GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Mitsubishi minisplits — horizontally ducted

user-6056070 | Posted in Mechanicals on

Sorry – I blv I posted the same in another section. Please ignore this question if it’s a duplicate.

We are not fans of ductless units. Therefore, we opted for the hidden horizontally ducted units that Mitsubishi provides. Unfortunately, all the Mitsubishi contractors we talked to have never designed a home with these type of units. Plenty of ductless experience.

We have detailed CAD and Architectural drawings of the home. Does anyone know of a design firm or professional that is willing to design the placement of these units, piping, etc.? We would like someone to advise us on where we should place units, if we need small bulkheads and in some cases we may just have to place a wall mount unit. In addition, we want the designs done so we hand them to a contractor that can install these units.

I would appreciate any help.

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. user-6056070 | | #2

    I actually contacted both - none of them responded. I gave up after multiple attempts.

  2. Expert Member
    Dana Dorsett | | #3

    Finding a competent ducted mini-split installer is a bit like finding a needle in a haystack, but they are out there. I've had marginally better luck with Fujitsu mini-duct installers than Mitsubishi, but even then getting them to do it the way you like it can be a bit of a struggle.

    If you don't like wall-units, how do you feel about ceiling cassettes? Mitsubishi SLZ-KA series come as small as 3/4 ton:

    Alternatively, the MFZ-KJ and MFZ-KA floor units are pretty good, and more efficient than the ceiling cassettes:

  3. bradrh | | #4

    What is so complicated about installing a ducted minisplit? What is so different from a traditional ducted heatpump system? I ask because I'm heading down that road myself. Heat pumps are pretty uncommon here (CO), and minisplits even more so.

  4. Expert Member
    Dana Dorsett | | #5

    The complication a single phrase:

    Duct design

    Many mini-split installers would rather not deal with that detail, and man not have the skills & tools for doing a Manual-D. Most split system HVAC installers look at the blower specs for a mini-duct cassette and roll their eyes or flat out tell you that it can't be done, mostly because it's outside of the range that they have a good feel for, and thus can't design it mostly by the seat of their pants or on the back of a napkin they way they can with heavier duty air handlers.

  5. user-6056070 | | #6

    Dana - do you design these systems? I would love to hire you. Also, due the unique design of our home, we cannot use cassette units. It won't fit. The only option is horizontally ducted units. These units need space for maintenance and typically we would have to drop them with bulkheads or strategically place them in closets etc.

  6. Expert Member
    Dana Dorsett | | #7

    Ismail: Though I'm not immune to hacking on my own ducts I'm not in that business, and would hire somebody with the design tools & experience to get it right the first time, if you can find a pro up to the task.

  7. JC72 | | #8

    Call them? I've had success via phone.

  8. user-1137156 | | #9

    The Mitsubchi ducted indoor unit has a MUCH lower allowed static pressure, 0.2"WC, (duct friction allowance) than the Fujitsu units @ 0.38"WC. Perhaps that is why Dana has found more support for the Fujitsu. Also the energy used to power the fan(s) is significantly lower with the Fujitsu product. Yet another benefit of the Fujitsu units is that they can be mounted for vertical flow, giving the option of placing them in a wall. Please share a few more details about your house, # of floors, foundation type, insulation and air sealing level? Do you have heat loss/gain estimates (manual J)?

  9. user-6056070 | | #10

    The home is gut rehab, 3k sqft, 2 floors with basement. Yes we have the manual J and S.

  10. user-5946022 | | #11

    Jerry - please clarify what you mean by mounting the Fujitsu for vertical flow in a wall? Would this be like mounting in a crawl and running the duct up into the wall for baseboard registers?

  11. user-1137156 | | #12

    These ducted split "heads" need to be somewhat accessible for maintenance like filter cleaning, unlike a basement, a crawl space mounting seriously limits such access. Mounting the unit vertically, between two stud walls that combined are the side wall of a closet allows, for example, easy access through a remove-able panel in the closet, while return air ducts are in the floor (assuming open web floor trusses) terminating in low mounted return air grills along interior walls while output ducts ( in an open web truss ceiling) lead to ceiling mounted "registers" near exterior walls.

  12. user-5946022 | | #13

    Jerry- Sounds interesting - is there a link that shows this type of installation?
    In a very tight house, would it matter if the supply registers are near exterior walls? I thought one advantage of a tight house is the supplies could all be near the center of the house, requiring less duct and making the system more efficient?

  13. user-626934 | | #14

    Fujitsu slim-duct air handler in upflow position attached...

    CL - it's fine to put the supply registers near the center of the house, as long as you're getting good mixing within the room. In the case attached, the ductwork runs in a raised soffit truss above the second floor ceiling, but below the attic air barrier and insulation. Supply registers are just over the doorway to each room and supply the air parallel to the ceiling by using a single-throw register with curved scoops.

  14. user-6056070 | | #15

    Hello all. I wanted to post a final reply so other consumers may benefit. I did reach out to, energyvanguard and lssquared. LSsquared was charging upwards of 4k just which made no sense to us. Energyvanguard was responsive at first and within budget but once the deposit was paid they disappeared. It was a disastrous experience and I had to open a dispute with Paypal after which I received my deposit promptly. Maybe they were super busy but strange business ethics.

    Finally, came to the rescue. In $600 I got the design done, Manual J and S and support that was above and beyond. Isaac went over the top to ensure we got our permits approved. Last minute we even changed the equipment with minimal documentation and Isaac was able to research and re-send us the Manual-S.

    I just wanted you all to know that if you need Manual J, Manual S, design of your HVAC system for inverter based system or a traditional system, then please head to

    I hope this post will save you folks some of the pain we had to go through in order to get our permits approved by the city.

  15. user-2310254 | | #16

    Ismail. That is good to know since I am starting to create a contractors list for my next project. Are they local to the Atlanta metro area like Energy Vanguard and LSsquared?

  16. user-6056070 | | #17

    I am not sure where Isaac is based but he had all the wet/dry bulb information for Chicago. Everything was done remotely so we had no issues.

  17. GBA Editor
    Martin Holladay | | #18

    Isaac Savage, the owner of Home Energy Partners / HVAC Design Pros, is located in Asheville, North Carolina.

  18. GBA Editor
    Allison A. Bailes III, PhD | | #19

    Ismail, I apologize for the trouble you had with our service. I've spoken with our team about what happened and found out that it was indeed a busy period. That's no excuse for letting the communication lapse the way it did. I first found out there was a problem when I got an email from PayPal saying that your claim had been escalated to a dispute, and we refunded your money right afterward.

    It should never have gotten as far as it did, though, and again, I apologize for our lack of communication and for not getting the work done within your time frame. We're revamping how we handle our workflow to prevent this kind of problem from happening again. I'm glad you found Home Energy Partners. Isaac is one of the best in the field, so I'm not surprised to hear that you got such great service from him.

    ~ Allison

  19. whitenack | | #20

    Ismail, Just curious, how long was the turnaround to get your manual J?

    Regarding the pictures that John posted, on the top pic, I assume I am looking at the wide part of the unit? And the bottom box is the return plenum? Is the return air grill on the other side of the unit from the camera or does it open out to the right of the unit (or neither, the return air is ducted back to the unit under the floor)?

  20. user-626934 | | #21

    Clay - yes, you're looking at the wide side of the air handler. The box on the bottom is the return plenum. Return air filter grille is to the right....not an ideal return duct scenario from a noise transmission standpoint....but we had very limited space for the install.

  21. user-6056070 | | #22

    Both the Manual J, S and design layout with ducts and unit placement took about a week. We were looking at Mitsubishi units but are now considering Gree units. If you folks want to review the models of Gree, let me know and I can post their manual and details here with product options. Very similar to Mitsubishi but much cheaper. I will ask the Gree dealer to check this forum, in case you folks have questions.

  22. kenorakq | | #23

    Ismail, thanks for the reference the Gree (a Canadian Company...who knew)

    ...I just checked the website and the U Crown series 9000 btu units look very very promising. The advertised 100% heating performance (9000 btu) at -30c beats Fujitsu and Mitsubishi ... IF ITS REAL.

    Are you in Quebec? I see the company is just outside Montreal and I hope their claims are real.

    Have you seen these units in operation? I'm not trying to pee on the parade but it sounds too good to be true.. Better performance for less $$$...

    Don't take my comments wrong... I WANT THIS TO BE TRUE.... I need to read some customer reviews etc...

    Please take a few more minutes to tell us more about Gree.

    Cheers from Kenora Ontaio

  23. kenorakq | | #24

    btw...I emailed the company looking for a dealer..

  24. user-2310254 | | #25

    Tim. Gree is based in Zhuhai, China ( That doesn't mean its products are no good, but you will want to check out the product, installation, and service reviews.

  25. kenorakq | | #26

    Steve...thanks for the update; I was a bit excited by the performance numbers (claimed) so I started doing some research and found the same thing... made in China. Not that is necessarily a bad thing cause most of the things I have in my home are likely made there now .

    I can't find any reviews or real world reports on the U Crown series (heat to -30c)... I'm hoping my email to the company will answer some questions...

    The OP has been in contact with the company...I'm hoping either he will come back with some more info or the company rep will post here..

  26. user-6056070 | | #27

    Guys - Gree is a Chinese company. I have not experienced them before and will be installing them in my home (Illinois) for the first time. I will definitely update with pictures and experience etc. The dealer in the US is Kevin from YMGI. I will ask him to reply to this forum. Also, the dealer in EMEA and other regions is Nia Limited.

  27. user-6056070 | | #28

    Ok - I uploaded the manual for the units we will be installing. We are using two 4 ton exterior units GMV-48WL/B-T(U), six interior GMV-ND07PLS/ A-T(U), one interior GMV-ND12PLS/
    A-T(U), and two wall mounts GMV-N09G/A3A-D(U)

    For the manual and design specs: please use this link.!AoshNMIK0hCuhO1vy0RsY4xhMbDQrA

  28. Isaac_Savage | | #29

    Ismail asked me to chime in here so I can respond to any direct questions about his project or my services. We actually ended up with two 3-ton outdoor units on his project. I hadn't seen Gree before this project, and have generally leaned toward Fujitsu for ducted systems in the past due to their blowers having more available static to work with.

  29. | | #30

    Hi, Everyone,

    Gree VRF heat pump system with hyper heat 80% capacity down -22F is used in Ismail home project in Chicago. This is a mini version VRF that can be replacing traditional central system Furnace + A coil, which is much less efficient, much noisier and less health than mini split VRF system.

    YMGI offers VRF systems:
    Outdoor units-modular 3,4,6,8,10-Tons.
    Indoor units-wall mount, ceiling mount, ceiling/floor mount, recessed fan coil low profile (7.8" think) low static, medium and high static 09K-96K But/h.

    YMGI Group HVAC and Solar Supply
    601 Arrow Lane
    O'Fallon, MO 63366
    Tel.: (866)833-3138
    Fax.: (866)377-3355
    Email: [email protected]
    Web site:

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |