First off, 4 stories sounds like a big vertical head for residential mini-split equipment just from my casual notice of those requirements. I would check that out first. I am testing a whole-house mini-split installation right now (Mitsubishi, 7 in, 3 out). I will let you know in a year or so if I like it ;-) On paper they are more efficient due to inherent efficiency and the inherent zoned nature. We have been having pretty hot weather and with my wife out of town this week, I have been pretty much been cooling the bedroom and the kitchen with some intermittent cooling in the utility room where the exercise machine lives. Note that I am not much of a sit and watch TV type. You are really a leg-up over lots of others on this decision as you have experienced mini-splits. One thing to think about is that, IIRC, most of them don't have back-up heat so you will not have any heat while they are defrosting. (Maybe none of them have electric resistance back-up, but I think I ran across at least one brand that does.) You also have to pay close attention to cold weather performance for the mid-Atlantic region. I know that with Mitsubishi's current residential equipment, the 1:1 systems have better low temp performance than the multi-splits. They are more efficient too. Even if they do have back-up heat, you can kill the efficiency pretty fast if you need back-up very often. Keep in mind that there are lots of options to the wall-hung indoor units. They cost more, but there are units that can be dropped into ceilings and others that sit on the floor. There are also short, ducted units that would solve that big room problem by splitting the supply and return. (You could also install more than one indoor unit/room.) Condensate needs to be dealt with using pumps. I am not an HVAC or building pro, so take my observations with a grain of salt. After replacing a ducted system with mini-splits, and talking to my install guys a lot, here are some observations and conclusions. Installing a mini-split through outside walls, as is it usually promoted, is pretty quick and straightforward (read fast and cheap) compared to installing a new duct system in an existing house with no central AC. My install was done through interior walls running the lines/cables under the raised house and out to the side which was much more complicated. If I were doing this over and I had a good duct system within a house envelope, I would stick with it. The trouble is, what is a good duct system? More often than not, they are outside of the living space. In addition, they are considered good when they leak 5% of the air and they only get worse as they age. My system was in the attic with parts of the duct system in the attic and partly in a furred-down space over the hallway. The worst part was one duct that started at the AH in the attic, dropped down under the house in a chase and ran for about 30 feet before it reached the first floor register in an addition with a flat roof (thus no attic). It then reduced in size and ran another 25 feet under the house. That part might have been mini-splitted even if the rest of the house retained a ducted system. By your description, your duct system was not installed very well, but if the design is sound, it could be revamped less expensively than installing minis. In general, I think that ducted systems are trickier to design and install than mini-splits so there is more tolerance for less than careful and knowledgeable installers with mini-splits. Due to their ability to handle variable loads, choosing the right size is not as critical either. (I had 4 tons cooling plus a gas furnace before, now I have about 106% of the cooling and 60% of the heating. The heating was way oversized.) My system will handle cooling fine with the house the way it is, but I should not have trouble after I make improvements to limit infiltration and add insulation. My installer is knowledgeable, smart, very workmanlike, and experienced (he has taught the trade for 30 years). He would have installed new ducts and a two-speed system for a slightly lower price than the chosen mini-split equipment. I doubt that he would do it for the same price if doing it on a similar home going through interior walls. He did not have much mini-split experience and brought in a collaborator that does, on this project because he was looking forward to a learning experience. I don't think that he lost his shirt, but I don't think he made as much as he usually does.

I just purchased 2 split a/c systems as an upgrade from the units I currently have. It is now September 22, 2014 and I am unhappy with my 3 month old brand new units. I started with a Fujitsu 11000 btu in the master bedroom and a Mitsubishi 30000 btu in the living room. The Fujitsu was weak in cooling efficiency and even though I cared for it very well it required cleaning and servicing every 6 months. The living room was an older model - but if you set it at 71 degrees - we'd be freezing within the 1st hour. Both eventually had freon leaks. I replaced the bedroom with a 2014 Mitsubishi 15000 btu thinking I could run it on a low and quiet fan setting at night. The living room was changed to a 36 000 btu 2014 Mitsubishi which I was also hoping to run on a quieter setting. But - NO! We are running both of these units on MAX 59 degrees on a high fan to cool either room which takes a couple of hours. The air feels cold coming out of units - but not too far from the units. Recalled the installers and checked the freon, temps, and the workings of these. 2 month old units. "everything is Normal". Tech says that's how these new energy efficient units run. He says you gotta run them on max to start with or before the house heats up during the day or close the doors down the hallway to trap the cooler air in the living room. The bedroom is the same - we sleep at 9pm - so we run it at 7pm - on MAX!! It sucks - in Hawaii both units plus the install $6200. My electric bill is slightly higher because these energy efficient units run longer and on Max!!! So disappointing! I have tried different temp settings and combinations of fan power. Some have suggested that in Max mode- it is bouncing the cold air off the opposite wall back to the unit causing the thermostat to raise the temp. I am baffled - so junk !!!

I am loosing my mind or someone deleted my statement that I live on the (South) Gulf Coast! That is a very important part of many of my comments on house issues. It is obviously very hot and humid here. Your BC situation is so very different so I can't really speak the practical side of your heating issues. No, I did not install it myself. I got a guy that's been teaching at the local trade school forever as far as the local installers go. He did not have much experience with minisplits and called in a collaborator for the job. They did a really nice job running the tubes and electrical through interior walls. The house is raised over an open crawl space so I don't have anything but the outdoor units visible outside. Now I have three whereas before I had two conventional two-ton compressors, one AH, with a gas furnace in the attic. I mostly looked into Sanyo, Toshiba and Mitsubishi. They all have advantages and disadvantages wrt operating features. I do not know your climate so my main concern would be low temp heating performance. Here if you have enough cooling in a heat pump, you can not really run out of heat. One thing I have noticed, but don't understand is that the single minisplits are more efficient and better at low temp than the multi systems. There has to be an engineering explanation or they are just a year or two ahead with the single systems and the designs will trickle over with a delay. Overall, we really like the system. It fits our lifestyle. We are out a lot, and the house has its original doors and walls intact. The inherent zoning feature should save us a lot of money over the years since we will have less expense for conditioning of rooms that are not occupied at different parts of the day and night. My systems are mounted high on the walls. It was very cold for my area when we went into operation so it got a good test. One thing that I noticed is that the programming could be better for heating. The inside blowers go to slow mode when the temp approaches the set point. This makes them good ceiling heaters. (That seems pretty predictable. I've lived in homes in predominantly cooling climates with both supply and return located in the ceilings.) Bumping up the blower speed manually solved the problem. I suppose that the ceiling fan might have done the same thing. One thing I am very glad that I did was to change the first plan to put the units at the head of the beds in a couple of rooms. I was actually concerned that the cool air would cascade down on heads at low blower speed. That might have been a problem, but it would have been even more annoying to have hot air on the face in the "winter". Keep in mind that you can mix and match. If I had not gone entirely with minisplits, I would have had a regular forced-air system and installed one mini in the rear utility room. The duct to that area originated in the attic, ran vertically down a chase through the house and under 2/3 the length of the house to three registers in the floor in that room. It was a weak point to keep in a main system. The expense of mixing systems like that might depend on how capacity breaks down in choosing a "main". Finding a good installer who is experienced with minisplits might be difficult.

Elmer's inquiry deserved more of a answer than your chest-thumping, self-promoting, California-bashing commercial. The climate around Katy, Texas is certainly not "one in a million." It's similar... Just "similar" but not exact... meaning different. Me and Mr. Fudd's disagreements are well documented on this board the story continually evolves from duck to rabbit season and back again. One in a million is a generalized comment... a saying. But you Mr. Ross love to find something to argue about for the sake of arguing. Distinctly different? That's rich. I find it humorous to what people like to nit pick over. It doesn't change anything. I don't change anything about the comment I made. You can disagree if you want, I still say Katy, Texas is indeed "one in a million"... at least. Ray is a one-person company. He lives in the replacement contractor world. When someone is without heat, air conditioning or hot water, it's often the first replacement contractor to arrive that "wins." Not hot water... I am not a plumber. Texas licensed for AC and heat only (HVAC). Yes essentially that is the "service" I offer as well as the part of the world I live in. Air conditioning and Furnace repair service in Katy, Texas area. When I say "service" I mean it. Every day, including summer holidays, weekends. Repairs also include equipment replacement. I myself install all new equipment I sell. I don't sub out work to sub contractors unless the contract specifies that (which is extremely rare situation). If you don't like the way I do things you're free to look elsewhere. I'm not here to tell you what your ears are aching to hear, I am here to tell you like it is. (Firmly and exponentially based on experience.) You don't have to like what I say, most of the time it's not pleasant due to a variety of reasons. In some aspects similar to the confrontational aspects of this forum boards conversations. Anyone who has viewed my posts know I come thick skinned. Disagreements do not phase me. If you want a gimmick, chase a gimmick. I could not offer the service I offer if my approach didn't work after all these years. I'd be running back around chasing my tail. You'd never get thru when you try to call me. Seriously? Think about it. Chest pounding: If you want to call it that it's your opinion. You're free to have it. My experience is my experience. 26 years. Easily verified. 13 years running my own company. Again easily verified facts. Essentially it's an advertisement. I am not paid to be here. I am here drinking my morning coffee filling in that time. If this isn't advertising my business what purpose would I have to be here? I don't come here to argue with the metamucil fan club that propetuates this board. Ha, ha... you know who you are. People search for me. All I have to do is leave bread crumbs so people can find me. AC repair service Katy, Texas area. Everyday. When I say something I mean it. Not a spam service. Don't sell your info. Don't pester you. You initiate the service you want. It's not that difficult when you know what you're doing. If you want a 20 something or 30 something coming to your home, you have to ask yourself how much experience does this guy really have? If that's what you want go for it. I've worked for companies like that... having to go back behind some newbie over and over and over. Used in not very fun ways. Follow my rules. I've been doing this longer than some of you have been alive. My methods work. Experience. What is it worth? Who else on this board in all the world listed as a pro HVAC service provider has my work ethic? Name one besides me. (beside the mini split warehouse spammer) Truth is stranger than fiction. There are people out there who read these threads and never post due to this kind of argumentative climate so frequent here. How could I know such a thing? I service the Katy, Texas area.