Most people do not understand to bleed air you have to add water, if you have water no need to add to that radiator.
In most cases you need 2 people. Now keep in mind you have to communicate with the person adding water. I use a screw driver or a pair of channel locks. We use them to tap on radiators when we want water or want them to stop adding.
Most of the time I tell the person with me to watch gauge on boiler and add no more than 20 pounds, in a 2 story house, if you have a 3rd floor you might have to add a little more than that, maybe 22 pounds, But keep in mind the boiler has a pressure relief valve set to dump water at 30 pounds, and water does expand and increase the pressure when heated.
As 1 person watches the gauge, the other person proceeds to bleed air, starting on the first floor and proceeding to second floor. When you get to last radiator to bleed, tap on radiator to let person adding water know you are on your last one. Have a signal set up say 2 taps to add 1 tap to stop.
On most boiler systems there is also a watts 9D (Backflow Prevention Device) This is located on the water fill line and should have a valve on both sides of it. These are for maintaining. This device could spill some water when you use water fill not to uncommon but not a lot of water. It will spill water where it says vent.
If you need any more advice you can e-mail me at dispatcherbob@espmetro.com
Keep in mind these are simple steps if you have any doubt call your local heating person and they should be more than happy to help you learn about your system.
