I managed to complete the installation of our Zehnder ERV in the River House today. In total, the system has six 8″ trunks; two for the outside intake and exhaust (which must be insulated and appear at the back of the unit, two for the west wing supply and extract (going through the wall), and two for the east wing supply and extract (up into the joist bays). Insulating the outside intake and exhaust ducts took 4 times as long as all the remaining work and was my least favorite part of the job. The whole thing looks a little like an octopus but I am pleased that I kept the ductwork confined to the footprint of the ERV so as not to encroach on the rest of the mechanical room.