Central air heat pump: sizing via kBTU/hr vs CFM?
My Manual J output for a ducted heat pump in the Seattle, WA area (climate zone 4 coastal) indicates 27 kBTU/hr heating load with CFM needs of 1001 CFM, and I’m confused by how to meet what seems to be an atypically large CFM-to-kBTU ratio. Is it a bad idea to get an air handler below this 1001 CFM value?
With fantastic advice from folks on another thread, it seems the best Mitsubishi option for me is ~3ton (32 kBTU rated) unit — the next lowest option (2.4 ton I think) would make me nervous as it’s rated at 26 kBTU/hr, which is 1kBTU below my Manual J based needs. Even with this larger ~3 ton unit, the air handler model (PVA A30AA7) that’s supposed to go with it maxes out at 845 CFM according to its spec sheet. What should I do here? Go another step up on the ODU? Mix an oversized IDU with the 3 ton ODU? Ignore it because I’m misinterpreting stats?
Air handler for 2.5-ton cc ODU, “air flow rate, dry” = 613-744-875 CFM: http://mylinkdrive.com/viewPdf?srcUrl=http://s3.amazonaws.com/enter.mehvac.com/DAMRoot/Original/10009%5CM_SUBMITTAL_PVA-A24AA7_PUZ-HA24NHA-en.pdf
Air handler for 3-ton cc ODU, “air flow rate, dry” = 613-744-875 CFM: http://mylinkdrive.com/viewPdf?srcUrl=http://s3.amazonaws.com/enter.mehvac.com/DAMRoot/Original/10006%5CM_SUBMITTAL_PVA-A30AA7_PUZ-HA30NKA_en.pdf
Air handler for ~ 3.5 ton cc ODU, “air flow rate, dry” = 788–956–1,125 CFM: http://mylinkdrive.com/viewPdf?srcUrl=http://s3.amazonaws.com/enter.mehvac.com/DAMRoot/Original/10006%5CM_SUBMITTAL_PVA-A36AA7_PUZ-HA36NKA_en.pdf
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