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Installing a Ceiling-Mounted Cassette

mdhomeowner | Posted in Mechanicals on

I am looking at putting Mitsubitshi mini splits in the second story of my house. It was built as a few additions, so the ducting and HVAC isn’t quite up to par.

The square ceiling mount cassettes look like they should fit right in, but all of the literature for them points to them fitting in ceiling tiles. My trusses are 24 inch OC, which leaves right about 22.5 inches. The manual states that the width is 22-7/16, but that the opening should be 22-11/16.

Has anybody successfully installed a square ceiling cassette in a framed ceiling?

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Replies

  1. Patrick_OSullivan | | #1

    It's been a while since I researched this to any degree, but here are some thoughts. Because these square units are often meant for drop ceilings rather than drywalled ceilings, a couple things may come into play:

    1. Attachment. Things that are meant to be installed in joist bays typically have mounting points to facilitate it. Cassette type units are likely designed to be hung from threaded rod or cable, so that may influence how they would work in this situation.
    2. Serviceability. You may need to install an access panel adjacent to the unit as some things are meant to be serviced from the surrounding area. Not a problem in a drop ceiling, but tricky in a drywalled ceiling.

    Mitsubishi also makes a ceiling cassette meant to be installed in a drywalled ceiling. (MLZ product line, example: https://www.ecomfort.com/Mitsubishi-MLZ-KP09NAG/p82597.html). They're designed for 16" OC but could of course be installed in 24" OC with some blocking.

    > I am looking at putting Mitsubitshi mini splits in the second story of my house. It was built as a few additions, so the ducting and HVAC isn’t quite up to par.

    If the 2nd story of your house is where bedrooms are, ductless units may not be ideal as they each will likely be oversized for a single room.

    1. mdhomeowner | | #2

      Thanks for the info. The main reason I like the 24 " cassettes over the 16" cassettes is that they seem to spread out the air a lot more since they have 4 vanes.

      I have 200, 250 and 600 sq ft bedrooms to heat and cool. 6/6/12 BTK is optimal, but it seems like the smallest cassettes are 9k.

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