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

Mini Splits have been around for years++. What U hear about them are how incompetent installers install them. Try www.mitsubishicomfort.com/ the best ..they have some very good systems. Make sure you talk to a mitsubishi rep. not a hvac contractor first. asked the rep to refer U to one of there best contractors...thats the best way to "get it right" These are pricey products. But excellent. They have systems that have one outdoor sections and upto 8 indoor coils. As far as heating with hot air into one room this is not a solution. As far as concrete floors...thats what is horrible! I just finished redoing a floor. Replaced the entire house with Platon, and hardwood.

Hello, Would like to know how many BTUs (for 1 wallmount system)would I need for two floors of 690 sqfeet (each floor). The Unit will be on the 2nd floor in the middle between 2 bedrooms and a washroom (over washroom door facing master bedroom). It will be a dual split system. ------------------------------------- Also would like to know which is a safe reliable cost efficient brand, example of wall mounted (split systems) air conditions I've heard of: Fujitsu (they give 10 years warranty parts and labour) Mitsubishi (6 yrs parts and labour however been making them longer) Daikin (6 yrs parts and labour) Igloo York Carrier Grey All about the same price... ----------------------------------- Finally, is it better to get a dual system (with heat pump), from my understanding they are almost the same price and the advantage is that it has a variable BTU which may save some $$. Since the heat pump will be at the higher level then it wont heat as much however it is coming at about the same price. Then again more electronics in a system more chances of malfunctioning sooner? Thank you, Stelios

Thanks for your help, zL700; I like your link for SlimDuct enclosure, much better than my idea for 3"-4" pvc pipe! I plead guilty to a LOT of sharing! Once one reads all the way to the end, my question in the first line was 'history' : "Can anyone support my argument that it is ample to use a dual split unit for just the front two bedroom's? " This would save both cost and a difficult condenser install location. In short: We have a MrSlim MSZ-A17NA single-split 17 Kbtu unit for the 3rd floor finished attic, and a conventional 28 Kbtu ducted unit on the first floor. Our calculated 50 degree day heat loss for the entire house is 48 Kbtu, of which the two rear small bedrooms are only 5 Kbtu each. I have agreed to put in a dual-split 9+9 or 12+12 for the two 2nd floor front bedrooms. Shouldn't this effectively cool the entire 2nd floor? I need technical, experienced opinion to support my desire to avoid having to put in a 3rd condenser in the larger of the two rear bedrooms. Thanks to All - - Old Salt Details were dated SEP 3, 2307 hours.