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Minisplit Minimum Capacity Range

Evazan | Posted in Mechanicals on

Hi all,

I was hoping someone could help me understand come confusion I am having reading submittals for the Mitsubishi MXZ-3C24NAHZ. The parameter I am concerned with is the minimum capacity range. When I look at the submittal for the MXZ-3C24NAHZ:\M_MXZ-3C24NAHZ_Submittal.pdf

There is a listed capacity range of 6,000-23,600 btu/h in cooling mode.

However, if I look at the submittal for the MXZ-3C24NAHZ3-U1 there is no longer a listing for capacity range. Instead, there is a parameter for Minimum Capacity which is listed as 12,600 btu/h in cooling mode.\M_SUBMITTAL_MXZ-3C24NAHZ3_en.pdf

It is my understanding that the MXZ-3C24NAHZ3-U1 is just a slightly updated revision of the MXZ-3C24NAHZ. Am I reading the submittals wrong or did the modulation ability of these get much worse? I am seeing similar patterns for all MXZ-xxxxNAHZx-xx models. The early versions reported better modulation than the newer models.

I am trying to right size my system for heating which may result in slightly oversized equipment for cooling. If the compressor could modulate down to 6k it would make me feel a lot better regarding my system size.

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  1. greenright | | #1

    A typical vapor injected non- full vrf outdoor will have a 2.5-3 to 1 turn down. Thus the 12600 btu sounds about right

  2. Expert Member
    Akos | | #2

    Take a look at the part load capacity in the chart:

    The min on these as on most multi splits is not great. Their city smart multi units seem to have better range but technical info on those is even more sparse than the MXZ units.

    1. Evazan | | #3

      Thanks for sharing that. It looks like it has the exact info I was looking for. If you don't mind, I'd just like to make sure I am reading the chart correctly. For the MXz-3C24 it looks like if the Outdoor DB temp is 86 deg f and the indoor WB temp is 67 deg f the min capacity would be 11756 btu/hr.

    2. greenright | | #4

      The Citi multi is full vrf commercial… $$$$$$$$

      1. Expert Member
        Akos | | #5

        Internet price says the SM36 or a MXZ-4C36NAHZ is about the same price. The indoor hardware is a bit more since you need a branch box ($500 to $700) with the SM. Both do almost 4 tons of heat at 5F, so that is for a pretty large new build.

        The bigger issue I think finding somebody that knows how to properly install the SM.

        If you look at cost of an SM with two ducted zones and a pair of SVZ/SUZ-KA18NAHZ, the multi zone is higher BOM cost.

      2. norm_farwell | | #6

        Mxz hyperheats with capacities above 3C30 including MXZ-4C36NAHZ were recently retired and replaced by the sm (smart multi) series.

        Mitsu says the sm outdoor units are compatible with city multi indoor units—larger air handlers, bigger ceiling cassettes etc, though that’s not reflected yet on the list of compatible units.

        Guessing installation is not much different, but haven’t gone down that road yet.

    3. bmul23 | | #7

      I just ran into the same type of issue. Is this capacity chart the standard over the submittals? It seems like if the unit can't hit the 25% threshold the submittal will state the 50% mark as the minimum.

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