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Thread: How to replace Pentair FNS Plus Manifold

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    How to replace Pentair FNS Plus Manifold

    Opened pool about a month ago and the water still have lots of small particles especially near return lines. I also see lots of sand (probably DE) on the floor. I decided to open the filter (never done this by myself before) and found that plastic on top of the grid has some cracks. I assume this is the top manifold and I believe the cause of my problem. I found replacement part, but canít figure out how to do you replace it. Do I have to unscrew two plastic hex nuts and lift the grid out? Does anyone have instructions how to do it?

    Thank you,

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    Join Date
    May 2007
    South Central NJ

    Re: How to replace Pentair FNS Plus Manifold

    Pull the grid first.

    Unscrew the two nuts. Lift the manifold up.

    I suggest taking the opportunity to hose off the panels too. Sounds like it hasn't been for some time. I also suggest a soaking for the panels after in a clean 32 gallon trash can, full of water and a 1/2 box of of cheap, powdered dishwasher detergent.Two hours right side up, two more upside down. Inspect them closely for hose and broken framework. Replace as needed.

    Note where the 1 short panel is in the spiral. The others are all the same, larger size. This should be done annually, by the way.

    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

  3. Back To Top    #3

    Re: How to replace Pentair FNS Plus Manifold

    Took it apart and followed your advice. Iím now waiting for replacement manifold to arrive and I also found some grids with soft edges that are also being replaced. I found that one of the grids is partial size(looks like half) and unfortunately I didnít notice where it was.
    Is this the one that goes closest to the center of the template?

  4. Back To Top    #4

    Re: How to replace Pentair FNS Plus Manifold

    Never mind. I think I found how it works. The bottom template shows exactly how to put grids back. Duh!

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