Heat & cool new PGH house w/ one mini split head & ERV?
We are half way through building a new high performance home in southeastern, CT – 5A. I call it a Pretty Good House +: 2,000sf 2 story, 10″ double stud walls with dense pack cellulose, triple pane Intus vinyl windows, simple shape, open 1st floor, high degree of air sealing and paying attention to the details. I have the manual J from our energy rater and I’m trying to finalize the HVAC design as we are ready for mechanical rough-in.
Manual J shows we need: Heating 11,000 btu 1st floor, 5,300 btu 2nd floor, Cooling 12,500 btu 1st floor, 7,000 btu 2nd floor. I’m an architect and willing to experiment a bit since this is my own house.
My safe design strategy includes a hyper heat head sized for the first floor load and a mini split ducted cassette on the 2nd floor with 2-3 very short runs supplying the bedrooms. A Recouperator ERV is also part of both designs. My 2nd design, somewhat more risky, includes one hyper heat head sized for the whole house and located on the 1st floor. I’m not concerned about heating during the winter due to warm air rising – 2nd floor should be okay. My concern is the south facing 2nd floor bedrooms not receiving AC during the summer. If I exhaust the first floor with ERV pickups close to the floor level to grab the cool air, and then supply the bedrooms on the 2nd floor with the tempered in coming fresh air – will it be enough to cool down the bedrooms a little?
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