hot water radiator troubleshooting
My house was build in 1932 and has hot water radiator heat. I have bled the radiators that I can (on a couple of them, the fitting you open to bleed the radiators has been removed). A couple of questions:
Why would the fitting to bleed the radiators be removed?
Also having a problem with the two basement radiators. Basement is divided into two rooms. In the family room there are two radiators. I believe the system is called a one pipe system, that is one pipe goes across the top of the walls, and pipes come down to the radiators. When we first turned on heat, radiators in basement were warm and did not need bled. A few days ago the basement radiators stopped working. The pipe going across the top of the walls is still hot, and the top of the pipes coming down to the radiators is still hot. But the radiators are cold. We have had a couple of weeks of very cold weather here (western PA). Oh, and there is no air in the radiators, they are full of water. I've attached a photo in case that helps (our first winter in the house). The radiators have not been turned off and there has been no change in water pressure, as far as I know.
Any ideas? Many thanks.