Replacing tank on vfd

Discussion in 'Pumps and Tanks Well Forum & Blog' started by greenmonster304, Mar 2, 2012.

  1. greenmonster304

    greenmonster304 New Member

    Messages:
    21
    Location:
    Hampton Bays, NY
    The tank for my vfd started to leak so I want to replace it but I am not sure what pressure to charge the new tank to. I wasnt sure if the vfd tanks get charged differently. Thanks in advance for your help.
  2. valveman

    valveman Moderator Staff Member

    Messages:
    4,549
    Location:
    Lubbock, Texas
    The tank precharge is usually about 30% less than the running pressure.
  3. JPat

    JPat New Member

    Messages:
    14
    Location:
    Johnsburg, Il
    Hmmm. Every VFD we have installed, the manufacturer recommends 70% air pressure to running pressure...Doing the math for you; if your running pressure is 60psi the pre-charge in the tank should be 42psi.
  4. valveman

    valveman Moderator Staff Member

    Messages:
    4,549
    Location:
    Lubbock, Texas
    Hi JPat. Doing the math I think 70% of, or 30% less than 60 is still the same 42 PSI. The real question is why did the tank go bad?
  5. JPat

    JPat New Member

    Messages:
    14
    Location:
    Johnsburg, Il
    Meh, tanks go bad all the time. The rubber that most companies are using is recycled... "Do it yourself" tanks have a high failure rate as well. 5yr warranty on all tanks!!!
  6. valveman

    valveman Moderator Staff Member

    Messages:
    4,549
    Location:
    Lubbock, Texas
    Bladder or diaphragm type tanks only go bad for two reasons. Either they rust through, or the bladder breaks. Most of the busted bladders I see on tanks with a VFD, are from the pump not shutting off when it should, causing the pressure to spike and bust the bladder.

    One of the big box stores has a 32 gallon tank with a lifetime warranty. I guess it doesn’t have recycled rubber.
  7. Texas Wellman

    Texas Wellman In the Trades

    Messages:
    550
    Location:
    SE Texas-Coastal
    "Lifetime warranty"...when it breaks, the life is over!!
  8. greenmonster304

    greenmonster304 New Member

    Messages:
    21
    Location:
    Hampton Bays, NY
    The tank rusted out because it was in a pit that was always damp.
  9. valveman

    valveman Moderator Staff Member

    Messages:
    4,549
    Location:
    Lubbock, Texas
    Good to know. These are the kind of installations that can benefit from a fiberglass tank.

    Yeah "lifetime warranty". Can you believe that? I think the company might just change names every few years to get out of warranties. :)
Similar Threads: Replacing tank
Forum Title Date
Pumps and Tanks Well Forum & Blog Replacing old submersible pump/pressurizing tank vs constant pressure system Jan 9, 2012
Pumps and Tanks Well Forum & Blog Replacing well tank question Jun 8, 2010
Pumps and Tanks Well Forum & Blog Replacing 25yr old captive air tank Apr 20, 2010
Pumps and Tanks Well Forum & Blog Replacing Pressure Tank use same Drawdown Rating?? Jan 7, 2010
Pumps and Tanks Well Forum & Blog replacing septic tank with sewage pump? Nov 22, 2009

Share This Page