Calling all fellow Nerds: Heating and Cooling a low-load Multi Family?
Im in the early stages of planning a ultra low- load Multi Family Project in Zone 6A. Planning on a two story building with 8 units total, each between 550 and 600 interior, conditioned square feet (4900 square feet total). I did a rough heat loss calc and assumed a load of about 2,800 btus/hr at 99% Design Temp for each unit. I have not done a cooling load calc.
Heating these would be easy and cheap if I just used electric baseboard heat. But how would I cool the units in the hot but brief summers of western NH? Units will have Tilt and Turn windows and I would prefer not to have window ACs hanging out.
I thought about ductless mini splits but this seems expensive and I will have to come up with space to keep 8 condensing units outside. Also, even the smallest mini split would likely be over-sized. Multi-splits seem like a nightmare.
Would a ducted mini split work? I thought about having a Ducted 9k Fujitsu on each floor. But how would I regulate the thermostat across 4 units? What about the make up air? Can you run ducts through fire/party walls?
Finally, I thought about a Magic Box option as I will need ventilation as well (21 CFMs per unit). I’ve played with a CERV machine a couple of times and was really impressed. The Minotair V12 looks really neat too. This seems like the most expensive option though and would require two holes in the air barrier for each unit.
So, in summary, What would you do???
1. Option 1: Resistance Heat. But Air Conditioning??
2. Option 2: (2)Centralized Ducted heat pumps and (2) centralized HRVs.
3. Option 3: Magic box in each unit.
4. Option 4: Better ideas?
Hope to hit the PHIUS standard with this but low loads are creating some challenges!
Thank you all-
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