There was an episode of Ask This Old House a week or so ago where they installed a minisplit for a customer. It was a single-car garage that the customer wanted to use as a home office (it was insulated). I thought the installation was pretty simple: 1. Locate and put a mounting bracket on the inside wall for the inside unit using a couple of screws. 2. drill/cut a 3" hole through the wall and place a sleeve (supplied) inside. 3. Set the inside unit up on the wall. 4. Locate and place the outside unit on a pad (purchased) outside. 5. install the bottom half of a plastic channel (purchased) to hold the wiring and lineset to the side of the house. 6. run and connect the 4-wire electrical line between the two units (purchased). 7. run the power line from the outside unit to the main power panel. 8. run the lineset from the outside unit to the inside unit. Surround the lineset with (purchased) insulation. Snap the top part of the plastic channel in place over the lineset and wiring. 9. Connect the lineset at both ends using the proper flare fittings (supplied). connect a vacuum pump to the service port on the outside unit, pump down and check for / repair any leaks. (You'd need a pro to do this.) Connect the main power line. open the inlet/outlet valves for the refridgerant on the outside unit. (refridgerant is already supplied with the unit.) Turn it on and cool down. Enjoy a frosty beverage of choice. This looks a bit more complicated than it is. But if you're a DIY person, you can do a lot of it yourself. Then an AC guy can come and take care of the lineset and powerpanel stuff.

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.

OP, if you are still reading this, and manage to get the existing drain unplugged, I have some suggestions to keep it from clogging up again if you want to keep trying to use the existing drain to avoid tearing into your walls. Please note two things, however, if you can get to the other end of the pipe or tube in your walls, you stand a good chance of unplugging it. Also note that fixing and painting drywall is a relatively inexpensive process that might allow a more permanent fix by changing to hard pipe or a different flexible tubing type. Make sure that your unit has its drain running out to the same side that the opening in the wall is on. Most of them have the option of draining out either the right or left side, but I have seen them installed such that the condensate runs to one side of the appliance only to have the pigtail drainage tube pass all the way across the back to drain out the hole on the opposite side. Make sure the pigtail has as even a downward slope from the condensate tray into the wall as possible. There should be no upward slope anywhere because it will encourage water and crud accumulation. It should be fairly easy to remove the condensate tray completely for cleaning. (I feel like you are already mostly there if not past that point if you have removed the drain pigtail. Check YouTube for videos.) Use some condensate drain tablets to discourage microbial growth in the tray and the drain lines. Now they are marketing specific products for mini splits rather than having to cut down gel tab and whatnot products designed for larger ducted systems. Rectorseal ACTABS DMSS is one product and PurCool Green Mini Strips are another. Note that if you take the main cover off and remove the condensate tray you will probably have great access to the entire squirrel cage blower to clean that with a vacuum cleaner and great access to the coils that can then be cleaned with a foam cleaner if visible lint is caught on that. If no visible lint is in the coils, you can spray on a neutral to slightly alkaline pH coil cleaner like Nu Calgon Evap Pow’r -C. If you keep the crud out of the coils and blower tube, it will probably help keep the condensate drain system more clear and condensate flowing.

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.