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Community and Q&A

Choosing and Sizing Minisplits

indoorsy | Posted in Mechanicals on

I live in a coastal town north of Boston. My 1200 square foot house (600 upstairs, and 600 downstairs) is heated via electric baseboard heating. I never go above 60 degrees in the winter and still spend over $400 per month and this is with each room with its own thermostat and me turning them all down to mid-50’s when no one is around and only turning up those rooms where we are. It is ridiculously cold in my house in the winter.

I had Mass. Save come in to see if there was anything else I could do and their suggestions was to add hyper heat mini splits to the house. They sent a contractor who gave me a quote for one unit to heat/cool the entire first floor, a 24K BTU unit and then two for each of the kids rooms upstairs, each 6K. He said I’d need a new sub panel and included that in the quote. Outdoor condensor would be, MXZ-3C30NAHZ2. The contractor was not from my area and I was skeptical that one until located in the living room on the first floor could reach the other rooms (bedroom, kitchen, bathroom). For such a big purchase I opted to get another contractor in.

The second contractor went with a 9K unit in each of the three bedrooms and an 18k unit in the living room (so four indoor zones vs. three from the previous contractor… he said 24k was way too much for the living room and that I would not feel any of the effect in my bedroom, kitchen and bathroom as the air simply would not travel that far). The outdoor condensor would be: MXZ-4CNAHZ-2

The second contractor would eliminate the three baseboard heaters in the living room and use their spot on the electrical panel such that I would not need a new sub panel. The elimination concerns me a bit but they produce nothing of comfort for us so I guess not a big loss.

I wanted to get one additional contractor in as I have heard such different approaches from the two contractors. The first two contractors are qualified through Mass. CEC to offer good rebates for Mitsubishi. The third can offer Mass. CEC rebates only for Fujitsu. All three can offer Mass. Save rebates but those are small compared to the Mass. CEC rebates.

So now, I am so thoroughly confused and thus reaching out for help.

In reading through other threads, Fujitsu seems to offer better efficiency and that is a BIG goal for me. I want to be comfortable this winter without going broke. But if reliability is an issue, then what is the efficiency worth??

Background on the house. There is spray foam insulation under the subfloor in the living room (which I added when I moved in as the floors were ice cold and they were replaced so allowed me to do this). But the walls seem to have very little insulation. They are cold to the touch and despite the work I did on the floors, we are freezing and it always feels damp and cold. There is no basement. I added spray insulation in the attic between the rafters. I also did this to any walls that were opened up while I was renovating but most walls were not touched.

Thank you and sorry so long. I am in over my head evaluating all of this on my own.

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  1. GBA Editor
    Martin Holladay | | #1

    It's going to be hard for us to give you advice over the internet.

    Here is some basic advice:

    1. If your walls are uninuslated and your house is cold, the house could benefit from weatherization work (performing air sealing measures and adding cellulose to the uninsulated walls). A home performance contractor or a weatherization contractor who can perform a blower door test should be able to assist you with advice on how to proceed.

    2. If you don't trust your HVAC contractors to perform you heat loss calculations and heating system design -- and there are good reasons why you might not have that trust -- you might want to hire a third party to perform the load calculation and heating system design. More information here: Who Can Perform My Load Calculations?

  2. Expert Member
    Dana Dorsett | | #2

    Your DOE climate zone is 5A, not 6B. (Massachusetts, not Montana.)

    A 9K ductless head is oversized for almost ANY bedroom, unless you sleep with the windows open when it's +5F outside. (An exception might be a completely uninsulated house built out of 6" thick quarried granite blocks or similar.) Even framed wood-sided houses with no wall insulation won't have bedroom heat loads close to the ~10,000 BTU/hr that a 3/4 ton cold climate ductless can deliver a @ 0F. The "head for every room" approach usually results in suboptimal or even ridiculous oversizing factors.

    You can probably do a LOT (and get the best bang per buck) with just one or two ductless heads- one per floor, but it's useful to know the whole-house heat load first to get the sizing right.

    Since you have a heating history on the place, run a fuel use load calculation using 55F as your heating base, then project the linear approximation to a balance point of 65F (or an indoor temp of 68F.) See:

    If that's going to be too painful, if you're willing to share a couple of last winters' electric usage (in kilowatt-hours, not dollars), your ZIP code (for weather data purposes) and the EXACT meter reading dates, I can run the numbers for you here on the forum.

    It's not too hard to figure out if the walls are insulated, and MassSave will subsidize retrofit wall insulation. With some true colonials that have clapboards nailed directly to the studs retrofit insulation often becomes too risky (unless you're willing to re-side the house at the same time), but most houses can be safely retrofitted with wall insulation.

    The notion that Fujitsus are somehow always more efficient than Mitsubishis isn't particularly well founded. A lot depends on the sizing of the unit relative to the load. While the HSPF numbers for one unit might be higher than another, if it's over or undersized for the load it may not come even close to meeting those numbers. A wide modulation range can count for a lot, and when going for a single head for every room the lower minimum modulated out of the Mitsubishi FH06 or FH09 compared to that of a Fujitsu 7RLF or 9RLF can more than make up for any marginal efficiency difference at the (much higher) modulation levels at which they were tested. But if you end up going with one head per FLOOR solution the differences are smaller. If it looks like a 1.25 tonner is what's called for the Fujitsu 15RLS3H has a lower minimum modulation than the Mitsubishi FH15NA, and would probably edge it out in overall seasonal efficiency. If it's the 1-tonner they're pretty equivalent.

    Not all 18K or 24K ductless heads are equivalent or even different model numbers for 6K heads. To be able compare the proposals it's important to list the exact model numbers of the heads, as well as the compressors.

    Getting a third party room-by-room Manual-J load calculation from a P.E. or RESNET rater (not an HVAC contractor) based on the "after" picture of any building upgrades will usually save more than the cost of their fees in lower up-front equipment costs, and provides a means of sanity-checking proposals.

  3. indoorsy | | #3

    Thank you both~ Very much appreciate the time you've taken. I've had Mass. Save here twice and each time asked about adding insulation and was advised both times that I am not a good candidate and have done as much as I can do in that regard (attic, etc).

    On this last visit, I was told that they could bring someone in to evaluate what is going on with insulation inside the walls but that is hard to do when the inside temperature is the same of the outside and would need to be done once the weather turns cold.

    I get a little PTSD about winter coming because of the frigid conditions combined with huge electric bills and hoped to get the mini splits installed this fall such that we will have our first comfortable winter here since moving in nearly four years ago. BUT, if getting this done without ALL the information seems foolish, perhaps waiting makes sense??

    Dana, my goodness, thank you for offering to help me figure out the fuel use load calculation. Here is the info...
    zip code: 01944
    On the bill, it states "next meeting reading on or about"... so I am providing that date. They don't appear to offer an actual although the meter reading on the bill says "actual".

    Oct. 7 - Nov. 8 - read on/about Nov. 9: 67129, 719 kWh
    Nov. 8 - Dec. 7 - read on/about Dec. 9: 68122, 933 kWh
    Dec. 7 - Jan. 9 - read on/about Jan. 10: 69804, 1682 kWh
    Jan. 9 - Feb. 7 - read on/about Feb. 8: 71205, 1401 kWh
    Feb. 7 - Mar. 7 - read on/about Mar. 9: 72396, 1191 kWh
    Mar. 7 - Apr. 6 - read on/about Apr. 10: 73935, 1539 kWh
    Apr. 6 - May 8 - read on/about May 10: 74670, 735 kWh

    I didn't know if it would be helpful to note the room sizes? the living room and first floor bedroom are 14.5' x 12.5' with 7.5' ceilings. One of the upstairs bedrooms is 14.5' x 12.5' and the other is 10.5" x 12.5".

    I replaced all the windows with double pane windows but I still get some frost on the inside of the windows. I think because the house is so close to the ground there is a lot of humidity in here and condensation builds up on the windows in the winter. I believe that is what contributes to that cold damp feeling that never allows you to warm up. I work from home and last winter to keep my bills down, I dialed the heat down in every room and worked underneath an electric blanket, basically unplugging and replugging as I move room to room. I'd love to figure out a better way.

    Can I ask? the room-by-room Manual-J load calculation... does that have to be done when it's cold out?

    Thank you again.

  4. indoorsy | | #4

    also, thank you for the correction on the zone. I honestly thought the plant hardiness zone was the same as the DOE zone.. that's where I got the 6b. Clearly, I am an infant in this arena :-)

  5. Expert Member
    Dana Dorsett | | #5

    Manual-J estimates the heat load based on the construction details such as the construction materials, window types, estimated air leakage, etc. and can be done at any time (including before the house is even built, which is a good idea for new construction.) It's best done using the 99th percentile temperature bin as the outside design temperature, and 68F (the code minimum) as the indoor design temperature.

    In Manchester by the Sea you can safely use Gloucester's +5F 99% outside design temperature as an design temperature for sizing the equipment- it'll be close enough.

    I'm not sure how you read the meter on the 9th, but tabulate the power that was used only up to the 7th of the month. I'll assume the 9th was the actual meter reading date and usage for purposes of correlating weather data to energy use. Sometimes they will give you "average outdoor temperature during the billing period" information on the bill, which would be a useful sanity check.

    If you just take the Dec-9 through Mar-9 usage you went through 4274 kwh of electricity, most of which was for heating & hot water. Using base 55F degree-days from the Beverly airport (KBVY on it comes to about 1930 HDD. So for a linear approximation your heating constant is about 4274/1930= 2.215 kwh per degree-day. Converting to BTUs (x 3412 BTU/kwh) that's 7555 BTU/ HDD. In a 24 hour day that works out to (/12=) 630 BTU per degree-hour.

    The 5F outside design temperature is 50F cooler than the presumptive 55F heating/cooling balance point (the degree-day base temp) when heating only to 60F, but we'll add another 10F of heating degrees on the presumption that you'd like it to be closer to 70F, bring it to (50F + 10F= ) 60F heating degrees.

    So the implied heat load is 60F x 630= 37,800 BTU/hr, which is a credible number for a 1200' house only if it's very leaky, with almost no insulation (which may be the case.) For reference, that's roughly the heat load @ +5F of my 2x4 framed sub-code 2400' 1920s 1.5 story bungalow in Worcester, that has retrofit cellulose in most (but not yet all) wall cavities, ~ R20 in most of the cathedralized ceiling area, and clear-glass storms over wood sash antiques for most of the house, and R15 rigid foam on most of the ~1500' basement (in addition to the 2400' of above grade fully conditioned space.)

    So it's highly likely that you have a lot of low hanging fruit to pluck on the building envelope to lower the heat load before installing a new heating system! Getting it to under 25K should be pretty cost effective, or even under 20K. But if you're going to pull the trigger on some ductless before doing any improvements (or the Manual-J), a 2-ton 3-zone system is probably the biggest ductless that makes any sense at all for the "after" picture, without being grossly oversized. But do the Manual-J first.

    If the house is that leaky MassSave should have been all over you about air sealing and retrofit insulation (or perhaps you needed to steer the auditor in that direction). Some of their staff are more experienced than others...

  6. indoorsy | | #6

    Dana, Thank you... I do believe the building envelope is severely lacking... The house is modest and from what I could determine during my renovation, the original construction was poor. It was built in the late 80's and the construction methods appear to be the worst of what you'd expect from that era.

    I've had two Mass Save people over. The first was before i had a good handle on the issues here and the second fairly "green"... I should probably try again and ask for them to send their A game.

    I can't put a lot of money into improving my house as I won't get it out, so I am reluctant to tear the walls apart to add insulation. The outside is naturally weathered shingles (not clapboard), so not sure what the option is to add insulation.

    The first mini split contractor told me that for every dollar I'd spend on mini split energy, I'd spend five on electric baseboard heat. That tells me mini split is 20% of the cost of electric baseboard. The second contractor told me that the mini split would cost approximately 40% less, so even the cost savings on the energy varied so much! Really difficult to know which way to go. Both cost estimates were fairly similar. In the 12K range. I have the third contractor coming on Friday and they will be discussing the Fujitsu (vs. the other two, Mitsubishi).

    I am curious how to find a person qualified in my area to do the Manual J calculation? This is quite a bit more confusing than I even thought it would be. I'm glad I asked the questions and am getting the help but I am learning just how little I know about all of this. Reading through your post, Dana, I am stunned at how complicated it is. I hope I can get up to speed fast enough to make some decisions such that this is a comfortable winter. Currently in my living room, there are three baseboard heaters, but one is positioned so close to the thermostat that the other two don't come on. The one that does come on is furthest away from the couch where we'd sit to watch TV, etc.... Must need for improvement here.

  7. indoorsy | | #7

    Thank you Jon. It is quite windy here on a regular basis. From a home insurance perspective, I am in the flood zone being within 1/2 mile to the water. Flood zone more because of the wind vs. the water.

  8. Jon_R | | #8

    In a leaky house, I'd add something for more than average winds (even if they don't occur at -5F). Ie, maybe a 99% load more than 50K BTU/hr (as is).

  9. GBA Editor
    Martin Holladay | | #9

    The cost of operating a ductless minisplit in Massachusetts is likely to be about 1/3 the cost of operating electric resistance heating, but your savings might be somewhat less than that. My guess is that you misunderstood the second contractor. The contractor was probably saying that your electricity bill for heating with minisplits will be 40% of your electricity bill for heating with electric resistance. (That's different from saying that your savings will be 40%.)

    If that's what he said, then your second contractor was conservative -- and closer to the truth than your first contractor.

    If you had a monthly electricity bill of $400 during the coldest month, it's possible that about $320 of that was for heating. If your future heating bill is only 40% of your old bill, that means that the $320 will be cut to $128. If you add on another $80 per month for all of your other electrical loads, your monthly bill during the coldest month might be $208 instead of $400.

  10. GBA Editor
    Martin Holladay | | #10

    Q. "I am reluctant to tear the walls apart to add insulation."

    A. Cellulose insulation contractors can add insulation to your walls without completely opening them up. All that is necessary is to drill some holes -- usually one hole per stud bay. This can be done by carefully removing some of your siding -- easier on some houses than others -- or by drilling holes in your interior drywall. (Drywall is fairly easy to patch and repaint, although the work can be disruptive.)

  11. Expert Member
    Dana Dorsett | | #11

    MassSave subsidizes insulation to the tune of 75% as a rebate. Blowing the walls of a 1200' house with cellulose would likely cost you about a grand out of pocket, and take about one day. It would also reduce air infiltration by quite a bit.

    The efficiency claims of the most optimistic HVAC contractor was making for mini-splits is over the line of fraud. BEST case is about a 3.75:1 and 3: 1 is more typical, but if right sized 3.5:1 isn't hard to hit. A 5:1 improvement would be pushing the edges of the absolute best case ground source heat pumps.

    The 40% savings (~1.5:1) claim would be guaranteed even if the unit was grotesquely oversized for the load, but they may have been talking the whole bill, not heating-only.. Not all of your power use was for heating, so even at a 3:1 efficiency on heating the power bill would be cut roughly in half, not 2/3.

  12. indoorsy | | #12

    my goal today is to investigate how to get a more qualified Mass Save person in here. I very specifically asked about adding insulation to the walls as I truly believe that is the bulk of my problem. I was told that I was not a candidate based on what they saw.

    The entire back of my house is up against a large mountain of ledge - only about 2 feet between the ledge and my house - there are no windows on this entire side of the house and this is the wall that feels really cold. Sometimes in the winter I almost feel a breeze - maybe more of a draft but I've always suspected that long windowless wall is empty inside. Based on your suggestions it would be easy and cost effective to add the insulation (via the outside) since any repairs to the shingles will not be visible anyway.

    Adding the insulation might bring the electric bill down whether or not I add the mini splits.

    I did a bit more research and found a local company with many NATE certified technicians who are also Mass CEC installers so planning to give them a call today and get them over here.

    I really appreciate all of your advice. Thank you.

  13. Expert Member
    Dana Dorsett | | #13

    With apologies, I've been prettty sloppy in the analysis so far, since we haven't subtracted out other power use.

    We can try to refine the power use heat load calculation a bit to get a handle on how much of the power use was "other". I suspect your background non-heating power use is on the order of 600-700 kwh/month, and probably not less than 500kwh/month since you're probably heating your hot water with electricity. Assoming 1800kwh of that would bring that 4274kwh was background power use, it brings it to 2474 kwh over the 1930 HDD(55), which yields 1.282kwh/HDD instead of the 2.215 kwh. That would make the implied heat load a more reasonable:

    1.282/2.215 x 37,800= 21,878 BTU/hr

    Assoming the 600kwh/month for other uses is a correct assumption the ~22K @ +5F outdoors, 68F indoors is still a bit high for a 1200' house, but not insane. SOME amount of retrofit air sealing and insulation is still in the cards.

    But the 22,000 BTU/hr load also means that a 2.5 ton multi-split like the MXZ-3C30NAHZ2 capable of delivering 28,600 BTU/hr @ +5F may be a bit oversized for the actual loads of the house after tightening it up, but it would cover the load. At $12KUSD it's also a bit on the high side ($4800/ton!). In competitive bidding a 3-head 2 ton Fujitsu AOU24RLXFWH good for about 25,000 BTU/hr @ +17F (still over 20K @ 0F) would run about $8K, maybe a bit less.

    There are some ~1.5 ton 2-zone cold climate units like the MXZ-2C20NAHZ out there that are good for 22K @ +5F that might be more appropriate too, if better fuel use analysis or a Manual-J indicates the load is that low after tightening it up some:

  14. indoorsy | | #14

    hi Dana,
    I guess I thought the prices were a bit high as well. As mentioned, I don't suspect I will get out any investment I make in my house... It is more for comfort while I'm here. I suspect to stay here another 5 or 6 years. I do believe that anyone looking to purchase the house may be put off by the fact it is entirely heated with electric and so from that standpoint, the fact that it has a more energy efficient form of heating/cooling should help mitigate that concern. Additionally, if I am asked to provide utility bills to someone looking to purchase the house, they will (hopefully) be low enough not to scare a buyer off.

    I really have to watch out for over-improving.

    I've met with two contractors thus far and I have two other appointments set up. 3 of the 4 appointments are for Mitsubishi and the fourth for Fujitsu. I was noticing on the Fujitsu website that they have different types of interior options, not all wall hung units. I'm curious about that as it could be helpful, particularly in my son's bedroom to have something other than a wall hung unit.

    This has been a bit of an odyssey... I was set to go with the first person other than slight discomfort over one gigantic unit (in a location that wasn't really the best, aesthetically speaking) for the entire first floor. Having the second person in made me realize how much there is to this and I thought his ideas were better, but I question removing the existing baseboard heaters (as a way of not having to upgrade the electrical panel).

    Dana, that MXZ-2C20NAHZ... Can that take just two interior heads?
    I am still confused as to what is going to provide the most comfort and suspect that my first floor bedroom is not going to be comfortable unless I have a unit in the room, particularly since I like to sleep with the door closed because of light coming into the room.

    Dana, also thank you for doing that extra calculation... so far beyond my capabilities. I was curious what sort of kWh usage I had this summer. 646 in July and 544 in August. This would be for heating water, the electric dryer, fridge, lights and my daughter's window AC unit which she unfortunately forgets to turn off when she leaves the house and I don't always catch it. I suspect our usage would be a lot less without the window unit (I could be wrong though).

  15. Expert Member
    Dana Dorsett | | #15

    The ~600kwh/month numbers for July & August means that my guesstimate for your mid-winter "other" usage is probably not far off. The window-shaker AC probably added 100kwh/month to the summer bills, but hot water use tends to go up in winter and the amount of electricity used per gallon also increases with the much lower incoming water temperatures of winter. It's the right range, so it's pretty assured that the load at 68F indoors/ +5F outdoors is under 25,000 BTU/hr, and the 22K number may be pretty close.

    In most 2 story houses with equal upstairs & downstairs floor area the upstairs loads are higher than the first floor, due to the greater exterior surface area of the roof. There are many exceptions to this, but a reasonable working assumption for the sake of this discussion would be a that with a 22K whole house load the upstairs might have a load of 12-13K, the down stairs 9-10K.

    Since you have "....added spray insulation in the attic between the rafters..." and the attic venting is sealed off, the upper floor can be fairly easily served by a mini-ducted mini-split, once you have the room by room load number. Almost any individual bedroom will have loads well below the capacity of an individual half-ton head, but the whole floor (3-4 bedrooms?) can probably be served by a single 12RLFCD, or maybe even a 9RLFCD in the attic, with some short duct runs. The 12RLFCD is good for 16,000 BTU/hr @ +17F, and still over 12K @ +5F.

    The 9RLFCD is good for 12K @ +17F and over 9K @ +5F:

    While it's possible to hang RLFCD cassettes on multi-split compressors, efficiency wise (and upfront-cost wise) it's often cheaper up front to have two separate single-zone units for the upstairs & down stairs. Odds are pretty good that the loads for the downstairs is within range of a 9RLS3H, and almost certainly within the range of a 12RLS3H:

    I suspect a separate 12RLFCD mini-duct upstairs + 12RLS3H wall-blob downstairs solution down would come in around $9-10K in competitive bidding if done at the same time by the same contractor. If it can take 3/4 tonners for both it could be a bit less.

    For reference, I saw two quotes for the even bigger 18RLFCD mini-duct unit mounted in the attic coming in around $7.5K about a year ago, which is roughly the same cost of a 2-ton 3-head AOU24RLX, but more efficient due to the lower modulation range on the compressor and better match for the load,as long as the ducts are inside of conditioned space. The homeowner opted for the AOU24RLX in part because the RLFCD would have been mounted above the insulation, which takes a severe toll on the as-used efficiency.

    With an aggressive room by room Manual-J done it will be possible to zoom in on the options.

  16. indoorsy | | #16

    hi Dana,
    This is great information and I am reading it and reading it again trying to understand. Then referencing the links and the Fujitsu website such that I don't ask questions of you that I could try to answer on my own through some research.

    Having said that, I am not understanding a few things and hoping you can clarify:

    --- So, my understanding (from the first contractor who we now know has said some questionable stuff) is that the energy efficiency of a mini split system comes from the compressor being outside and turning the air outdoors into conditioned air inside. I guess, I thought the compressor HAD to be outdoors? It sounds as it you are suggesting that for the upstairs bedrooms, the compressor could actually be in the attic? If that is the case, would I still expect the same efficiency?
    --- To confirm, the attic is completely sealed with either closed cell or open cell spray foam insulation (can't remember which).
    --- I was looking at the cassettes but I think that won't work because the joists are 16" apart and I don't want to get into a bunch of construction.. .cost wise probably not feasible / advisable, BUT could I put the compressor in the attic and connect it to a wall hung unit? I am truly not understanding how all of this works. I tried to call Fujitsu but got connected to a voice mail.
    --- Both contractors were having a hard time figuring out how to get a unit into my son's rooms because of its location so this "compressor in the attic" scenario is of great interest. Also, may make economic sense as well.

    Thank you and my apologies for not keeping up with you intellectually. Once I really understand things, I'm there. For whatever reason the mechanics of this, the options, the efficiency, the installation, the prices... just so many different ways to go and its a little confusing.

  17. Expert Member
    Dana Dorsett | | #17

    "I thought the compressor HAD to be outdoors? It sounds as it you are suggesting that for the upstairs bedrooms, the compressor could actually be in the attic?"

    The compressor is always in the outdoor unit, sometimes erroneously referred to as the "condenser". While the outdoor unit's coil is a condenser while in cooling mode, the indoor unit's coil is the condenser when operated in heating mode.

    The indoor unit could be a wall coil, a ceiling cassette, a floor mounted coil, or a mini-duct cassette driving a limited duct system that serves a few rooms. A mini-duct cassette allows the capacity of the indoor unit to better match the load, which is now the load for a few rooms (or the whole floor) rather than just one tiny-load bedroom.

    A mini-duct cassette and ducts retrofitted into a sealed-conditioned attic would be mounted on top of the joists, not between them. It's not a huge construction project, but there is a bit of duct design work, duct installation & balance tweaking to be done, which makes it bit more expensive than a wall coil of similar capacity, but it offers the flexibility of distributing the heat to multiple rooms with one cassette rather than multiple wall coils. The tested efficiency is somewhat lower than a single-head wall coil type mini-split, but the Fujitsu units aren't bad- the -9RLFCD tests at HSPF 12.2, SEER 21.5 under standard test conditions, the -12RLFCD tests at HSPF 11.5, SEER 20.0, which is better than many wall coil models (if lower than Fujitsu's RLS3H series wall coils.) Fujitsu's mini-duct cassettes also have a bit more blower capacity than the competition, and can drive more ductwork (but it's still better for efficiency to keep them short, fat and hard-piped rather than flex duct.)

    This page has several pictures of attic mounted mini-split installations (even some mounted on steel strapping hanging from the rafters!)

    more here:

    What appears inside the room is pretty standard looking HVAC register grilles.

  18. indoorsy | | #18

    light dawns on marblehead!
    I actually get it now!!

    and now that I get it, I understand the beauty of what you are suggesting. the house is a very simple house with my bedroom on the first floor, my bed up against that long windowless wall (to which the outside unit will be mounted since no one will ever see it). My daughter's bedroom is directly above mine and the same size but her closet (huge, about 9 feet of closet space) is on that long windowless wall. My son's bedroom is above the first floor living room but not as big as the living room as there is a hallway that connects both bedrooms to the upstairs bathroom. The hallway runs along the long windowless wall so his room is a tricky since it doesn't have a wall in contact with where the big outside unit will go.

    This mini-duct cassette could supply both those rooms from the attic but now I am thinking it would also take care of my room if we run a duct through my daughter's closet.

    Then we just need a separate unit for the living room which is the area where we suffer most from the cold winters. The upstairs seems to get warm and stay warm easier than the downstairs so getting some decent heat into the living room would be my biggest goal.

    So what comes out of the ducts into the rooms, is that the supply? and there is a supply for each room and thus each room is a zone with it's own thermastat? And is it true there is only one return needed? Can the return be anywhere or does it need to be in the same room as one of the supplies?

    thank you again sooooo much.

  19. indoorsy | | #19

    just curious about one other thing...

    could a multi-zone outside unit connect to a ducted indoor unit in the attic which then branches off to the three bedrooms, each on their own zone, and then also connect to a wall coil in the living room? If so, does the outdoor unit need to be a two zone unit or a four zone unit?

    If a two zone unit is all that is needed - one feeding the mini-ducted mini split in the attic and the other feeding the wall unit perhaps I can get away with the 24K unit if Fujitsu?: AOU24RLXFZH and possibly something similar if Mitsubishi? It appears that only does two to three zones so I am just trying to understand what constitutes a zone.

  20. Expert Member
    Dana Dorsett | | #20

    Zoning a first floor bedroom with second floor rooms often has temperature balance issues in either the heating season or cooling season, sometimes both. It's usually better to zone by floor.

    For the bedrooms to be individually controlled zones means they need their own coil or cassette, which will almost always be oversized, sometime ridiculously oversized. Feeding 2-4 rooms on the same floor with a mini-duct cassette means they're all on one zone. Temperature balance between rooms on the zone is achieved by the duct design, with a few tweaking vanes, but individual room zoning with duct-valves such as those used in some larger split-system AC doesn't quite cut it with mini-duct cassettes. The return paths also have to be designed-in. Sometime it can be a ceiling grille at the top of the stairs or in a hallway, with a stud bay in the partition walls to the bedrooms employed as jump-ducts for the return paths (with grille near the bottom on the bedroom side, and another near the ceiling in the hallway or landing side.) Depending on the floor plan there may be other or better/worse options, so don't engrave this in stone just yet.

    You can probably do fine with a 2-ton 3 zone Fujitsu, with a 12RLFCD slim-duct cassette upstairs, a 7RLF in the downstairs bedroom, and a 9RLS or 12RLS head serving the open living room area. That may or may not be cheaper than doing it with two compressors, but the multi-split solutions are usually somewhat less efficient than single-zone mini-splits unless the single zone loads are too low.

    So, again... run the room by room Manual-J first, then you'll be able to come up with some more optimal solutions, and put them out to competitive bid rather than waste your time and the contractors' time with endless requests for proposals. It takes time for them to figure out what will work, and even if they don't get it right it still takes time. If you can tell THEM what you want they may still ask you to revise it (but they need to give a good rationale for it). But they won't have to spend the time figuring out a proposal from scratch. Their time is still worth money, and you'd be the one paying for it. Calling the same contractor back three times to bid different options generally raises their cost & your final price for the project.

  21. indoorsy | | #21

    spent hours looking into this tonight. my mind is spinning. I wish I understood so much of what I have learned before having contractors over so as to not waste the time of these people but the reality is, I have two quotes currently and neither do I feel confident about. I have another contractor coming tomorrow and had dealt with them when I installed a new mod/con furnace in my old house. I was very impressed with them then, so having them back and they are Diamond Contractor listed on Mitsubishi's website. Maybe the third time will be the charm or perhaps it will confirm what one of the other contractors discussed.

    I would say key to what I've learned is don't oversize the system. A wall unit is going to be more efficient than the ducted cassette but ideally I'd add insulation to tighten things up.

    Whether to do one on the first floor located in the living room and hope the heat/cooling reaches into my adjacent bedroom is still a question. I'd be willing to sleep with my bedroom door open if it was advisable to use just one unit on the first floor. My bedroom is just 180 square feet so I guess I am concerned with how to introduce heat/cooling in this room without overdoing it. I'd like the bedroom to be cooler in the winter than the living room as I sleep better when it's not too hot, but I'd like the room to be cool in the summer as I don't have a window AC unit being on the first floor and fearing an intruder so I am quite uncomfortable sleeping during the summer and being so close to the water it is pretty humid here a lot.

    Tying the kids rooms together seems like a good idea. Although one kid is in her room constantly and the other is never in his room so likely I'm paying to heat/cool a room that is rarely used.

    It's all very confusing but less so having learned so much through this forum and finally "getting it" allowed me to do some research on my own and learn more. It's hard to research when you have such a basic lack of understanding so I'm feeling much better and extremely grateful to you Dana as well as you Martin. Thank you.

  22. GBA Editor
    Martin Holladay | | #22

    You may want to read this article: Rules of Thumb for Ductless Minisplits.

  23. indoorsy | | #23

    Good Morning Martin, Thank you for the article. I read it, as well as the comments and additionally an article mentioned within entitled "The Diminishing Returns of Adding more Insulation" (in which you are mentioned!).

    To the degree that you have time to help me with understanding this, here are my thoughts...

    My building envelope will likely never reach anything approaching advisable or air tight. It was a poorly built house. When I purchased it there were weird lumps in the floor. Upon removing the subfloor, we discovered that the sonotubes which were supposed to under the beam were under nothing and the lumps were the house settling around the sonotubes. We added new sonotubes under the beam. This is just one example of the shotty build. When I bought the house there was a hatch in the floor in the kitchen , which led to a well for water coming in off the street. This was exposed to day light with much animal life under the house. Only a 1" blue foam insulation underneath the subfloor, much of which was scratched off by raccoons, etc. To fix the house, we dug a trench, installed a drain to wick moisture away, adding a foundation, poured gravel, poured a rat slab, adding a vapor barrier, plywood under the joists, spray insulation between the joists, plywood subfloor, new hardwood flooring. IT was A LOT! but keeps the critters out and eliminated the need for a separate heater in the well where the water comes in as that is now completely sealed and enclosed.

    The walls are another matter. Anywhere I could, we padded out to 2x6 and added spray insulation (the kitchen and two bathrooms). As mentioned previously the attic is completely sealed with spray insulation and I don't think there is much heat transfer up there as it stays fairly temperate in the summer and you'd think it would be sweltering.

    I guess I am wondering how much insulation can actually be added to the existing walls, through drilling of holes as you'd suggested (I believe the walls have batt insulation) and how far I can move the R value... Based on the article I mentioned above, even getting it to R12 or R14 would seem to make a difference. Where I am now, I don't know? Finding someone who come in here and tell me with some assurance??? You'd think having Mass Save in here twice, and pleading for answers, I'd already know that.

    The new windows were installed by me and are Andersen Woodwright and they did seal any gaps in the stud wall during installation. I also replaced the door and added a storm door as well as installed a new sliding door at the back of the house (in my bedroom).

    So, I've done a lot but I believe the walls are the culprit of air infiltration and I feel a bit defeated on being able to make big gains here without tearing things apart. I've tried to find articles about adding insulation to existing walls and everything points to a larger construction project and suggests padding out to 2x6 walls.

    Since I know the attic is pretty well sealed for air infiltration, would it make sense to install the mini ducted unit for the upstairs bedroom with supplies near the center of the room (i.e.: as far away from the offending walls as possible?)... Despite lower SEER and HSPF ratings, it might be more efficient than a wall hung unit since the attic is as tight as a drum??

    I have the trusted HVAC company coming today at 11. Should be interesting...

  24. Expert Member
    Dana Dorsett | | #24

    The reason to mount the mini-duct cassette centrally in the attic is to minimize the total length of duct runs. These mini air-handlers are pretty wimpy compared to those found on central-AC or hot air furnace systems, and long duct runs impede flow. (But they only use 10% of the power too.)

    The supply registers can be mounted near the center of the house (not the room) to minimize duct lengths, using the register grille design to optimize "throw". The return ducts or jump ducts are better placed well away from the supply ducts to avoid short-circuiting the flow.

    A typical 180-200' bedroom in an insulated 2x4 framed house without huge viewing windows will have a heat load @ +5F between 1000-3000 BTU/hr. The minimum modulation on some wall coil heads is 3000 BTU/hr, so it's basically never going to modulate, only cycle on/off, which takes a toll on efficiency (especially if it's also cycling the compressor unit). But a mini-duct cassette with the same minimum modulated output serving 2-3 room loads will have a MUCH higher duty cycle, and will modulate over a wider range of outdoor temperatures. An HSPF 10 mini-duct cassette serving three rooms will often beat three HSPF 12 wall coils on efficiency & comfort when the wall coils are all grossly oversized for the room loads.

    When rehabbing exterior walls, what sort of insulation (if any) was in there? Some of that can be inferred from the age of the house, but the quality of the installation is all over the place, but can be verified with infra-red imaging (often used in conjunction with blower door testing for finding out where the air leaks are.) If it's all medium-density R13 batts (1970s) and there are no glaring gaps in an IR image, putting more insulation in the stud bays would be more difficult and offer only marginal improvement. If it has 2-2.5" thick "econo-batts" , which were often used in summer homes in the 1950s & 1960s it's pretty easy to pack those out with quite a bit of improvement in both air tightness and R-value. If you have walls that always seem exceptionally cold (or even condense moisture on them) in winter it's likely that they have little to no insulation &/or leak a lot of air, easily verified with IR cameras.

    A good insulation contractor can usually figure it out even without the high tech tools, but an IR image showing where the gaps are is a good road-map for the insulation installers. As these tools get cheaper more contractors are starting to use them.

  25. RobInNorCal | | #25

    I can't help but wonder why someone (indoorsy, perhaps?) hasn't spent $5 on a drywall saw or razor knife and hacked a 6" square hole in the drywall of the super cold room? Easy to patch, and a first-hand look at the problem will short-circuit 10,000 words of 'might be' and 'maybe'.

  26. Expert Member
    Dana Dorsett | | #26

    A 3/4" round hole and a low-end sub-$100 borescope can do a lot too, and is even easier to patch.

    MassSave auditors worth their would be doing some snooping and poking around at things like electrical boxes & plumbing penetrations on exterior walls to get a handle on both the insulation type, and to get a sense of how good the air sealing detailing is. But they are usually working down a list, and unless a building deficiency is something that would be subsidized under their programs they will ignore it. It usually has to be GLARINGLY drafty before they offer up blower door tests and/or blower door directed air sealing (which is subsidized in worst-case cases), but it doesn't hurt to ask. ( ) The fact that the attic and subfloor under the first floor have been foamed may be lulling them into air-sealing inspection complacency.

  27. indoorsy | | #27

    I spoke to the builder today who did my renovation to ask if he remembered what type of insulation and we both recall the pink fiberglass batts. In that case, how do you dump cellulose on top of this?

    In terms of the existing heat... it just does not travel far enough to make any of us feel comfortable. I think part of the issue is that there are three lengths of baseboard in the living room and the thermostat is too close to one of them such that the others don't engage.

    Rob, good point about the exploratory surgery although I don't really need to see inside the walls to know that what is in there is inadequate.

    Now I am trying to fix this before winter comes but the reality is that mass save reps would likely understand the problem a little better if they visited during the winter.

    I am hopeful that I will get a quote combined with rebates that will be doable - maybe less than 10k. ?? I hope so and either way I'll keep you posted

    The meeting today went well. I've got another tomorrow (with the Fujitsu person)

  28. RobInNorCal | | #28

    No need to wait for winter. If you know what's in the walls, you can make a remediation plan; if you don't all we can do is conjecture. Cut a small hole and check; you might learn that it's worth taking down the drywall on the back (cold) wall, then fix the problem once and for all, Putting drywall back up sounds like a much bigger job than it is in fact, and drywall is pretty cheap.

  29. indoorsy | | #29

    Rob, Thank you for the encouragement... I got out my steak knife and tried to find an inconspicuous spot to cut open the wall. I spotted an old telephone junction box and unscrewed the cover and hit pay dirt. Just as suspected, fiberglass insulation. Now I know. I guess I am just surprised there was any insulation at all.

    I am very reluctant to take out the dry wall and replace the insulation. It seems really disruptive but there is the 75% off promotion with Mass Save to an unlimited amount until September 15th. I don't know if that includes repairing dry wall and painting?

    I've attached a picture of what i found.

  30. indoorsy | | #30

    I called Mass Save to ask if I could have another assessment with a more qualified energy technician. They have to open a case to ask for my information to be transferred to them since the people I had in were an independent Mass Save contractor. He said they will call in a few days and that as long as I schedule my assessment by the 15th, even if I don't have the insulation work done, I will qualify for the insulation at 75% off to an unlimited dollar amount (vs. up to $2000 if scheduled after the 15th).

    I guess I am going down the insulation road - not a place I thought I'd go but you all make a lot of sense.

  31. RobInNorCal | | #31

    Good job, Indoorsy - now you know that blowing more insulation into the wall cavity isn't a good option. I'll leave it to the more knowledgeable people here to suggest options that might make this room more comfortable.

  32. GBA Editor
    Martin Holladay | | #32

    You wrote, "The existing heat... does not travel far enough to make any of us feel comfortable. I think part of the issue is that there are three lengths of baseboard in the living room and the thermostat is too close to one of them such that the others don't engage."

    Without a site visit, I'm basically guessing -- but based on the information you have provided, I'm inclined to say, "Bingo."

    It's probable that you don't have a wall insulation problem. You have a heat distribution problem.

    Of course, there are ways to add insulation to your walls. But the fundamental problem is probably not the wall insulation.

  33. indoorsy | | #33

    Thank you Martin and Rob...

    I guess moving the thermostat is an option but it doesn't really address the extremely high cost of electric baseboard heat. I wonder if the mini splits would provide cost savings while also providing a greater degree of comfort. The living room is where we suffer the most - just never warms up. When I walk by the baseboard in that room that does work, I can feel it but you can't really feet it two or three feet away. It does little to throw much heat.

    I am somewhat concerned about the size and appearance of the mini split hanging on the wall both in the living room and in my first floor bedroom (which doesn't need one for heat as I don't mind sleeping in the cold but I like the idea of one in here for AC). It's a small house and I have it decorated very stylishly (imo)... so I've got to weigh the cost of installation vs. the cost of monthly heating bills vs. aesthetics vs. comfort vs. resale.

    It's a complicated equation.

  34. Expert Member
    Dana Dorsett | | #34

    With the pink stuff in the walls everywhere it's unlikely that you'd get huge improvement out of more insulation, but it still might be improved with air sealing if it's shown to be super-leaky.

    I agree with Martin that heat distribution is probably a large contributor to the comfort issue. A mini-split will keep the air moving for better distribution, and will also reduce the power bill, even if you "set and forget" it to 70F, well above the temperature settings you've been using with the baseboards.

  35. indoorsy | | #35

    love that idea. 70 degrees, set it and forget it, lower bills.
    i have the contractor who deals with fujitsu coming over today.
    i guess my new feeling is to get this done as inexpensively as possible.
    stick with a condensor that can get all the rooms done without a branch box. choose locations that don't require crazy acrobatics on behalf of the installers. (that was the case with the second quote which came in at $16k before rebates... all sounded so good but i don't really want to spend that much and have since gained some great ideas of how to get this done in a simpler / less expensive way).

    I'll keep you posted.
    thank you

  36. indoorsy | | #36

    had the contractor over who deals with HVAC and he was head and shoulders above everyone else i have met with (three others)... it takes so much time and effort to set up these meetings and I hate wasting people's time but honestly I am glad I kept going with seeing who is out there and what they have to say. I am praying his price is equivalent or better than the others, but even if it was a little more, I would likely go with him so from his understanding of what I'm trying to do here. He said that as a past customer he would do his best to be reasonable with the quote.

    He was the only one of the four who measured the rooms, windows and doors so he can do a heat loss calculation. I asked the contractor yesterday if he planned to do a calculation and he said it was not necessary.

    He was also the only one of the four that suggested adding a Rinnai Tankless Water Heater with the addition of a small propane talk outside to fuel it as a replacement for my electric water heater. He said there are rebates and it would save a lot in electrical costs and that I would be looking at about $500 per year on fuel costs. My hot water heater is about 7 years old so not necessarily something I need to do immediately. But something to consider and he will provide a separate quote for this.

    it is really amazing, the variety of approaches out there.

  37. indoorsy | | #37

    in last post meant to say contractor who deals with Fujitsu.
    sorry so many posts... just very thankful for all i learned here.

  38. Expert Member
    Dana Dorsett | | #38

    At MA pricing/rates condensing propane isn't always cheaper than standard efficiency electric tank, and it wasn't too many years ago that it would have been over 2x the price of energy If you need to free up the floor space there may be a rationale for a propane tankless, but with the upfront cost and higher maintenance and likely higher energy price going forward it's unlikely to be a cost savings over electricity- quite the opposite. Trading a reduced electric bill for a propane bill bigger than

    Propane at 95% efficiency:

    91,600 BTU/gallon x 0.95= 87,020 BTU/gallon, or (1,000,000 / 87,020= ) 11.5 gallons per million BTU (MMBTU) At recent pricing of ~$3.10/gallon ( ) that's $35.65/MMBTU.

    Electric tank, EF0.92 :

    3412 BTU/kwh x 0.92= 3139 BTU/kwh, or (1,000,000 / 3139 =) 319 kwh/ MMBTU . At recent MA average pricing of ~20 cents/kwh ( ) that costs $63.80/MMBTU

    So while the cost of hot water with an electric tank is currently ~1.8x the cost of condensing propane, heating hot water with a heat pump water heater would be cheaper, once your heating the house with heat pumps. But assume maintenance of at least $50/year for the de-liming the tankless every few years, and if (like many small volume users) the propane folks knick you $5/gallon when the going rate for bigger volume users is $3 (I know a few people who have been in that boat in recent years) even the fuel cost savings don't add up to much.

    A savings of $500/year would happen if you're using ~15 MMBTU/year, or 166 gallons of propane per year for heating water, which isn't customer most propane dealers are very interested in supporting at a low margin on the fuel, so it's likely that your costs will be well over the $3.10/gallon state average.

    Keep it in mind, but it's worth deferring that decision for now. It's typically $2-3KUSD to install a decent tankless, and if your time horizon is 6 years it'll be at best a break even deal. Most electric tank heaters are good for a dozen years or more, and a replacement is well under a grand. If it's in a big enough room to support it, MassSave also rebates heat pump water heaters pretty heavily.

  39. indoorsy | | #39

    point well taken Dana. Thank you for your analysis on this. I had not inquired about the cost of the heater but if it is in the range of $3-6k, I'm not up for that especially after putting in the mini splits.

    i cannot get a heat pump water heater as the spot where the water heater is, (and it is the only spot it can go) is too small for the air clearance needed. Literally no where else for it go as there is no basement here.

    hopefully the hot water heater I have doesn't start leaking as it will ruin my beautiful hardwood floors that I installed 3.5 years ago when I renovated. I wish these heaters gave you some sort of warning other than leaking. do they?

    thank you

  40. indoorsy | | #40

    hello all,
    I received so much help from you all...

    In total, I met with four HVAC contractors about installing mini-splits. I got a good feeling from two of the four - one would be for a Mitsubishi system. The other would be for a Fujitsu system.

    In both cases, I like the idea of a wall hung unit in the first floor living room, a wall hung unit in the first floor bedroom and then a unit servicing both the kids bedrooms on the 2nd floor. This would be a mini-ducted unit in the attic with duct work to each of the two bedrooms.

    Both prices are nearly identical so now I am in a bit of a pickle trying to figure out where to go from here.

    The Fujitsu would be two compressors on the outside of the house (in a spot no one can see so no big deal from an aesthetic standpoint). The Mitsubishi would be one.

    If you don't mind, here are the specs of each of the quotes. Can I ask, what would you do given the price is identical?

    Fujitsu Quote:
    1. Fujitsu Model # AOU12RLFC Single Zone Condenser
    2. Fujitsu Model # ARU12RLF Ducted Mini Split for the 2nd Floor Bedroom
    3. Fujitsu Model # AOU24RLXFZH Multi Zone Condenser
    4. (2) Two Fujitsu Model # ASU9RLF1 Wall Mounted Air Handler for the Master Bedroom
    and Model # ASU12RLF1 – for the Main Living Area
    5. Insulated Line Set with Line Set Cover
    6. Upon Registration, 10 Years Manufacturer’s Warranty and 1 Year Labor Warranty
    7. Wall Brackets for the Condenser
    8. Condensate Lines
    9. Miscellaneous Parts and Fittings
    10. All work to meet or exceed State and Local Codes
    11. This Proposal includes all Materials, Labor, Electrical and State Sales Tax

    Mitsubishi Quote:
    We will furnish and install (1) MXZ-3C30NAHZ-2, 30,000 Btu, multi zone condenser unit
    piped to the following (3) indoor evaporator units.
     (1) Second Floor Kid’s bedrooms, attic ducted air handler unit: SEZ-GL15NA-8
     (1) Master bedroom room wall mounted at right of slider: MSZ-EF09NA-8 Designer white
     (1) Living room wall mounted a back wall: MSZ-EF09NA-8 Designer white
     (1) Hyper Heat Pump Condenser mounted at the rear of the home: MXZ-3C30NAHZ-2

    The systems will have complete fit out of piping with white Slim Duct enclosure, drains to
    suitable locations, condenser wall bracket and all hardware to secure all the equipment. We
    will install a supply outlet into each bedroom on the second floor. A single return will be
    installed in the hallway. Note the attic must be clear of personal articals for work to be
    competed. Exterior piping will run at the rear of the home and at the left of the slider door.
    Our price includes all labor, materials, remote controllers, start- up and a one year installation
    warranty 100% plus 12 years on compressor and parts and 5 years on controls from

    any gut reactions to help me make this decision? I like both sales people. The Mitsubishi contractor has better yelp reviews and an A+ rating from the better business bureau with 103 reviews. The Fujitsu contractor had some bad one star yelp reviews but mostly related to their oil delivery division.

    Thank you.

  41. Expert Member
    Dana Dorsett | | #41

    The minimum modulation @+47F of the MXZ-3C30NAHZ-2 is 7,200 BTU/hr

    The minimum modulation @+47F AOU24RLXFZH is 6,800 BTU/hr, plus another 3,100 BTU/hr for the AOU12RLFC for a total of 9,900 BTU/hr

    It's not a huge difference but (in theory at least) the slightly lower minimum modulation of the Mitsubishi would mean slightly more modulation in the shoulder seasons, for potentially slightly higher efficiency. But with the Fujistu solution you could turn one of them completely off.

    It's a tough call, but another factor that may tip the balance is that there seem to be more Mitsubishi installers than Fujitsu installers in most of eastern MA, and Mitsubishi has a regional design center in Southborough, MA, which gives some confidence in the level of product support if there are any performance or design issues with them. (Not that Fujitsu installers are rare- they're ubitquitous, just not as ubiquitous as Mitsubishi in this part of the world.)

  42. indoorsy | | #42

    thank you Dana.
    I am sort of tending to think I'd go with the Mitsubishi. I looked at another of my Mitsubishi quotes and realized it was about $1000 less than the one in hand that I am thinking of going with. The salesman for that company wasn't nearly as professional. Basically came in and asked me what I wanted to do. ummm... aren't you the hvac contractor? But I realize that he is not the installer so although I got a bad vibe from him, doesn't mean it won't be a good outcome. I had used this particular company at a previous home and they did exemplary work so actually this is the only company I have hands on experience with. Wish the salesman had given me a better feeling.

    Martin?? any thoughts for me? anyone else?
    I'm so confused.

  43. indoorsy | | #43

    this is the other mitsubishi quote which turns out to be about $1300 less (not $1000) as mentioned above. that's real money!


    Ducted and Ductless Splits
    Air Handlers, Condensers Coils:
    (1) Mitsubishi MXZ3C30NAHZ2U1 Hyper HP condenser multi zone
    (1) Mitsubishi MSZFH09NA wall mounted hp air handler (lr)
    (1) Mitsubishi MSZFH06NA wall mounted hp air handler (mstr br)
    (1) Mitsubishi SEZKD12NA Ducted attic mounted hp air handler (second floor br)
     Furnish and install a complete ductless split system for home including all required
     Attic system shall be installed most practical method for future storage
     Ductless units shall be equipped with wireless remotes
     Wall mounted units installed in areas field coordinated.
     Condenser shall be wall mounted with manufactures approved bracket.
     Installation of properly sized supply branches to each bedroom on second floor.
     Installation of a properly sized centrally located return including filter grille for convenient
    changes from hall.
     Installation of vibration isolation for attic system.
     Refrigeration line sets shall be field coordinated and encased in a vinyl protective cover.
     Wiring to the Existing panel commandeering living room circuit for equipment.
    Installation Includes:
     Power and control wiring connections to applicable components.(allowance $800.00)
     Permit Fees billed at cost.
     Freight allowances
    Installation Excludes:
     Drywall,carpentry,painting.

  44. GBA Editor
    Martin Holladay | | #44

    I think you have milked GBA for all possible inputs and advice. Now it's time for you to make a decision.

  45. indoorsy | | #45

    i understand.

  46. indoorsy | | #46

    I just wanted to provide an update... I am normally a decisive person. I do my research and then make a decision. This mini-split thing put me through mental gymnastics like nothing else I've done at my house. The desire for warmth is so strong. But I just cannot wrap my head around the big white plastic box on the wall. Plus the $13k investment.

    I'm considering getting a propane tank and installing a gas fireplace. The heat needs are primarily in the living room. The rest of the house is fine. The mini splits offered AC which is something we'd love to have (but not as much as the heat in the living room). I can look into installing AC as a separate matter.

    I realize this is a green building forum and that the direct vent gas unit is not as efficient as the mini split but I think it might save me a lot of money on heating costs, plus I believe it will be very attractive and aesthetics are very important to me. The installed cost of the fireplace is $4k (plus carpenter's cost - I have someone good and cheap).

    You all offered so much help and so I thought I would just check back in with an update of my current thinking. I am attaching a drawing of my idea for the design.

  47. indoorsy | | #47

    sorry, file did not attach

  48. indoorsy | | #48

    Here it is

  49. PatriciaCranberry | | #49

    Indoorsy: Good luck on your project. Dana Dorsett...I'm trying to find someone to HIRE for a third party manual j calculation/equip selection recommendation. Are you available? Lets talk cost.... Martin...can you tell Dana I'm looking for him?

  50. GBA Editor
    Martin Holladay | | #50

    Here is a link to an article that addresses issues surrounding hiring someone to perform a heat load calculation or to design a heating system: Who Can Perform My Load Calculations?

  51. PatriciaCranberry | | #51

    Yes...very encouraging until you actually try to pull the trigger/write a check.

  52. PatriciaCranberry | | #52

    You should write a follow-up article titled who will perform my load calculations? I'm quite frustrated but I refuse to throw out the advantage I've gained by following many green building techniques just because I can't hire a third party HVAC design%

  53. Expert Member
    Dana Dorsett | | #53

    For the record, I'm not in the business of running Manual-J load calculations, and don't carry credentials that would pass muster with Massachusetts efficiency rebate programs that require Manual-Js even if I did run those numbers for someone. (I've seen some pretty sloppy & suspect Manual-Js that did make it though, complete with a licensed P.E.'s stamp on them. :-( Most from energy-nerds companies are pretty good though.)

  54. user-602763 | | #54



    Curious to know which system you end up installing and how much savings ?

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