Just got my first job helping a guy get a steam system (1 pipe) at one of his rentals (2 fm) in order. From talking to him on the phone I was able to diagnose most of his problems and tell him what needed to be done before I even saw it. Something several plumbers were clueless to fix.
Thanks to the expertise of this site BTW.
My Q is sizing the new vents for certain rads all of which are on the second and third floor. In some cases a 2nd floor rad is fed from a pipe that keeps going up to a third floor rad directly above. Would you use a vent the next size up for the 3rd floor?
I will post pics of the project in a few days.
There are a couple venting strategys explained in detail inside the handbook. Basicly you want to vent the mains fast and the radiators slow. Start with the mains and figure out how many cubic feet of air is inside them. Then figure how much air is inside each radiator. The mains should be vented using the 1 ounce scale, the radiators vented using the 3 ounce scale, and the risers "if nescesary" using the 2 ounce scale.
Re your stacked radiators. Just vent them normally, based upon how much air is in the rads. If they give you any trouble just vent the riser.