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Community and Q&A

single zone minisplit SEER vs. SHR

Charles Campbell | Posted in Mechanicals on

Is it true that single zone minisplit SEER is directly correlated to SHR? I’ve seen a 33-SEER unit with a SHR of 0.96. Does this mean that high-SEER minisplits should only be installed in desert climates? How high can you go with SEER in the Atlanta climate without causing humidity problems?

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  1. Jon R | | #1

    Correlated but not directly. But also note that you can't make much use of a single SHR rating anyway - SHR varies significantly with load and most operation is at partial load (where manufacturers often produce a near 1.0 SHR and almost no dehumidification). Dry mode may or may not work well (too cold is a common result).

    I would give some preference to a Daikin Quaternity. Or plan on a) significant use of a dehumidifier and/or b) periods of more than optimal interior humidity.

    1. Charles Campbell | | #2

      Jon R, thanks for your reply. How does Daikin Quaternity achieve low SHR? What is its SHR? Looks like the answer to my question about desert climates is mostly "yes". Otherwise in the Atlanta climate, adding a dehumidifier means you have lost the energy savings of high SEER.

      1. Jon R | | #3

        It has another coil providing the ability to re-heat air after extracting moisture. Plus it seems to have reasonable CFM/ton values at low loads. It also costs much more.

        1. Charles Campbell | | #4

          The spec sheet on the smallest Quaternity is really confusing. On the one hand, its SHR appears to be 99%. On the other, it removes 3.3 pints of water per hour. How is this possible?

          1. Jon R | | #5

            Just measure SHR at a different fan speed or compressor output. Or with the Quaternity, a different amount of re-heat.

            Maybe there are extended specs available that provide usable latent specs (for any mini-split). If not, you can guess at poor performance based on compressor vs fan range. For example, a 300/400/500 CFM fan and a 1 ton compressor with a 4:1 turn-down ratio.

            Note that these issues are far more important to comfort and efficiency than moderate amounts of inverter mini-split over-sizing.

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