Hi all.  We are building a “multi-generational” home for the brood here in Massachusetts.  HERS rater shows 70,000 BTUs for heating load with my intended Insulation, windows, etc.  Manual J from my own access to free software and results from a few installers shows roughly 90,000.  I will be using Mitsubishi Mini-Splits and will expand into Attic and Basement as Family continues to grow, and those numbers above are reflective of end state full usage. 

From installer, three MXZ-5cNAHZ vs two MXZ-8cNaHZ are about the same install cost with the various zones/heads we’ll have at an end state.  He says since they are variable motors, it should be a wash from an electricity usage.  When I look at the submittals per unit at the different design temperatures, its difficult for me to be confident. Is it likely that there is a minimum electrical load drawing power even in mild days that would make 2 larger units better than 3 smaller units?  I’m seeing a 24000 minimum BTU for the 5c and 27000 BTU for the 8c at 47F.

Summary of Watts listed on the Submittals are below along with efficiency stats per unit:

Thanks in advance for advice.  Definitely learned a lot in last month or so, but still a novice.  Your help is always appreciated.