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Thread: Issues with connecting new FNS Plus

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    Issues with connecting new FNS Plus

    Hello everyone, my first time posting but have read advice on the site for years. I'm kind of at a cross-roads with our new filter tank and got tired of Leslie's trying to up sell me on things I didn't need. Long story short, I had a leaking crack on my old american products titan filter, so I purchased a new fns plus to replace it. Disconnecting old filter was easy but I seem to be missing something on connecting the new one. I "think" I know the issue but I'm not sure what parts I need (a simple pvc union or adapter kit). My valve is a Pentair SM-20-2 and I confirmed it's compatible with the fns plus.

    I'm not even sure if I'm using the correct terminology, but it seems the union? on my valve is too small to connect to the bulkhead of the new fns plus? I'm hoping I don't have to replace the whole multiport valve or cut out the pvc from the current valve and can find a simple "adapter" for it.

    Here's a pic of the pvc from the back of the valve:





    and here's a pic trying to connect the pvc/union? from the valve to the new fns filter bulkhead? Seems the threads/bulkhead is too large b/c the ports on the old american products filter were smaller.


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    cowboycasey's Avatar
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    Re: Issues with connecting new FNS Plus

    Welcome to TFP

    The filter should have come with the union set to connect the new filter to the old system. you will need to cut the old union off and glue on the new union.. If the pipe is not long enough you can use a coupler just like they did on the bottom connection you have (the one that says inlet)

    I hope this helps
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    Re: Issues with connecting new FNS Plus

    It's not hard, you just have to take your time, think about what your doing, don't glue any of the pieces until you know the way you plan on connecting it all will work, it helps to have a new filter, because it's easy to move around to help position, or guide, in order to connect to the fittings your ready to glue to the backwash valve, place the filter where you want it to be, then figure out what you need to cut and configure from the pump to the filter valve, then figure out how to configure the return line to filter vale, then from there i would glue the last two fittings that connect to the backwash valve and slide the entire filter up to the wet glued pipes and push them on the valve and your done.

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    Re: Issues with connecting new FNS Plus

    That won't fly- Pentair does not want the ID of pipes glued/welded.

    Get a multiport or push pull valve & use the unions on the new valve assembly. The included I ring & Union will hold the valve.

    The weld /solvent it looks like you applied may have compromised fit for o-ring on valve.

    Either way easy fixes.

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    Re: Issues with connecting new FNS Plus

    Part number 261152.

    2 in. MPV, for FNS, FNS Plus & NSP filters [SM 20-2], 7.5 in. Centerline

    Probably best to replace the valve. The existing valve has the wrong connectors and will not work. Trying to replace the connectors is probably not worthwhile especially since it's an old valve.

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    Re: Issues with connecting new FNS Plus

    Thanks everyone for the replies. I had a feeling I might need to cut the pipe coming from the valve. I think I replaced my old push pull valve with the current Pentair 20-2 multiport that is on there now just a few years ago. Is the 20-2 model an old/out-dated multiport valve? It can't be more than 5 years old but maybe the pool company sold me/installed an older model at the time?

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    Re: Issues with connecting new FNS Plus

    Sm-20-2 is the correct valve. Don't know why the connectors are the wrong ones. Maybe they were replaced to fit your old filter. In any case, I don't think that you will be able to make the old valve work.

    Even if you can find the correct parts, I don't think that you have the room on the top connection to replumb it. Instead of spending money and time trying to get the old valve to work, I think that you're best option is to just get a new valve.

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    Re: Issues with connecting new FNS Plus

    I read his post as saying he also had a new pentair valve "with" the new filter, but wanted to use the multi port from the AP filter that's still plumbed in, i was suggesting he cut the old valve out, as the bulk head nuts on the valve are AP, and obviously not going to work, there's no question he was banking on the new filter sliding right up to that valve and hooking right up, after he discovered it was not going to do that, is why he posted this to find out how to keep the old valve, he seemed apprehensive about the unexpected possibility about having to plumb in a new pentair valve to the new filter, i was actually trying to encourage him to cut the old valve out and plumb in a compatible pentair valve that i thought he had in addition to the old one.

    If i had to make the old valve work i could, as long as the top pipe off the valve happened to line up to the new filter, with a pentair bulkhead union in place of the AP one, I'd ram-bit the pipe out of the 2''couplings where i had cut the old AP bulkhead union off at, glue in the pentair union, and adjust the bottom pipe on the valve up or down if it didn't line up with the bottom bulkhead on the new filter, blah, blah ,blah.

    I used to be a warranty rep for American Products, when there was an actual company called "American Products"

    I just want to be clear that i was not suggesting he tie into the old valve with the new filter, my post was more of a response about plumbing in general, using a new Pentair valve .

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    Re: Issues with connecting new FNS Plus

    After i attach a push pull valve to the filter with the bulk head unions, i have to glue the pump and return pvc pipes, to the slip sockets on the pump, and return ports, in front of the push pull valve.

    I didn't mean trying to glue pipe into the bulkhead fittings on the filter, in case you were referring to me.

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    Re: Issues with connecting new FNS Plus

    Quote Originally Posted by cowboycasey View Post
    Welcome to TFP

    The filter should have come with the union set to connect the new filter to the old system. you will need to cut the old union off and glue on the new union.. If the pipe is not long enough you can use a coupler just like they did on the bottom connection you have (the one that says inlet)

    I hope this helps


    I think I'm going to try and make it work with the current valve. If I try to cut the pvc coming out of the multiport, the question is do I need this bulkhead union, part #271096

    271096-2.jpg


    and use the coupler with that to connect to the fns plus filter?

    Or do I need this valve adapter kit instead, part#270100?

    270100-3-1.jpg

    They look similar to me but I'm sure they're very different parts. Thanks again everyone!

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    Re: Issues with connecting new FNS Plus

    did some research and these parts look to be the same. Anyone know why they have different part #s? Still not 100% sure if they'll work

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    Re: Issues with connecting new FNS Plus

    Once you cut off the old connectors, will you have enough pvc to be able to glue on the new connectors?

    Maybe contact Pentair to confirm part numbers.

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    Re: Issues with connecting new FNS Plus

    The white ones are from the Pac-Fab era, before pentair aquired, or bought them out, way back when there filter tanks were green fiberglass, with white fittings, as far as the sand filters were concerned anyway.

    I would suspect they are also model year and month specific, like use this part if your filter was made before or after this date, etc.

    The black ones are what you will want to use in your case.

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