Multi/mini-split cassette buried under blown in insulation?
I am in the planning phase of a house renovation (San Francisco Bay Area, zone 3C) which includes a new HVAC system and am considering a multi-split system with ceiling cassettes and ducted units. The unconditioned attic insulation is blown in fiberglass on the attic floor. Although not as efficient, the ducted units may have to go into the attic due to space constraints. The ducting would also be buried under insulation. None of the manuals and online references I have found seem to specify whether ceiling cassettes or ducted units can be buried under blown in insulation. Can these units be buried under insulation? If not, is one solution to build an airtight cover out of rigid foam insulation with spray foam (e.g. Great Stuff) around the penetrations?