Minisplit retrofit in Climate Zone 2
I’m trying to figure out how to use a minisplit system on a retrofit project. I got a quote from an HVAC company (recommended by the equipment rep), but some of their opinions don’t make sense…which brings me here today.
The HVAC company proposed 4 zones with a 3 Ton compressor outside:
1 ducted 9k unit in attic, serving Guest Bath, Guest Bed, and Office
1 ducted 9k unit in attic serving Master Bed and Bath
1 9k ductless serving kitchen
1 9k ductless serving living
I don’t like the idea of putting units in the attic. That may be the only option for Zone 3, but not sure about Zone 1. I’m also concerned about sizing. Seems like there’s less room for error with mini splits.
1. How difficult is it to mount a ducted minisplit on a ceiling and run ducts through interior walls?
2. Could 1 ductless unit condition the Master Bed and Bath?
3. There is a 40 sq ft opening between the Living Room and Kitchen. Could one 15k ductless distribute air widely enough to condition both rooms?
4. As you see from the load calcs (below), some rooms have a big difference between cooling and heating loads. If I size for the cooling load (due to climate zone), some rooms won’t keep up with heating demand in the winter. If I size to the heating load, some rooms will be significantly oversized in the cooling season. Thoughts?
Below are the load calcs, performed by a third party .
(Room – heating load, cooling load)
Ma Bath – 2788, 887
Ma Bed – 5200, 2928
Total – 7988, 3815
Zone 2 (if I can use one ductless for both rooms)
Kitchen – 4250, 7231
Living – 5214, 4764
Total – 9464, 11995
Guest Bed – 4034, 2639
Guest Bath – 1314, 997
Office – 4430, 2752
Total – 9778, 6388
Whole House – 27230, 22197
Latent Cooling – 4879
GBA Detail Library
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