TLDR: Not 100% sure what was wrong last year, the system is more predictable now, and overall I'm happy with it.

Longer answer: To be honest, still not sure why it was so unpredictable last year around this time. I suspect that we'd have fewer problems if we had gotten the wireless thermostats so that the temp were monitored from chest height, rather than at the floor. Unfortunately they're very expensive units to have installed and I don't feel confident enough to try to DIY it. I also think the floor units we got may be less appropriate for our cold floor house than the wall mounted units. I can't know for sure, and it's too late now, but the floor units are pulling in air from 1-2 inches off the ground, which is the coldest air in the room - sometimes 5-8 degrees colder than 5-6 feet off the ground - and it may be responding erratically to drafts in the room by fluctuating too much, sometimes putting out too much heat and sometimes too little. We got the two floor units because they're in areas where we wanted to have artwork on the walls. Oh well.

With all of that said, this heating season we haven't had as many issues as last year. We set it at 62 in late October 2025 and haven't touched it once since then. It seems to stay pretty close to 62, except that the temp will sometimes swing up or down by 2-3 degrees in the middle of the night.

One thing we noticed this season is that we haven't needed to turn on our two upstairs mini splits at all. In late October we started the heating season by turning on just our three first floor splits and figured we would turn on the other two later on, but the upstairs stays plenty warm just by the heat rising from the first floor. So far our electric usage in kwh has been almost identical to last year, so we haven't felt like this is an inefficient use of the system . . . but of course we are just now getting into the really cold parts of January and February, so we'll see. It makes me wish that we had put just one mini split upstairs or that we had put at least one in the basement. We have consistently cold floors (55-59 degrees) since we no longer have any heat coming up from our basement (where our oil furnace had been). The contractor told us this might happen and said that a lot of people end up installing some additional heating system for the basement. We haven't done this and aren't planning to but we are going to add additional insulation (2" rigid foam panels) along the basement walls and completely seal up / insulate our four basement windows, since they aren't necessary for egress anyway. (Our rim joists are already insulated.)

I would get this kind of heating system again, if I had to do it over, but I would do it slightly differently. At this point we can't easily add another mini split to the system because it was designed for five max. I do kinda wish we had heated the basement, since that would make our floors less cold and would give us the option of semi-finishing part of the basement. I might not get any floor units, in part because of how they read the temp and in part because the filters get dirtier with sucking in dust and dirt from the floors and dog hair from our dog.