Need help with slamming check valve

Discussion in 'Pumps and Tanks Well Forum & Blog' started by Gabe1, Mar 20, 2011.

  1. Gabe1

    Gabe1 New Member

    Messages:
    4
    Location:
    CT
    Hello
    I recently replaced my water tank(no bladder), check valve,sniffer valve and switch,
    I have a Air charging system (submersible about 100 feet with a check valve at the pump and another before the tank, 1/2 HP 115v 3 wire control box).
    This was a straight swap basicly nothing changed.
    The problem that I am having is the loud slamming only when the pump starts,my first guess would be the new check valve before the tank!!!

    Anything I should try before I buy another check valve?

    The switch is a 30/50 and is set at 32/55

    Attached Files:

  2. Waterwelldude

    Waterwelldude Well driller,pump repair. and septic installer

    Messages:
    303
    Location:
    Texas
    Check to make sure you didn't screw the nipple that the pressure switch sits on to far down. If it is too tight or to far down in the check valve.
    The stopper in the check will hit the nipple.
  3. Gabe1

    Gabe1 New Member

    Messages:
    4
    Location:
    CT
    Thank for you reply

    I did check the nipple before install and its sitting 1/8 above the last tread.
  4. Waterwelldude

    Waterwelldude Well driller,pump repair. and septic installer

    Messages:
    303
    Location:
    Texas
    If i understand what your saying, (that there are only 1/8" of thread still showing)
    That sounds like it may be a little deep.
    If you don't get any other suggestions on this, try backing it out about 3 threads and see what happens.
    You may have to reapply teflon tape to the nipple.
  5. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,136
    Location:
    Maine
    Get rid of the check valve at the tank, you don't need it.
  6. Waterwelldude

    Waterwelldude Well driller,pump repair. and septic installer

    Messages:
    303
    Location:
    Texas
    With his type of set-up, the check has to be there. Without it, the air system will not work correctly.

    If he had a bladder tank set-up, without a sniffer and a bleeder in the well, you would be correct.
  7. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    3,932
    Location:
    NW Ontario, Canada
    Do you get the same loud slamming regardless of how long the pump is off between cycles? What happens is that the column of water is like a freight train that has been decoupled from the check valve to just below the bleeder. The amount of speed and inertia it gains depends on the distance between the check valve and the bleeder. As the gap closes, the air compresses until it exceeds the pressure in the tank and the valve opens. Air can move faster than water through the short distance to the tank and the water behind it shakes things up.

    The check valve in the pump should normally hold the column of water up to the level of the bleeder, but a check valve holds better if it has more pressure to hold against. When the check valve in the pump does not hold the column of water, you get more air into the pipe and the freight train gets a longer run and can hit harder.
  8. valveman

    valveman Moderator Staff Member

    Messages:
    4,426
    Location:
    Lubbock, Texas
    Air on the backside of the check valve usually cushions the opening of the check. Makes me think the water IS NOT draining back to the bleeder as it should. Then you have no air for a cushion and the water hammers the check open.
  9. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    Be sure the schrader valve is opening when the pump shuts off, put some water on it and see if it sucks in. No suction at schrader, no opening of bleeder.

    Maybe your old tank was ok and you need to fix the bleeder.

    You could actually install the bleeder right there on a pipe extension and take it to a drain. Then you know they work. It take a lot less air to keep the tank full than you think. Mine work with about 10" of 1" pipe.
  10. Gabe1

    Gabe1 New Member

    Messages:
    4
    Location:
    CT
    This is cool
    I just sit back and absorb all the good hints.
    I think valveman and ballvalve are on the ball I check my schrader valve and it's not sucking air at all.

    I was told in another forum that all schrader/sniffer valves are alike but after researching a little more I found that you need a sniffer with a weak spring
    I need to order one of these special valves and see what happens .
    I will update as soon as I get it.

    Thanks
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