... to add AC only for a small 2 bedroom slab-on-grade home which has radiant in-floor heat. Upper Midwest, 1 mi. from a Great Lake. Main house is 890 SF: Living/Dining combined and Kitchen face east, Kitchen is on southeast corner; on the west side, the Bedrooms flank one Bath and central Hallway/Attic access. Utility room 130 SF is attached on south, access door from Kitchen is often closed. Garage attached on south side of Utility. Large east windows at Living and Dining and Utility. I understand load calculations need to be done abstractly, however seasonal canvas awnings limit solar gain on Living, Dining, and Kitchen. House is clad in stone, together with the concrete slab it tends to provide a stable environment. Attic insulation is original mineral wool plus 3 1/2" batt for total ~6", some additional batts around eaves; exterior walls 3 1/2" batts; windows mostly original single-pane with new wood storms. Attic storage space is important use. Corner lot, condensing unit must be on southwest corner of garage. Condensate drain line must go to laundry standpipe in Utility.
I am not seeking traditional system proposals, I've focused on Unico, I have three proposals, I'd appreciate comments before I seek some clarifications from some of the proposers, I'll identify them as $, $$, and $$$. I only have direct experience (positive) w/$$$, all three are mentioned as reputable by local Unico distributor. So ...
- Size unit: $ 1.5T; $$ 2.5T; $$$ 2.0T. (I have not yet asked $ to double-check his load calc; $$ states he had a Unico engineer double-check the load calc; $$$ recommended not including Utility outlet to keep unit from being 2.5T.)
- SEER: $ states 13; $$ did not note; $$$ states 13.
- Air handler placement: $ and $$ south end of Attic near Utility; $$$ central area of Attic.
- Return: $ Kitchen; $$ and $$$ central Hallway.
- # Supply outlets: $ 12; $$ 17; $$$ 14 ($$$ no outlets in Utility).
- Condensing unit: $ Carrier; $$ Amana; $$$ Armstrong.
- Supply plenum: $ and $$ Gustafson pre-insulated metal; $$$ "sheet metal w/ ext. ins."
Any comments on any of these details or additional thoughts are appreciated, thanks.