First, this website is an amazing source of information and I think I have felt out what, I think, might be the issue - but want to run it by everyone here as well.
My wife and I purchased a colonial from the 1890's last year and are becoming acquainted with the sounds and personality of our heating system (single pipe steam).
Last night I was awoken to what sounded like surging water through the pipes that supply heat to that radiator. I immediately jumped up expecting my floor to be a wave pool, but no, no water anywhere, and the radiator was functioning (hot) but just a very loud surging sound. Now we are quite used to the sound that steam heat generates - but this seemed out of character. This radiator is on the longest run in the house and in an extension that was added in 2011 or so. I am sure this was not part of the original systems design. The radiator is pitched slightly towards the supply thanks to the help of some loose change under the feet. This is the troublesome
radiator in the house: the only one with any water hammer (very lightly when steam starts and turns off).
Full disclosure I did replace the air vent on this radiator around 2 months ago as it was not fully heating and the room was significantly cooler than the remainder of the house. The vent was rusty and I cleaned the area surrounding it before in stalling a new vent. Don't scoff, but we used a home depot - cheap vent when we did it as we were testing a theory - and should likely replace that vent at some point. This has helped, but the room is still not as warm as the rest of the house, but I digress.
I am wondering if the new vent is venting too fast, and it is causing an issue with fresh steam condensing too quickly and making noise. I know, I know, vent the mains fast and the radiators slow. The vent is adjustable, so I am thinking of turning it down a tad and seeing if we get this issue still. Eventually I would like some advice on a replacement vent choice and size - but I will need to provide much more information for those recommendations I am sure.
Below is a video that I took right before I got up - so it is pitch black - but if you turn the sound up you will hear the noise. Bear in mind that is about 5 feet away from the radiator in question, to clue you into how loud it was. Don't mind my wife telling me to go down and turn the heat off at the end
Thank you in advance for any insight!