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Ducted minisplit duct costs

Mike M | Posted in General Questions on

Hello all, I am planning on possibly installing three separate ducted splits in my home.for heating and cooling. The main reason for 2/3 of these being ducted is asthetics (sp?) and to help distribution.

Does it seem reasonable to pay upwards of $4000 just to install and insulate ducts and pull a vacuum on the line sets and open the valves? This seems awfully high to me as the entire home was originally installed with a 5 ton unit for 10k including the unit.

Thanks in advance.

Also as far as distribution, is it feasible a non-ducted unit could feasible heat/cool a 1000 Sq ft + room somewhat evenly?

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Replies

  1. Steve Knapp CZ 3A Georgia | | #1

    Mike. Have you had a Manual J completed on your home? You want to ensure that your system is properly sized and not based on someone's rule of thumb. See this article for more detail on why this set is so essential: https://www.greenbuildingadvisor.com/articles/dept/building-science/manual-j-load-calculations-vs-rules-thumb

  2. Expert Member
    Dana Dorsett | | #2

    Mini-splits are generally more expensive than centralized ducted systems, but not always. I've recently seen as much as 2.5 tons of ductless (3 separate units, all wall-coil types) come in around $12K., and 4 tons of multi-split (6 wall coil heads) come in at around $15K.

    Yes, a ductless head can heat/cool some 1000' spaces evenly, but it really matters what the total load is, the shape of the room, and where the gain/loss points are, and where the mini-split is placed. If most of the gain/loss is on just one windowed wall out of four, placing it above or below the window makes a difference in how evenly the space is heated & cooled. If it's an L or T shaped room with corners to get around, a single head can sometimes be a problem. You may be able to beat that by installing a higher cfm head (usually higher BTU as well), but it's not ideal.

    Mind you, $4000 can buy quite a bit of building upgrade for a 1000' room, cutting the load down to size to make the distribution issues fade, and lower the size of the mini-split.

    Floor mounted units are thinner than the high-mount wall coils, and may be able to overcome the aesthetic issues for some people. They are no uglier than hydronic heating convectors, and thinner profile than most too. Being manufactured in lower volume they're more expensive than high-mounts, but not $4000 more expensive.

  3. Mike M | | #3

    Dana/Steve,
    I've actually performed a sort of manual J minus factors such as SHG. The project overall is an addition to the main 2200 Sq ft structure which required me to remove the original compressor. My original home has floor heat that wasn't installed proprely and wilL be abandoned for now.

    The finish area will be near 3300 Sq ft. My manual J so far has been almost spot on as I calculated about 17000 btu cooling in sensible loads only and have been comfortable all summer with 15000 btu of window units (one I the master one in an office).

    The three units replace the entire original system and come out to about 3.5 tons.

  4. Stephen Sheehy | | #4

    Mike: One minisplit heats two rooms, roughly 800 square feet and 300 square feet, just fine, in zone 6 Maine. The keys are insulation and air tightness.
    As for aesthetics, the only time I think about the units is when someone walks into the house in January and says:"wow, it sure is nice and warm. What do you do for heat?"
    Our homes are filled with stuff that may be objectively ugly, but that fade into the background. Is your stove beautiful? How about the fridge? I'm no Brad Pitt, but after a while, my wife doesn't seem to notice.

  5. Mike M | | #5

    Stephen,
    Thanks for the insight. Part of the addition was adding triple pained windows, 4" of exterior insulation including taping the osb with Siga and foam seams staggered and taped as well. I know the house was terrible as far as leakage in the past as I found all of the doors and windows just set in the rough ins with no sealant etc.

    One area will be hard without ducts as it will cover 3 rooms off a shared hallway. I'm afraid a unit in the hallway would make the hall too uncomfortable. The other two units could easily be non-ducted.

    This was my reason for asking about the cost. I should also note again that the over $4000 was just for ducting. The units, linesets, etc. are all completely separate.

  6. Stephen Sheehy | | #6

    Mike- Early 2015 I paid about $3200 each, installed, for two Fujitsu RLS 3 ductless units.

  7. Expert Member
    Dana Dorsett | | #7

    Ceiling cassettes can get around the wall-wort appearance issue, but with most vendors the smallest is a 3/4 tonner. Individual room loads are nowhere near that high in tight new construction with decent windows.

    http://www.mitsubishicomfort.com/products/multi-room/product-listing/ceiling-recessed

    Fujitsu makes a somewhat lower output ceiling cassette, the AUU7RLF

    http://orders.sidharvey.com/IMAGES/specs/AUU7RLF.pdf

    Ceiling cassettes could be as much as a couple hundred more (installed price) per zone than wall-blobs , but it would take quite a few of them to add up to $4K extra.

  8. Mike M | | #8

    Thank you for the input everyone.

    I would love to use the ceiling cassettes, but 2/3 of the rooms have sloped ceilings. The last zone would require the cassette to be in a hallway, which I think could cause uneven temperatures in that area.

    I could use wall units as the wife is not all that concerned on looks, but it could create a pain running the linesets and condensate lines depending on the walls chosen.

    Would it be reasonable for the contractor to already tell me how many ducts would be off each unit without any specifications? Sounds like a "rule of thumb" to me so far. I did request calculations, but obviously won't be available until I choose heads.

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