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Pentair FNS Plus filter

Posted by standfas (My Page) on
Fri, Jul 25, 14 at 15:27

Chasing issues...

I had DE blowing back into my pool. Pulled the cover off my filter and found a cracked manifold. "Easy fix" I thought. Went to the local pool supply and got a replacement manifold. It looked a little different but the guy said it was a new, improved design. Went home, installed new manifold, put everything together and still had DE blow back. Took apart again and found some damaged grids. Decided to go ahead and replace them all. Put everything back together and still had blowback. I gave up and called local pool service. Technician came out and said I had installed all parts for FNS, not FNS Plus. Said the manifold and ALL grids needed to be replaced at a cost approaching $1K.

On top of that, on one of my fact finding missions, pool supply store guy told me to change out spider gasket. In the midst of scraping the old super glued spider gasket out, I cracked the sight glass. Pool service company says I have to replace the whole multiport valve since the sight glass is glued in. questions are:
What is the correct manifold part number for FNS Plus 60? Do I really need to replace the brand new grids too? Is there some type of epoxy that I can put on the crack in the sight glass?

I would REALLY like to keep at least some of my money.

Follow-Up Postings:

RE: Pentair FNS Plus filter

To answer your first question the actual part number for the manifold you need is 59023700. If you check out the parts diagram in the owner's manual you will see that there is only one type of manifold for this filter regardless of it's size (24, 36, 48, 60 sq ft, etc). Here's the link for the owner's manual see page 9, I will also include it on the bottom of the page:

The answer to your second question should be no. The grids you purchased are most likely universal grids. The same ones used in most types of Diatomaceous Earth filters. There should be no reason you can not use the grids you already purchased, unless the guy at the pool store sold you the completely wrong grids. That isn't likely however, as you were able to put it together.

As far as the sight glass goes, I understand where he is coming from saying the whole multiport valve needs replaced. You could attempt to remove the existing sight glass by gently tapping out the cracked pieces. Just a suggestion and not and industry approved method as you risk damaging the threads that hold the sight glass in. As far as an epoxy to use, I don't know of any off hand unfortunately.

I'll post a link below so you can see the manifold you need. It isn't an OEM Pentair manifold, but, I have used them on hundreds of filters and had zero issues. Plus the cost will probably be much more to your liking!

Hope this helps!

Here is a link that might be useful: Link for FNS Plus Owner's Manual

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