Review mini-split setup
good afternoon folks,
I’m building a 2000 sqft bungalow with conditioned, semi finished basement. 9′ ceilings on both levelss, to a little below “pretty good house” standards. R70 attic, R30walls, R7 triple pane windows, R5 doors, R30 basement walls, and R16 subslab, aiming for excellent air tightness. Fully ducted ERV, ventless dryer, recirculating range hood, and the achillis heel, a wood burning fireplace, “sealed” combustion with outdoor air supply kit.
Heat load calcs came in at 22,000btu/hr for the whole house incl basement (-25*C outside, 22*C inside). Cooling load, incl latent came in at 26,500btu/hr (30*C outside, 24*C inside). The calcs are further broken down based on my “zoning”.
Kitchen/Living Dining: Heat 6800btu/hr, cool 12500Btu/hr : Going with a 12000 mitsu single head to come close cooling load (glazing kills me in this room in the summer, site is an open field right now, but intend on planting strategic trees for summertime shading, as i lost two 100′ tall giant ash trees to the asian beetle), I’ve got 3′ overhangs all the way around, but south-west is killer.
Master (incl ensuite and 2 closets): Heat 2900 btu/hr, Cool 4800Btu/hr: Going with a 6000 mitsu single head
Bedrooms + basement bath and basement bed: Heat:5800btu/hr, Cool 6100btu//hr: going with a 9000btu/hr ducted mini (all short runs, unit will hand from floor in basement)
Remainder of Basement: Heat: 6400btu/hr Cool 3300 btu/hr: going with a 6000btu/hr mitsu single head (large mechanical storage area can just get spilled from adjacent rooms heat)
Total capacity: 33,000btu/hr for both heat and cool, so i am about 1.6 times oversized for heating and 1.25 times oversized for coolingm, when i look at it from a whole house perspective.
The only place i think i could potentially reduce capacity would be in the living room, and go with a 9K unit, with the understanding that on the 10 super hot days of the year, when the sun is beaming in through the unshaded south-west facing windows, that the room will get to be warmer than the set point, and the unit will be running full tilt, there will also be spare capacity from the other units to help balance out the load. This doesn’t really bother me that much, as during the summer, i really only like it cool for sleeping, and will have a separate unit for the bedrooms.
Thanks for the review and advice.
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