Noisy vents on single-pipe radiators

Dale

Good luck being in a coop. but the system needs more and maybe alot more main vents or the ones on the system need to be replaced and perhaps the reason they failed fixed first.

Willis Boyce

Noisy vents on single-pipe radiators

Hello! I found this site while looking for information about a problem that we're having with our radiators. We just purchased a co-op with a single-pipe steam heat system. The heat came on a few days ago, and the vents (?) on the sides of the radiators are making an awful hissing noise. It's so loud that it wakes us up; we've turned the bedroom radiator off. (The vent on the vertical pipe in the bathroom also makes the same hissing noise.) I read the Q&A pages and grok that the system may not be adequately vented, but I wasn't sure if the vents mentioned in the Q&A are the vents on the sides of the radiators or something else. What should I tell my superintendent?

bb_3

tell the super

to go to Find a Professional and get a good steam expert to the building.

Matt Undy

Do they hiss hot steam or cold air? If its after the radiator get hot then the vent is bad and needs to be cleaned or repalced. If its cold air coming out of the vent then either there is not enough venting or some of the other vents are clogged/stuck closed.

Matt

Willis Boyce

It seems to be steam

Thanks for the response. The radiator gets plenty hot. There is no problem with the heat, just the noise. The hotter the radiator gets, the more the vent spews. Air is spewing out as opposed to being sucked in.

oil-2-4-6-gas

.

where are you located i do a lot of commercial --maybe yours too

Matt Undy

Replace the vent

That isn't air spewing out, its steam. The vents are bad. They are supposed to close with the heat from the steam.

Unscrew carefuly with hand pressure only, you can snap off the threads inside the radiator. Put your hand on the side of the cylindrical part and support the nipple where it goes into the radiator with your fingers so that you are rotating at the threaded part without pusing sideways.

Make sure the new vent is the same size as the old one. Use a little teflon tape on the threads. Pipe dope can cause problems with how the boiler steams if it gets into the system.

You can try soaking the vents in vinegar for a while to clean up the scale inside them but they are likely pretty old and should just be replaced.

The steam coming out of the radiator means the boiler is losing a lot of water so the level in it should be checked. Also, the oxygen disolved in all that new water will make the boiler corrode much faster. It would be best to bing in a professional to show somone how to keep the boiler at the right level and to make sure the safetly controls associated with maintaining a minimum water level and cuting the burner if it gets too low are functioning. Automatic feeders on steam boilers are there for safety, not to maintian the ideal water level.

BTW, the vent is there to allow air out of the system to let steam move into the radiator from the boiler. It should be lettting air our until steam reaches the radiator. When the boiler shuts off, the system cools and the steam condenses back into water, the vents let air back in to fill the space the steam took up. Air flows both ways through the air vent valves at different parts of the heating cycle.

There was a segment on ask this old house on steam systems, if you can find and watch a re-run of that, that should help you understand better.

Matt

Fred Harwood

vents

And don't forget to have someone check the pressure. One-pipe steam systems should operate well on less than one psi. If yours builds much more, get a professional to install a Vaporstat, and to check the total radiator EDR against the boiler rating. They should almost match.

martin architect

replacing vents

Thanks to everyone for a fascinating site and a great resource. I have similar issues with my coop apartment - the vertical pipe in one room (a substitute for a radiator I guess) has a "D" vent near the ceiling that spits. We are on the top floor of a 4 floor building. I want to replace the vent, but how can I do it if the threads are frozen/corroded without snapping it off and creating a huge problem?

Thanks.

Matt Undy

Could you post a picture? It would help us figure out if there is some fitting that could be removed and replaced if it were to break. Various types of extractors may also get the broken piece out. Have you tired to gently remove it? Perhaps soaking the threads in liquid wrench or a similar product? Be careful you don't get it into the system, it can cause the boiler to not steam properly. A torch may also do the trick.

It is probably a vent for the whole steam main.

Matt

martin architect

Matt, Thanks. Will do when I get home.
The vent is not broken off yet - I am just nervous about damaging it when I try to replace. I think it has been there for a while and there is corrosion visible around it (from spitting I assume). I know you are supposed to use only hand pressure but am not sure that alone will get it off.

Fred Harwood

spitting

Condensate running down all over the inside of the vertical pipe is getting into the D vent. This may not be a good spot for the vent. A better spot would be on the side of a horizontal fitting, where the condensate is on the bottom of the pipe and can't get into the vent. Look for a better spot, even just before the last rad on the vertical pipe.

martin architect

here is the D vent pic

Here is the situation below. Vent appears to be tapped right into the pipe. Running corrosion is visible. The pipe goes through the ceiling into the cockloft (we are the top floor). A plumber told me this was simply to support the vertical pipe, which has no radiators attached to it (in our apartment at least).

Matt Undy

So he could pipe it out with a couple nipples and an ell so that it is at the top of its own foot or so of vetrical pipe? Would that be sufficient to keep the the condensate out of it?

It looks like if that doesn't just unscrew you should have no problem taking it out with a scrwe/nipple extractor. You could also carefully cut a few slots in the inside of the nipple stuck in the riser with a small hacksaw blade being careful not to cut deep enough that you cut into the threads in the riser and take it out with a screwdriver and hammer.

Usually brass to steel connections don't freeze together, it is just a matter of griping and turning it without breaking the somewhat brittle brass off.

I was thinking of amsll angle vents. Maybe the heating pros can suggest good ways to grab that large round vent with a wrench.

Matt

Matt

Fred Harwood

Vertical pipe vent

One-eighth pipe is not good for a horizontal run. Ideally, you would need to cut in a full-size tee, then add a shoirt, full-size, horizontal stub, then simply add the vent to the end cap of the stub (or a Gorton #2 to an el on the stub). That way sufficient space would exist in the pipe to allow air to go in one direction and condensate in the other. You need a bit of space to separate them in action. That would stop the spitting, provided the vent is good.

Matt Undy

Couldn't he drill and tap the pipe for 1/2" instead of cuting in a full size T? Is there a valve that has more of a chember to seperate water? I'm trying to think through how the flow works on that small a secion, if maybe an eccentric reducer might work without changing the tap size... It isn't the same conditions as a steam main where this would undoubtedly cause hammering.

Perhpas insulation of the pipe above the vent would reduce condensation enough that the valve would be able to seperate the condensate.

I also wonder if it might just be a bad valve.

Does the valve spit air and water or only steam and water?

Matt

Dale

Top floor

Does the pipe end at the ceiling or go up into the attic. If it ends at the ceiling the other post is correct and that vent vents the entire main. Breaking off vents happens all the time and any pro or anyone who works with metal can retap them.

Fred Harwood

Not sure

Not sure that a 1/2 in tap and nipple will fit the pipe. Also, for venting pipe as opposed to radiators, 1/8 taps work poorly, simply because the air velocity drags water with it. A larger and horizontal pipe lets the air and water separate.

Willis Boyce

Thanks

Matt,

Thanks. This has all been very helpful.

I observed the vent more closely during a recent cycle. First, the vent emits cold air, without making much noise. After about five minutes, it starts to emit steam, accompanied by a spitting sound that gets louder as the cycle continues. That continues for another 10 minutes or so, I assume until the heating cycle ends.

I believe that the cold air coming from the vent is expected; it's being pushed out of the way by the steam that's coming from the basement. But based on what I've read here, the vent should shut off as soon as it detects steam, right?

I was able to unscrew the vents from both radiators without much effort, so I'll bring them by the hardware store and get replacements.

Thanks for all your help!

Willis