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Thread: Is my expansion tank dead?

  1. #1
    DIY Junior Member pigrew's Avatar
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    Question Is my expansion tank dead?

    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. #2

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    bladder or contact tank? you set the air pressure in a bladder tank when it is empty.

  3. #3
    Retired Defense Industry Engineer jadnashua's Avatar
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    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.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  4. #4
    DIY Junior Member pigrew's Avatar
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    Quote Originally Posted by mikeplummer View Post
    bladder or contact tank? you set the air pressure in a bladder tank when it is empty.
    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. #5
    Moderator & Master Plumber hj's Avatar
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    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.
    Licensed residential and commercial plumber

  6. #6
    General Engineering Contractor ballvalve's Avatar
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    Never saw a bladder tank last more than 4 to 6 years. See the stickies.

  7. #7
    DIY Junior Member pigrew's Avatar
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    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. #8
    Moderator & Master Plumber hj's Avatar
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    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.
    Licensed residential and commercial plumber

  9. #9
    DIY Junior Member pigrew's Avatar
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    Quote Originally Posted by hj View Post
    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.
    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. #10
    Moderator & Master Plumber hj's Avatar
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    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.
    Licensed residential and commercial plumber

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