How do you fix a banging, clanging steam radiator?

Answer 1

The most normal cause of banging is trapped water not able to drain down to the boiler.
That banging usually indicates that there is water trapped in the radiator that the steam is trying to push out of the way to get in (one-pipe radiators send steam up and water down that pipe near the shut off valve). Look at how level the radiator is. The end furthest from the shutoff valve should be raised a little higher than the valve end. Tap a wood wedge under the feet on that far side to raise it and let the draining go on.

Answer 2

There's air in the lines and the steam has to expand which causes the banging. Bleeding the lines will help decrease the noise. A Sioux Chief Mini-Rester Hammer Arrester can help prevent the hammering at each radiator.

Answer 3

it's been a long long time sinse i lived in a house with a radiator. from what i remember, they have a key that you can use to open a valve at the top to let any air out. then you turn a valve somewhere on the bottom to fill the air space with more water. then you need to check your boiler to make sure the water level in it is correct.