Thank you for the responses! Brian Knight ~ Our home is one level (on a slab) with three bedrooms. It will be an open floor plan, just over 2,000 sq.ft. When I said "relatively" air tight/energy efficient I was referring to our quest to balance efficiency with using healthy materials (not a fan of spray foam for example). We do want to be mindful of proper ventilation/air exchange and have looked into doing something like this (copied from http://homeenergypros.lbl.gov/group/1000homechallenge/forum/topics/panasonic-whisper-green-w-ductless-heat-pump?xg_source=activity): "Some minisplits may have a small ducted system. Dave Robinson, www.GreenEarthEquities.com buys foreclosed homes in central California that he renovates, using two,1 ton Fujitsu mini-splits. He ducts one to the bedrooms and bath with very limited ductwork located in the hall ceiling. The other unit is ductless, and conditions the living room and kitchen of the one-story ranch homes. There are significant cooling loads with lots of 100 degree weather. His approach of combining ducts and ductless results in simple systems and homes with low energy bills. Dave has case studies posted on his website." Reply by Dave Robinson on August 31, 2011 at 10:12am "To be more exact, we use one outside unit (2 ton is the smallest they make in this model - so we use it on everything). One inside unit is the conventional mini split high on the side wall in the main room ... the one that everyone associates with mini splits. The other inside unit is mounted on the ceiling at the mouth of the hallway & delivers air to all the rest of the rooms thru a small duct system that we mount on the existing ceiling of the hallway. So the unit and all the ducts are inside the envelope. Then new drywall is added, reducing the hallway height about 10 inches. We throw the factory filter away and allow a 20 x 30 filter grille right under the air handler to provide a lot more filter area as well as access to the unit without breaking the building envelope. You can see pics of this hybrid duct design at A Good Business? How Long? Plus Ducted MiniSplit Update (Click the right arrow on the photo in the center of the page and it will take you thru a few other slides from that webinar and you'll get to the Mini Split photos). You'll notice we use galvanized pipe. That, along with the oversized return keeps the static way down which is essential for efficiency on these units. This unit has now been in two years. The owner loves it. Zero problems. Has utility bills less than half of his neighbors. This job also used a Panasonic ERV. We mount the ERV very close to the return of the ducted system and in the pick-up area of the wall mounted unit so all fresh air is circulated by the main system with no additional equipment needed. It works well for us and we have adopted this as our main system. It's the one we specify every time unless we are keeping old equipment that's not too old or too over sized for after our renovation. You'll also notice that we mount the outside unit on the roof instead of on the ground. Lots of reasons." We are thinking this might work with our floor plan: Kirkhall ~ Thanks for sharing your personal experience. I have read more on the HVAC forum. My interest in posting here was to see if ductless mini-splits were at all a preferred choice by those building new homes versus just being used for retrofitting/new additions. Niteshadepromises ~ "Based on all my research the operating costs are pretty substantially lower which we're looking forward to and hopefully might offset the initially higher install cost." This is in line with what we are thinking too! Good luck with your build! David Cary ~ The tax credits are wonderful, however, there is that pesky problem of having to pay upfront. With some budget reworking, this may be possible. However, my concern relates to your comment, "But I'm not sure getting all fancy is worth it.... R20 net walls, good southern exposure with some thermal mass. You won't need that much heat and you shouldn't need a/c." We don't want to pay for more than we need. The difficulty for us has been determining what our need is when factoring in the passive solar. I also agree with: "I've thought about this a lot and I don't know how cold you get but if you have total control of design and southern exposure, your best bet is lots of solar planning, tight house with thick walls. Cover the windows well at night. Then put the money in PV. Code will require too much of minisplits to be cost effective." To satisfy code, what would your recommendation be for a thermostatically controlled system that is reasonably efficient and cost effective (presuming we could swing the PV)? With good solar planning, another viewpoint is to put in some baseboard heaters to satisfy code. Is this reasonable or silly? Dekeoboe ~ I'm interested to know what you chose and why? Flgargoyle ~ As our heating and cooling days are very similar, it's good to know that you think it's a viable option. Though it seems I'm in the minority, I don't really mind the look of the wall units. Maybe it's because I don't find vents and returns all that pretty! Lori in the NW ~ Thanks for your opinion ~ they certainly are not for everyone! This post was edited by daisyblue on Fri, Feb 22, 13 at 17:45

Update. The unit was excellent this year. My guessitmate was between $300 and $350 on heating from oct to may. It was still making 110 degree heat at -9 . I did notice the rest of the house was chilly when it was around zero. The defrosts every 45 to 55 min were noticable when it was that cold Anyways that got me thinking about adding another unit to help ease the work during the single/teens temperatures on the unit and having extra heat. The only problem I do notice is since my unit I have know cycles too much when its in the 50s so a smaller unit for heating with a smaller low end heat would help, I am not worried about ac end since I was able too use one 5000 btu and sometimes two 5000 btu units to cool the house before. So I've been looking and seen the MSX muti zone units are out and new single units are out. First basement has not heat and stays in the middle 40s in the winter and around 64 ish in the summer. There a lot of mositure and a dehumidfier doesn't really work well until mid summer. The rafters are insulated (r13) and some of the walls are too. Anyways I was thinking of possibly adding a air handler down there for heat either a .75 or 1 ton. The main floor (drawing above) I was debating on a unit in the dining room (.75 ton) to heat the dining room and the kitchen. The kitchen was 60 during the negative degree days with the radiant heat set at 60. When it was in the upper teens it would stay around 63. Then the spare bedroom I was thinking of putting a .75 ton unit to blow out to the hallway and push air to the bath room and bedroom. The spare bedroom was set to around 50 with the radiant and the door shut while the other bedroom I used a box fan to push the cold air down the hallway and the warm air would enter above. I'm debating on heating the basement and if I do `I was think a 20,000btu dualzone for one area on the main floor and one down in the basement or do a 24,000btu tri zone and heat all the areas listed. Or I could do one of the single zone units (FH9000btu) and just heat the basement area or on the main floor since they are the most cost efficient though.

> Is it cold and/or damp where you are? I'm in the Boston area — so in a word, "yes". > Is your system perhaps oversized for your home? Not according to my HVAC contractor, nor according to the beOpt simulations I ran. But that said, it's only in the 50s outside, so I would not expect the system to be working hard at this point. It's sized to handle 4 seasons, and the compressor is rated at 30 kBTU >I think error codes for Mitsubishi mini splits are displayed on the remote control and the control board on the outside unit. What is the model number of your outside unit? It's a MXZ-3C30NAHZ2-U1. I don't see any errors on the remotes, but I'll keep my eye out! > Did you install this mini split yourself or was it done by a HVAC contractor? I am not a mini split expert, but what you are seeing is not normal operation in my opinion. If there is an error code then you may be able to use the service manual to troubleshoot the problem. This was installed by a Mitsubishi certified installer who came highly recommended. That said, the install went quite poorly and I would not be at all surprised if they screwed it up.

@fsq4cw - how about a ballpark price just for the air-to-water heat pump? Just out of my own curiosity. Note that due to @mtvhike having a fairly large solar array and the specifics of his tariff scheme, I'm not sure that any significant capital cost to reduce his electricity usage will pay off well. This shows one of the oddities about specifics of solar tariffs. As I understand the way it works is this: his base tariff for electricity is 9.5 cents/kwh. Any solar he generates offsets the electricity he consumes (calculated annually?). BUT: any solar generated in excess of consumption is only paid at the wholesale rate, which is dramatically lower than the retail rate (call it 1 cent / kwh). Right now - without full year data - he expects to consume somewhat more than his panels generate. The upshot is that his savings from reduced consumption are limited (You could analyse this differently but I find it easier to just take what he already has as the base case, I think the conclusions are the same). Let's say, for example, he consumes 4,000 kwh annually more than he generates, for a bit less than $400 (netted out annually). If he saves more energy than that, every 'extra' kwh saved only gets him 1c / kwh. At least unless or until he adds some significant extra load, like buying an EV or putting an aluminium smelter in his garage or something. So: I'd say it makes sense to consider a minisplit primarily for the air conditioning comfort and if it also offsets some of his straight resistance heating, great, there's some modest savings there (within a 'limit' of however much his consumption currently exceeds his solar generation). Spending much additional for the 1c/kwh savings just won't make much sense financially. This is pretty simplistic as right now he has historical data for consumption and the solar array is relatively new so annual generation only estimated, and of course from year to year both may vary. And at any rate, a good argument to not rush into anything with high upfront expenses or to prioritise other projects for the time being.