Steam hammer?

janeo213

I live in an old apartment building, on top of the boiler room, in the Northeast. Lately my radiator (photo attached, I have no idea what kind of radiator it is) had been making a fog horn sound and waking me up in the middle of the night. Since the boiler downstairs keeps my apartment hot regardless of whether the heater is on, the super showed me how to turn off the radiator. Soon after that, I started hearing a banging/rattling [hard to describe, sounds kind of rusty. I think it's from the pipes rather than the radiator.] Today, they replaced the valve on my radiator, and told me to always keep it on, because apparently turning it off caused the rattling. I asked them why that is, but they didn't give a very clear answer. Is there any reasoning behind this? I ask because I haven't slept well in a week and have an exam coming up; if their explanation doesn't make sense and there will be noises tonight, I'd rather go stay at a friend's and deal with this next week. Thank you!

Jamie Hall

If this is one pipe steam -- and I would imagine it might well be -- then turning off the valve will trap water at the valve, since those valves almost never turn off completely. The trapped water will happily gurgle and burble and bang and generally make a nuisance of itself.

You can tell if it is one pipe or two pipe -- if it's one pipe, there is only one pipe coming into the radiator (not very original name, eh, but there it is). There will also be a vent on the radiator somewhere -- usually about half way up the other end. Can you take a photo of the whole radiator, or at least both ends, and any pipes coming into it? Then we can help you more.

ChrisJ

Can you take a picture of the valve they replaced?
If it's a single pipe system with an air vent you can flip the air vent upside down while the system is cool and the radiator won't heat anymore or bang.

BobC

That might be convector, does that cover come off? If it does what kind or air vent is on it?

If the noise has stopped you could just block up the holes in that cover, that reduce the heat output significantly.

Bob

janeo213

Thanks for the responses! This is the inside; the bright silver thing is the valve they just replaced. Right now it's making a loud hissing sound, which I've never heard until today. They told me it's normal -- it doesn't sound very normal, but I guess I'll be able to live with it as long as it doesn't bang!

janeo213

Also, this is built into the wall, and there's a cover on the outside. Sorry if I wasn't clear; I really know nothing about this!

Jamie Hall

That is the vent. If you take that and turn it upside down, that should reduce the heat output a lot -- and, possibly, stop the hiss. Careful -- it may be hot.

ChrisJ

Make sure the system is off when you flip the vent.
If you do it while there's steam in the radiator it may never stop heating.

Fred

That may be a straight vent and may not be able to turn it upside down.

BobC

It looks like a cheap Home Depot Durst vent. They are supposed to be adjustable but really are not.

Either replace it with a Hoffman 40 or, if you really don't need the radiator to ever heat, replace it with a 1/8" brass threaded plug.

Bob

ChrisJ

Fred said:

That may be a straight vent and may not be able to turn it upside down.

Take it out and replace it with a 1/8" NPT plug.

Abracadabra

Could just use duct tape to seal the orfice From another use for duct tape that I think @Dan Holohan mentioned one time

janeo213

Thanks for all the suggestions! I'm so grateful for all of your knowledge and patience. I don't think I can flip it upside down because it seems to be built into the wall. There are two things I can adjust [the vent, and a knob that turns the radiator on/off]. For the last couple days, I turned both completely off, and that's apparently what caused the banging pipes. Would a plug solve both the hissing and banging problems? Or would a higher-quality vent be better?

Fred

A Plug will prevent that convector from heating at all, if that is what you want to do? You can buy a Hoffman #41 straight vent that usually works well to deliver steam slowly to the convector if you want it to heat. The valve (on the pipe that feeds the steam needs to remain fully open as it probably doesn't close fully and allows water to build up in the convector and steam to leak in causing the banging/noise.

Fred

BTW, Make sure that radiator is tilted slightly back towards the pipe that has the shut-off valve on it. If it is level or pitched towards the vent, it could be a source for some of the noise you hear. It you need to tilt it, put a couple shims (checkers or quartersor wood shims will work) under the feet on the vent end to tilt it towards the pipe.