The 8x20 does reduce after 4 (3 of which we are talking about) take-offs in 15' after it goes through a wide/long side 90 and imediatly into a 12" round. The 12" round has 1 take-off of it then reduces to a 10" round after 8'. The 10" round runs the length of the house (25') under its girders (tight!). The 10" round ultimately has 4 equally spaced take-offs and is capped. All metal branches have dampers and are masticed and insulated with a vapor barrier, then masticed again over the FSK tape. We have been through 9 gallons of mastic so far.
Everything is done working from the farthest point back toward the air handler which is what I am discussing here. Its been two solid weeks for two techs. The job is impecable and the techs have been great at putting up with abuse. Did I say this job is tight...everyone has worn out the toes in a pair of shoes, pants pocket and jacket elbows. Not to mention the square lumps to the head on the hour. I truly am happy with this job so far. But we are at a point where some experience needs to come into play to do it justice, and they are a little short on that it seems.
Gotta run will return shortly.