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Ductless minisplit vs ducted split AC systems for whole-house application

GBA Editor | Posted in Mechanicals on

I’ve read about a builder in NC that uses ductless minisplits in a whole-house new construction application. What are your thoughts and commentary about such an application?

To run refrigerant tubing vs. a potentially leaky duct even in the conditioned space would seem to be preferable. Not to mention the zoning advantages and conditioning occupied space vs conditioning unoccupied rooms in a non zoned split a/c or h/p system.

Would the house design have to be less flexible? For example I think most minisplits’ minimum is 9,000 BTU. That seems more BTUs than needed for most bedrooms. Also I would think that the design could not have a hallway. Traditional split a/c systems with duct work still seems primitive.

I live in southeast Alabama, a hot and humid climate.

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Replies

  1. User avatar GBA Editor
    Martin Holladay | | #1

    Norman,
    1. Ductless minisplit systems cost more than conventional whole-house AC systems.

    2. A single ductless minisplit outdoor unit can serve several indoor units, so a 9,000 BTU unit could serve more than one bedroom.

    3. Why would either AC choice preclude a hallway?

  2. John Brooks | | #2

    Martin,
    I know from experience that the "ducted" minisplit sytems are very Pricey.
    I am surprised to hear that "ductless" minisplit systems would cost more than conventional whole-house AC systems.
    No doubt that the minisplit equipment is pricey ...but it sure seems like there would be a big savings on site labor and ductwork with a Ductless system?

  3. Rick DuRapau | | #3

    I'm not a professional who's been in the biz for 100 years. I'm doing a major remod with my son on his new 30 year old house (2000 sq ft). In my mind, there is no other way to do HVAC than "ductless". I think it's absolutely brilliant. Total control, super efficiency, with no ducts - how could you choose anything else.

    Some extraneous thoughts:

    The term "mini split" should be dropped - there are some huge systems out there. Just call 'em "ductless".

    You're going to have to do a lot of research for yourself. Four AC professionals that I've talked to have all balked. "...uh...are you sure you want to do the whole house? ..whistle...that's...hmm, I'm gonna have to ask Carl... Then, never get a call back.

    There are ways to handle small spaces with sharing a "blower". Also, 6K units are common.

    To me, ductless is more flexible, not less. You don't have to design around ducts.

    We have fought & clawed to take advantage of every square inch of this house, why in the heck would we give it up to ductwork?

    I'm not dismayed by the costs. We're going to do the install ourselves. And, we are going to do a Manual J.

    Of course, I could be wrong - stay tuned.

  4. User avatar
    Dana Dorsett | | #4

    You realize you responded to a 3-year old thread, right?

    Ductless technologies still have to be sized correctly for the loads, and the "head in every room" approach is both expensive and inefficient due to oversizing issues. But yes, the potential efficiency gains over ducted systems are large when done right.

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