Opinion on Mitsubishi MLZ ceiling cassette series
I am planning to build a new house in Indianapolis, IN (Climate zone 5) and would like your opinions on using the Mitsubishi MLZ ductless mini-split series for heating and cooling.
My design consists of a 20’x60′ rectangle with the kitchen, dining, and living room as one long linear room with a mud room and powder room on the other side of the staircase, 10′ high ceilings. Upstairs there are 2 bedrooms, a full bath, and a master suite with bathroom, 8′ high ceilings. There is also a 12’x26′ wing with an office, bedroom, and a full bath, 10′ ceilings, connected by an 8’x6′ gallery.
I am shooting for a wall assembly around the R30 range. Do you think the MLZ mini-split series is a good choice for this project or do you think another HVAC system would work better?
P.S. Do you need an HRV with a mini-split system or just exhaust fans?
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Replies
>"I am shooting for a wall assembly around the R30 range. Do you think the MLZ mini-split series is a good choice for this project or do you think another HVAC system would work better?"
The whole house heating and cooling load would be the first step in making that assessment. Wall-R and floor area isn't a good enough metric to even start.
>"Do you need an HRV with a mini-split system or just exhaust fans?"
To make an R30 wall worthwhile calls for an air tightness level that would't really cut it with exhaust-only ventilation. Balanced ventilation is the best way to know that you're delivering the air where it's needed, and that it's coming via a clean path, not being sucked up from cracks in the basement slab or something.
Currently the MLZ cassettes don't come in individual mini-splits with cold-climate compressors. MXZ ... NAHZ compressors will work efficiently at zone 5 temps, but may be sub-optimally oversized for a high-R/low-load house.
Ergo, run the heating and cooling load numbers has to happen before picking the solution.