One Multi- or Two Single Mitsubishi heat pump outdoor units
I’ve been reading the plethora of articles on the mini-splits and I’m going to go with this system for my whole house remodel. It’s a nice rectangle-shaped two story beach house (Newburyport MA) and I did go a bit crazy with a lot of windows and sliders. But lots of closed cell foam should keep the house pretty air tight and warm (a lot better than it was). Since the first floor is an open plan, I was thinking of a 15K BTU floor unit downstairs and a 9K BTU upstairs hallway unit. I do like the combined multi-zone unit for 24K BTU outdoor unit (such as the MXZ-3C24NAHZ2). I’m working on my own manual J using Load-Calc.net but I’ll admit I’m probably making a lot of mistakes as I putz with it.
I read on this site that the inefficiency in these combos can be pretty high. Should I consider 2 outdoor units instead? I’m assuming the upstairs unit is mainly for cooling and the downstairs for heating. I can’t really put ceiling fans upstairs so I hope the hallway unit or the sea breeze will keep it cool in July.
Thoughts on the one or two outdoor units?
BTW my general contractor loves the ducted air handler system but I hate the whole concept of ducting so I’m ignoring his ideas!