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Ducted/concealed mini-split without supply or return plenums – straight out the wall?

neockder | Posted in Mechanicals on

I’m planning to install a “ducted”/concealed Daikin LV unit on the second story of my house. I haven’t been able to find any definitive answers on plenum requirements, or lack there of.

the plan includes hanging the unit from unistrut in the hallway, observing all of the required tolerances for access and space around the unit. A sofit will then be built around the unit.

My question is in regards to the minimum allowable ductwork, or if there is any. The unit will be situated such that it faces the bedroom, and the supply will go directly through the wall (header and boxed for unobstructed flow). In other words, can the supply plenum simply be a 4″ length between the unit and the trim/grille, or does the unit have to be set back from the grille a ways for some reason?

Same question goes for the return plenum. Can that ductwork be minimal between the return vent and the unit? From my perspective, I don’t see why not – as surface mount mini-splits have no ductwork at all.

Thank you for your help!

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Neo,
    First of all, can you tell us your name?

    Q. "Can the supply plenum simply be a 4-inch length between the unit and the trim/grille?"

    A. As far as I know, the answer is yes.

    Q. "Same question goes for the return plenum. Can that ductwork be minimal between the return vent and the unit?"

    A. As far as I know, the answer is yes. But if you have any further questions on this issue, there is no reason you can't call Daikin and ask to speak to a technical representative.

  2. neockder | | #2

    Thanks Martin. Definitely something I'll do before getting too far into the process!

    Cheers,
    Nick

  3. user-953897 | | #3

    My experience with ducted minisplits (mostly Mitsubishi) is that very short ductwork makes the unit's noise much more noticeable. Also, a filter is needed in the return ductwork prior to the unit.

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