Radiator bleeding should take place once a year, when a system is started up in the fall.  Sometimes there will be no air in the radiators, but sometimes there is.  Mechanical contractors doing the annual maintenance on the boiler will often include this bleeding component in their service, and should check for air in all radiators in your system.  Air can also get into the radiators if work has been done on the system that involved draining and refilling it. Air can get trapped in a rad, not allowing the radiator to fill completely with water, leaving the radiator cool or cold.  Sometimes clients contact us thinking their radiator is in need of replacement, when all that is needed is to release the air using the bleeder valve.  One caution – please be careful when trying to bleed your own rads. Here’s a story from one of our technicians  at Ironworks Radiators Inc:

“I had a customer a few years ago, who decided to bleed her rads one night. She  went to do that, and lost a piece of the bleeder of her bathroom radiator.  She put her finger over the bleeder to stop to flow of the water, but she couldn’t leave, or the house would flood. So, she phoned from the bathroom, and said, “I lost my bleeder, I’m here with my finger over it, can you come by to fix it”?  I was actually very close by, it was about 11’o clock at night.  I went there and  put a new bleeder on the radiator! She had her phone with her, it worked out. She had the smarts to call…”