I may replace my current oil, baseboard boiler but would prefer bleeding the system at the boiler site (if it's possible) vs at every room separately. Is it possible to bleed air out at the boiler, without doing so at every baseboard? If so, what should I ask for when I talk to a potential installer?
To answer your question, you can have the installer install a purge/drain valve assembly.I installed this type purge many times. It will remove most of the air from a finned tube baseboard heating systems, but cannot be used on any other type of radiation. He installs 2 ball valves in series on the return line with a drain valve in between the ball valves. You hook a short garden hose to the drain and close one ball valve, then you open the drain valve and push the water and air thru the system to the drain expelling the air. You alternate opening and closing each ball valve to push the water one way then the other expelling the air. You may still have to vent a small fraction of the air at the vents on the baseboard radiation. Ask the installer if he knows how to install this system.