Alright, I had been debating getting a ductless system for about two years now (lived in this house for over three) due to the heating issues I've had in the past. We live in a 2100 sq.ft split level that had baseboard and a woodstove in the closed off basement when we bought it. The first winter we owned the home, heating was futile. The woodstove in the basement couldn't due much since there was no direct access to the living area above, not to mention the fiberglass batting in the basement ceiling. The next winter, we removed the batting, and built a set of stairs into the basement from the kitchen above (picture taking a circular saw to your hardwood flooring). I also purchased an Englander NC-30 stove to replace the smoke dragon that we had. That made a HUGE difference, but we still needed to supplement upstairs with an Edenpure, that to me, wasn't very efficient and still couldn't keep the temps higher than about 66 on average. Our lowest living level was remodeled the year we bought it, and we built a stone fireplace with a Regency P90 propane fireplace. That heats the ~500sq.ft family room more than adequelty. It was out main floor (the kitchen/gym/living room) that was struggling to stay warm. So after much research, we went with a local Mitsubishi Diamond installer, and purchased a Mitsubishi MXZ-2B20NA with MSZ-GE09NA and MSZ-GE12NA evaporators. These were to service our ~900 sq. ft main floor. They were placed in the following locations: Here's a spec sheet copy from the unit showing guaranteed operating temps: We had the unit installed on October 10th which is about the start of our billing/metering cycle for our electric bill, so it was time great. We just received our bill the other day, and we're using WAY less electricity than this time last year even though there were two more days in the billing cycle compared to last year, and our average temps were 1 degree lower than last year. Take a look: My impressions? So far, it's doing a good job holding the room temp to about 70-72 depending on outdoor temps. It's quiet, it's efficient, and I'm happy overall. When the outdoor temps are in the mid 30s-40s, this thing keeps the house TOASTY. The problems? Well, for one, the unit temp as denoted on the thermometer is never accurate to the actual temps being put out by the unit. For instance, I placed a thermometer right next to the vent on the 12K unit which had the remote set to 74 degrees. The HIGHEST the temp reading on the thermometer was 72. Most of the time it's around 70-71. This discrepancy gets larger with colder temps. For instance, this morning, it was 27 degrees outside. I had the unit at 74 degrees. The thermometer read 70, and the T-stat in the room for the other heating system read 68! I have been in contact with the installer, and he told me to change the fan speed from auto to a pre-set constant speed like 2 on the 1-5 scale. That helped, but I also worry about the efficiency of this practice. It seems odd to me that for a unit rated down to -4, that it would be struggling so much in the mid-20s. Could there possibly be an underlying issue here? Maybe the system isn't fully charged? I've checked the outdoor unit for excessive pooling or signs or defrosting not working, but all looks well. Could the unit be undersized? Thoughts?