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Community and Q&A

Inline Filter Kit for Fujitsu Slim Ducted

mgensler | Posted in Green Products and Materials on


We’re in the design stages of our ductwork for conversion to mini-split HP. We’ve spec’d Fujitsu equipment and are planning on the slim ducted versions. For one unit we are looking for a filter kit similar to the Mitsubishi FBL series. The Mitsu is a little too large for our unit. Does anyone have any options they’d recommend that will for with Fujitsu?

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  1. Expert Member
    Akos | | #1

    Any sheet metal shop can fab your a similar filter box to your exact size.

    If you want to use off the shelf parts, easiest is to get a reducer made to use one of the Mitsubishi parts or use one size larger filter box and block off the extra length with sheet metal.

    I personally like to use very short return ducts and a filter grill. These can now take standard size furnace filters that are stock item at the box stores (16x25 or 20x25). Much easier than having to special order oddball sizes.

  2. mgensler | | #2

    Thanks! We're using the filter grille you recommend for two other mini-splits. This unit has returns in four rooms. We were trying to keep things simpler. If we did go with filter grilles at each return that would cut don on the dust in the ducts. Do they make a standard size one that fits in one stud bay? I think the rectangular return duct we will be using is 14".

  3. Expert Member
    Akos | | #3

    My local hvac supply place can order filter grills in any size in 1" increments. 14" wide is very common.

    Having to replace 4 filters in each room is a bit too much. A single central filter is the best way to go in that case. Even with a central filter, having a washable pre-filter for each grill will go a long way in keeping the ducts clean.

    You should be able to mate one of the Mitsubishi filter boxes to your unit without too much fussing.

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