Thanks all! It sounds like, on this forum, no one is worried about a ductless unit being able to supply these three bedrooms via ducts (that is what one salesperson was trying to tell me--he'd not ever use these with a duct run longer than 6 feet, and certainly not 3 duct runs...) In fact he said, the ductless system is "rated at only .2"w.c maximum. Typical duct systems are designed at a .5"w.c. static pressure, the low static units are best suited to having the air outlet directly against a sidewall and the air inlet directly below the unit,..." This is where it definitely goes above my understanding, but the salesperson trying to sell the ducted ductless system says they just size up the ducts so there isn't as much resistance on the interior head. I just wish there was a lot more information available (in English) on these systems and how they have been used well.

You definitely don't want to oversize the current equipment to compensate for a loft space, which by its nature will be hard to condition relative to the entire upstairs space. An oversized unit would make matters worse by running shorter cycles (less dehumidification and more importantly, less conditioning of the space that has a higher heat gain relative to the rest of the upstairs). First: Has a load calculation been done on the upstairs to determine the capacity needed for each room (including the loft)? Airflow balancing is likely in order to improve airflow to the room, which may require larger supply ducts. But you still may not be comfortable all the time. I'm assuming the thermostat is in the main hallway or master bedroom, nowhere near the loft. Zoning is not really an efficient or feasible option with that small of a space and that large of a single-stage system. You could try running the fan in the "on" position for air circulation. You could also install a thermostat with averaging capabilities to average the temp in various upstairs rooms, including the loft. I really like the mini-split option. Mitsubishi mini-splits are VERY nice, and I think this is a great application for one. The inverter systems are variable capacity, so the output will match the demand of the loft.

Hi ionized. Our issue with running actual ducts is that our house is very, very, very old and the original very, very, very old part of our house is solid one foot thick log walls. Going through them at any point is a nightmare for anything. We have a new addition, which would be fairly easy to run duct work, but working it into the old part of the house, which also has only 7' ceilings which are completely open ceilings with timber joists (bark still on them), which we plan on leaving open. We plan on adding some sort of insulation in the flooring between levels but between solid walls, no actual ceiling space and of course no basement, a "ductless" system is seeming the better way to go. Also, no we have no natural gas. Not knowing a whole lot, I would guess I need to run it into 6 rooms. 3 bedrooms, living room, dining room/entry, and kitchen. Right now our coal heat is actual a free standing base burner coal stove, so not central heat. Real turn of the century stuff, but believe it or not seriously efficient and the more insulated the house gets the less I think I need heat other than it, except for the fact I am living in the turn of the century stoking a coal fire daily. Because of the log wall set up the only room that is left out is our new MB. It is on the outside of the log house in the new addition and not on the same level as the stove. So the circulation just doesn't get there very well. There is also the more temperate times of year like Oct. when it would be nice not to be running the stove and have easy access to heat at night if it gets to 30 like it did the other night. My few real questions are do I need to have an additional heat source like baseboard heating for this type of unit? I saw a Youtube video that said if it gets too cold they don't run right. Would my coal stove be OK (we have no plans on getting rid of it and will continue to burn it in the coldest months of winter), or would I then have issues in my MB if I didn't get enough heat up there if the temp dropped? Aslo, I read somewhere and now I can't find where, that there were 35' maximums on the length you can run from the compressor outside. Is this true of all systems or did I read this on one site or someone talking about one manufacturer? If so I am thinking I need two compressors to service different areas of the house, is this how the cost starts adding up quickly? And do I need to hire a professional to install it? I promise we are not average DIYers. We would not be ready to install the entire system at once at any given time. I was hoping to educate myself, decide on a system, buy the parts we need as we go room to room. We are slowly working our way through the house, but we are probably looking at a 8 year total project.

I've made a lot of comments here about mini splits. See if you can pull them up with a search. Off the top of my head: Those rooms are awfully small to be putting a mini split in each one. Do you have heat load calculations? You might be better off with a small ducted unit stuck somewhere if you have room. Ducts are best installed in the living space. How high is the hallway ceiling; can you fur it down? From my limited experience, the 1:1 units are more efficient than the multi splits. There another characteristic that goes unnoticed in comparing multis to 1:1 equipment. Assume that your outdoor inverter units can throttle back to 10% total capacity. Assume that you have two 6000 BTU indoor units. The outdoor unit in a 1:1 situation will be able to throttle back to 600 BTU. In a multi situation, if you are running one indoor unit and assume that the outdoor unit is rated at 20,000 BTU, the minimum will be 10% of that or 2000 BTU. In the latter situation, the indoor unit will be snapping on and off a lot more than in the former. Another thing to keep your eye on is the functionality of your remotes. My Mitsubishi remotes will not do a true set-back, only on/off. I don't do much heating so it is not as big of a deal for me as it would be in Penna. I like to sleep cool and have the room warm when I get out of bed. In the factory programming the fan slows down as the set point is approached. In the heating mode, the high-wall-mounted units become ceiling heaters in my experience. It is kind of predictable given that the intake and supply are both up high. A higher, manually-set fan speed and a ceiling fan are both solutions this problem.