Hi guys, hope someone can help, I will try to be as thorough as possible.
I have added a second floor to my house, I have the main trunks in place. Due to the location of the furnace (duct work for basement and 1st floor are existing, I am changing the furnace to a larger one, all load calculations have been done and everything is sized properly) the way everything lines up the I can't really use a plenum take off but would have to use a reducer to go vertical out of the top. is this allowed? I have checked a few near me but they all have a main plenum box attached to the furnace with 2 plenum takeoffs tying into the horizontal ducwork. I am also going to install volume dampers for balancing if that makes a difference. plenum is 20x20 the vertical duct is 16x10