Originally Posted by Artco
hanging is probably more costly for sheetmetal install. you need real good vibration isolation if you hang it.
If you set it on the ceiling joist you can insulate below the aux pan. and set the unit in the pan.
if you have the height hanging is more comfortable to service.
I would figure it would be the opposite ( for vibrations ). I thought by getting it off the ceiling joists and hanging it off the roof trusses that it would cut down on any noise / vibration that might be heard through the living space.