank was quite dead, and has been replaced. I think that some rubber, or perhaps sediment, was blocking the Schrader valve and the inlet, so that I could not pump up the tank, but also water had not entered the tank. Once I depressurized my water lines and tried very hard to inflate it, the whole mess broke apart and I heard water filling the tank.
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,230
    Location:
    Cave Creek, Arizona
    Your diagnosis could be faulty. The diaphragm may have been stuck to the top of the tank because of no air pressure. When you "popped it loose" it woud have gone to the other side of the tank. Then when you turned the water on, it WOULD have entered the tank pushing the diaphragm back. UNLESS air came out of the water inlet when you pumped air into it, the tank may NOT have been defective.
  9. pigrew

    pigrew New Member

    Messages:
    11
    Location:
    West Lafayette, IN
    Good point, however I think that I misspoke slightly. As I was pumping in air, there was a point that the pressure went back down to zero..... and then I gave up at turned on the water. I hadn't taken it off of the plumbing at that point, so I can't say if it had been filled with water or not. Probably it had been, and the trickle was when the water was replacing the air that I had pumped in.
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,230
    Location:
    Cave Creek, Arizona
    quote; As I was pumping in air, there was a point that the pressure went back down to zero

    That could have been the point when the bellows became unstuck and thus the pressure dropped, until you started to fill the entire tank.
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