In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
All my steam radiators suddenly filled with water
Today I noticed that ALL of my steam radiators were suddenly leaking water out of the air vents, apparently because the radiators were at least partly full of water. A few gallons leaked out of one. I saw that the water level was out of sight above the top of the sight glass on the boiler, so I opened the drain. At first a lot of pressurized air came out, and then 10 or 15 gallons, until I could see the water level in the glass. I should mention that in the past couple of weeks, there was LOUD hammering in the pipes occasionally, as if someone was hitting the pipe hard with a hammer.
A similar thing happened a couple of years ago - no leaking that time, but the water level was above the top of the sight glass. I drained out a couple of gallons until I could see the water level in the glass, and everything was fine (until now).
Whenever I add water to the boiler, I don't fill it excessively high - I can always see the level in the middle of the glass. So I'm wondering, how does the water get "stuck" in the pipes and radiators? Is it because a bubble of steam forms in the pipes that blocks the water from draining back to the boiler? How can I prevent it from happening again?