Radiators - steam - vent at least once a year, or when you do work on or open the system.

Had a meeting tonight, and the guy said his office was cold, he had a ceramic heater in the front. 9 radiators on the first floor, and he's cold. I explained about venting and some other stuff. He said he would get around to it. I knew he never woulld, so a half hour later I had all the cold radiators vented until they were piping hot. He couldn't believe the difference, and we unplugged the ceramic heater.

Be careful when doing this, it's not something you can take the pressure vent off and go do something else. Ya gotta listen to when the steam is coming, plug it up when the whole radiator is hot. Take too much time, the rediator not leveled right, and you'll be faced with scalding hot water under pressure coming out. Do it right, and your heating will be more efficient, and save some $$ along the way.