Does the air handler need to be vented outdoors when the installation is in a foam insulated sealed attic?

No. The ACiQ-24-AC-B / ACIQ-24-AHD air handler does not appear to require a separate outdoor vent simply because it is installed in a foam-insulated, sealed attic; the installation instructions instead address sealing and insulating the air handler itself when it is located in an unconditioned space, primarily to prevent condensation and heat transfer.

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