Parallel duct runs
Installing a Panasonic ERV
The exhaust air must be within insulated ductwork. However, the ducts must pass through a 2×8″ joist cavity to reach the point of exhaust (not movable).
Manual D and common sense give me a 6″ round duct for this. Obviously a 6″ insulated round duct doesn’t fit in a 2×8″ joist.
Ductulator suggests that at the design CFM, 3x 4″ ducts would be equivalent. Those would fit. Obviously I would have to account for the fittings to split from 6″ to 3×4″ and back again.
Is this a no-no? I couldn’t find information online.
Thank you in advance!
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