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Community and Q&A

Fujitsu Mid Static ducted heat pumps

Tom Woodson | Posted in Mechanicals on

Anyone heard anything about the new Fujitsu Mid Static ducted units in the US?  They look awesome.  12,18,24,30,36,42 and 48k RGLXD series units rated down to -5F

The 24RGLXD for example
800 CFM, 0.8inWG indoor unit
Min/Max range of 5,400-29,000 Cooling, 5400-32,400
17.5 SEER, 12.6 EER, 3.84 COP 10.8 HSPF
Still puts out 22k BTUs at -5F

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  1. User avatar GBA Editor
    Peter Yost | | #1

    HI Tom -

    I notice no one has responded to you yet, and while I am not familiar with the system, i am using this response to "kick" it up on the home page.

    Hope the GBA community can help, as I can't - Peter

  2. monkeyman9 | | #2

    I just came across these while designing a 2 systems for my house. I was originally looking at Mitsubishi PVA ($$ and only modulates down to 10k btu) or splitting to 2 zones and using 2 Fujitsu slim ducted. These new Fujitsu's would solve my space and access issues and let me duct downstairs (instead of 2 head) so that my wife is happy and the downstairs bath is cooled on the opposite corner of the house :). Anxiously awaiting any responses on these being used.

    Can you purchase these yet?

  3. Matt F | | #3

    Do you have a link?

    Googling Fujitsu RGLXD comes with pretty much nothing.

    The Fujitsu slim ducts Slim Duct ARU7/9/12/18/24RLF top out at .36" staic and are well known here.

    1. monkeyman9 | | #4

      Here you go.

      Edit: Seeing them listed at Johnstone supply with the submittal sheets.

  4. User avatar
    John Semmelhack | | #5

    Here's a better link:

    Design/engineering manual is here:

    We haven't had a case (yet) where we needed more than an 18k unit, so we haven't used these new systems. We have used the AOU/ARU series extensively, 9k, 12k and 18k sizes.

    For zones that require more than an 18k unit, or for existing ductwork that requires more than 0.36in.w.c. static pressure, these new medium static systems should be a good option.

  5. Matt F | | #6

    John - Thanks for the link to the design manual. The first link requires contractor log in.

    It looks like the 18K unit looses some low end modulation, slim duct 3100btu/h vs med pressure 5400 btu/h.

    John, I seem to recall a someone referring to a presentation you did about designing for the slim ducts with MERV 13 filters incorporated. Is this presentation available somewhere?

    1. User avatar
  6. Matt F | | #7

    It also looks like the mid pressure series has better support for auxiliary heat, such as allowing use control based on outside temperature. This may allow for some further expanded applications.

    Now if they would only make a true cold weather compressor with a pan heater!

    1. User avatar
      John Semmelhack | | #8

      Though I'm only in CZ4, I'm not convinced a pan heater is necessary...I have colleagues with these with operation down to ~-20F with no big refreezing issues on the defrost melt.

      1. User avatar
        Dana Dorsett | | #10

        Though damage from pan ice accumulation during extended cold weather operation is relatively rare, not having a pan heater voids the warranty for that type of damage on Mitsubishi's cold climate mini-splits.

        The ice doesn't build up overnight- the fact that it can still heat at -20F and come out unscathed doesn't mean it can go for a month of operation where the temps don't rise above +15F without developing an ice plug in the drain and a build up of ice in the pan.

        If the place is occupied, and someone can monitor the situation during extended cold snaps it's not a big deal.

  7. Hugh Weisman | | #11

    here's a pdf from Fujitsu with the 18K unit specifications

    1. User avatar
      Dana Dorsett | | #12

      That's just the AHRI submittal sheet, not a complete spec. The real information is in the Technical & Design Manual (thanks to John Semmelhack, in response #5):

  8. Tom Woodson | | #13

    I'm having the 24RGLXD installed next week in a historic district gut rehab. 1650 sq feet 21k heating / 18k cooling loads in climate 4a (8f/93f design temps). I'll keep posting on how it works out.

  9. artchuck | | #14

    I’m currently installing one right now. A 3 ton mid static system . Doing this in a retrofit application. There are some quirks and little things to be aware off, but so far it’s going well.

    - must hang
    - the three ton is very long from front to back (55”) and skinny between the supply and return sides. Building the plenums is definitely been an adventure.
    - have to use new line set ..( think minis split, both lines insulated .)
    - air handler powered by outdoor unit( think mini split)

    Should be finishing up Tommorow , I’ll post some pics when finished.

    1. Tom Woodson | | #15

      My install is wrapping up as well. I definitely choose the wrong contractor. Good reviews and recommendations didn't save me. I've had to get after them about every detail on the duct work, indoor unit and outdoor unit. Very frustrating. Just hoping i can get the end product to acceptable at this point.

      Funny to hear you had an adventure building the plenums, my contractor had to remake them 3 times before they got it right.

      I'll try to post pictures as well.

  10. User avatar
    John Heckendorn | | #16

    @artchuk, @Tom Woodson:

    How did the install go? Any pictures? The biggest challenges you encountered?

    And how has the Fujitsu been operating for you? Surprises good or bad?


  11. MattFreedman | | #17

    I'm considering the Fujitsu medium static mini split system to replace an existing gas furnace in my 1930s home in the Berkeley hills (east of San Francisco). I need it primarily for heating but would like the cooling option for future summer heat waves. My house has about 1900 square feet on 3 levels, single pane windows (vintage steel casement) and very little insulation (spanish revival plaster/lathe/stucco). All the flexible ducting has just been replaced but the original rigid ducting inside the walls is unchanged (would require tearing apart all the interior walls, not going to happen).

    After measuring the space and doing the load calcs, my installer is recommending the 42RGLX (42,000 BTU) to replace my current gas furnace (that puts out 99,000 BTUs). This is one of the largest options in the Fujitsu lineup. The price quote is around $16k. The install is somewhat more complicated than a typical setup due to weird routing of the line sets and challenges getting the 220v power to the main panel.

    Two questions for this group:

    (1) Does this sound excessive (in terms of sizing or price)?
    (2) Are folks having good experiences with this technology in an older home like mine that is not well insulated and has old windows? Another installer warned me away from using mini split technology, saying that most people who've chosen this route end up regretting it.

    Any thoughts or insights would be greatly appreciated.

    1. User avatar
      John Heckendorn | | #19

      @MattFreedman, just curious as to whether one of your drivers is a level of PV generation capacity that will make the minisplit -- already pretty efficient -- essentially "free" to operate.

      1. MattFreedman | | #20

        John - I don't have a PV system right now. May get one in the coming years. The driver for me is the ability to switch to high efficiency electric and to incorporate cooling. My wife is very sensitive to heat and the current trends suggest that we're in for actual heat waves in the East Bay in the coming years. We are doing work on the furnace/ducting right now, it is seems like the time to consider the switch.

        Also, my use of the mini split will skew heavily towards nighttime in the winter and fall. That means any PV system wouldn't directly be used to power the units. I would have to rely on time-based export credits for the PV, which are going to decline significantly in the coming years due to changes in mid-day market prices resulting from high penetrations of solar on the system. The correlations are much better if it's being used for cooling during the summer.

    2. User avatar
      Dana Dorsett | | #22

      A 3.5 ton heat pump for a 1900' house in Berkeley is ridiculous. This 1200' house in Berkeley is heated/cooled with a 1.5 ton Fujitsu, (and it's somewhat oversized for the loads):

      Get a second opinion (or quote) from Larry Waters, the guy who designed that system:

      Before blowing the budget on oversized mechanicals, start with a serious assessment of what can be done with the building envelope first. Six grand spent on retrofitting the building envelope and spending ten on the mechanicals is greener and more comfortable than just throwing an oversized mini-split at it.

      Retrofitting low-E storm windows over the steel casements is probably do-able without destroying the vintage aesthetic, and depending on the wall stackup you may be able to dramatically improve the wall performance at low cost, low risk too. At the VERY least some blower door & IR imaging directed air sealing is going to be be "worth it".

      1. MattFreedman | | #23

        Dana - thanks so much for the response.

        The challenge is that my house is a historic spanish revival that is very difficult to retrofit without seriously changing the look and feel of the entire house. Adding interior storm windows is very difficult because most of the widow openings are curved plaster (over lathe) have no flat space for any additional layers. I think these openings might need to be rebuilt to accommodate another window. I could swap out the glass in these 1930s windows but there are many small panes (some windows have up to 8) so the labor could prove cost prohibitive.

        My quote for the Fujitsu system came from A-1. They sent someone to measure every room and survey the condition of the home. They told me that a smaller system simply won't work for me. I was surprised at the sizing but it appears to be a result of my home having lots of old leaky windows and very little insulation. It might also be A-1 trying to cover themselves against a future complaint that the system isn't powerful enough.

        I would be happy to spent some money on improving the building envelop to improve efficiency. Just not sure how to make that happen without ripping open all the walls/ceilings (which have vintage hand-textured plaster), redoing the lathe, and essentially renovating the entire home.

        What kind of improvements could be expected from IR imaging and air sealing?

        Much appreciated.

  12. Tom Woodson | | #18

    Seems a little high on the sizing consuming though the moderate climate. Have you tried to do a back of the envelop calc or even try doing a room by room using coolcalc ? It might be worth it to spend some of those dollars on a blower door test and air sealing efforts in your attic/basement/crawlspace.

    As for pricing, I’m not surprised given your market and the newness of the equipment. Just make sure they follow the manual.

    As for how they work, I can’t comment yet as I haven’t started mine up... waiting for the electricians to finish. I have very high hopes for comfort level given the modulation capability. Efficiency is a given. I think these types of units are the future. The US has housing stock is loaded with central air hvac systems. The possibly of larger ducted inverter driven heat pump units is realistic, and given electricity availability and production via solar, I think we could make a huge dent in our reliance on gas/oil for heat.

    1. MattFreedman | | #21

      Tom - Thanks for the feedback. Please report back when your unit is operating.

  13. User avatar
    Mark Walker | | #24

    The RGLXD series isn't listed on the NEEP Cold Climate spec spreadsheet.
    Does anyone have the min/nominal/max capacities and COPs at 47/17/5F for the various sized RGLXDs?

  14. User avatar
    Jon R | | #25

    > I have very high hopes for comfort level given the modulation capability.

    That compressor modulation capability is more likely to cause discomfort at low loads. The fan modulation range is only 400-800 CFM, so expect no dehumidification at 5400 btu/hr.

  15. Tom Woodson | | #26

    John R. Are you saying there will be too much airflow to dehumidify at minimum load?

    Here is the design/tech manual if you want to look up capacity and cop.

  16. Nick DeFabrizio | | #27

    Hoping to rev up this thrad-I am looking at the mid static 12,000 units. New Jersey gives a $2,000 rebate per ducted unit, only $1,000 for a similar sngle non ducted unt so clearly there is an incentive to use these units. They seem perfect for coverng a few bedrooms at a time....Hav ethey performed well?

  17. Matt F | | #28

    I haven't heard of anyone actually putting one in.

    The 12,000 btu unit looks good and surprisingly is reporting a slightly higher HSPF of 11.7 vs 11.5 for the standard pressure unit. To do that, I think they upped the cfm from 383 cfm on the standard to 500 cfm on the mid static.

    That increase in nominal CFM works out to roughly a 100% increase in static pressure on the same duct system (500^2/383^2=1.7). You have 120% more static pressure available, so there is still a window ahead when running tighter ducts, it's just not as big of an advantage as it first appears. I haven't dug too much further into nuances of the fan curves between units.

    This 12K looks like a decent choice for cold climates, I haven't checked what the price premium is.

    The 18K has the apparent disadvantage of loosing low end modulation, 3100btu to 5400btu.

    *I was thinking about this more, and realized I used the wrong CFM for the low static unit and corrected it. So if you had a duct system at .36" static with the standard unit and swapped in you would be at .61" static. So you have .19" additional static at 500CFM, which is like .11" static at 383 CFM.

  18. Robert Navarro | | #29

    Posting so I get notified of replies to this.

    Also interested in these units.

  19. Jonathan Lawrence CZ 4A New Jersey | | #30

    I have the 12k unit at my jobsite now scheduled to be installed the first week of October. As soon as I have some data to report I will post it.

    1. Nick Defabrizio | | #31

      Thanks. I am in Sussex County NJ so would be curious as to how yuor install comes out. These are avalable at Ferguson and many other wholesale shops. They seem ideal and meet New Jersey's criteria for the larger $2,000 per unit) rebate...

  20. Jamie B | | #32

    Does anyone have the pricing info handy?

    I think last time I talked to my supplier, the cost of the 12k slim duct and the 12k mid static are roughly the same. But I can't remember the rough difference.

    It seems the mid static is the better performer, and when doing a new build i might as well put it in.

    Thinking of a future build and it looks like the mid static is the better performer. In my case, I would mount it above the ceiling, so I have to preconsider the joist cavities for mid statics. It would mean increasing the joist height, or taller walls and furring the joists down to accommodate them.

  21. Matt F | | #33
  22. Jamie B | | #34

    Thanks Matt,

    If you filter for 1 ton. It'll shower the slim duct and mid static side by side. Looks like $381 difference per system.

    The next question is costing a multiunit system. They have a bunch of slim duct bundle packages, I can't find the mid static on there.

    So let's say 3 indoor units with one outdoor. Although less energy efficient, the total cost efficiency might outweigh the actually energy saved from an ROI standpoint.

    Any thoughts?

  23. Tom Woodson | | #35

    Just a quick update on the Fujitsu as I work though this slow gut rehab construction project. I had the 2 ton installed earlier this year. I have been very impressed with how quiet this unit is. I have 1700 sq feet with 9 rigid duct runs off of a main trunk. You almost can’t hear even at full throttle and it is moving a lot of air. Same goes with the outdoor unit.

    I thought I did a good job on the calcs, so I was also please with the conditioning results so far.
    -Pre spray foam it was able to cool the building to 70 on 93 degree days.
    -I put it on heat mode tonight to dry paint and it brought it up to 72 in no time. I’m expecting it to freeze overnight here so fingers crossed it keeps running.

  24. Jamie B | | #36

    Hi Tom,

    Awesome! Thanks for the update.

    Just curious, What are your duct sizes? And how much cfm have you calculated?



  25. Jonathan Lawrence CZ 4A New Jersey | | #37

    I will 2nd what Tom said above. The mid-static unit is very quiet. The unit is suspended from the rafters and all of the duct is hard pipe with R8 insulation wrapped around and I have a hard time telling the unit is on. Looks like we are finally going to get some cold temps so I hope to have some more data to report in the near future.

    Btw - just to give an idea of how new to the market these units are - the serial number on mine is 0000016.

  26. jeffesonm | | #38

    Anybody else have any feedback on these? I don't see much out there, presumably because they're so new.

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