There are three floors in our house using the American Radiator. And so the pipe goes from the ground floor to the top floor. The noise is unbearable at night. It's constant clinking and clanking when the steam goes on. I'm trying to find a way to bleed the radiator ... if that's the case ... to stop the noise. Any ideas? Both the oil company and the plumber are clueless (I swear). I took a picture of the knob on, the knob off (is that the key?), and the only other gadget that looks like a knob on the right side. I haven't slept in a week!
From the terrible pictures you posted it appears to be a steam system and the banging could be that the air vents were painted is not allowing the cold air to escape and having steam hitting a cold pipe or a radiator will cause hammering
Also the handles are missing on the radiator supply valves which is not a good thing because steam valves are designed to be fully open or fully closed not act as a tempering device
You could also have back pitched steam lines again allowing live steam to hit a water pocket (residue) condensate
If this only happens at night it is most likely the pipes are cold and when the heat comes on the extreme differential will cause sounds like someone hitting the piping with a sledge hammer