Noisy Steam Radiator Help

AndyMidwest

I just moved into my home and I'm looking for some help to quiet a noisy steam radiator. During a heating cycle, there is an initial, brief hiss, followed by silence for about 2 minutes. Then, for about 15 minutes, the vent repeats a cycle over and over again where it moistly whines for 5 seconds, then a metallic click stops the whine (I assume the vent is closing) then it opens again and whines again, etc. It's quite loud.

Every other radiator in my place is quiet. Only this one makes the annoying noise. Unfortunately, it's in my bedroom.

Here are some details:

The home:
it's a 1920s 4-flat, 2 up and 2 down. I live in a lower unit. The boiler is underneath my unit.
The system:
Single-pipe steam. 15 year old boiler, steam traps replaced 2 years ago. Original iron pipes ranging mostly from 3x to 1 3/4 x size as they step down toward the radiators.
The radiator:
It's the last in its "line." It heats up hot and thoroughly. I have tried a brand new Hofman 40, Maid-o-Mist D and a Hoffman 1A vent. It currently has the Hoffman 1A. The Hoffman 1A clicks MUCH louder than the Maid-o-mist, but both produce essentially the same noise cycle. I have tried the Hoffman 1A adjusted to 6 (the fastest) and 1 (the slowest). The settings appear to have little to no effect on the noise. I repacked the valve, which looks old but appears to work fine.
The insulation:
Pretty terrible. The delivery line has asbestos insulation on about 1/5 of the pipe. The rest is uninsulated. I have ordered new insulation tubes and plan to install them this weekend. I won't touch the asbestos but will insulate everything that is not insulated now.

Thanks for any advice you can offer.

KC_Jones

AndyMidwest said:

steam traps replaced 2 years ago.

Ok need to clarify, if you have traps, that's 2 pipe steam, and there shouldn't be any vents on the radiators. So what traps are you talking about?

AndyMidwest

Thanks for the quick response, KC_Jones.

I am quite certain it's a 1 pipe system. A neighbor referred to "traps" on the condensate return lines, but may have gotten the term wrong. I am new to all this, myself. I am including a few pictures which should help at least clarify what I'm working with.

The (possibly misnamed) "trap"

The boiler system

The radiator

ethicalpaul

that's an odd pattern. I was going to suggest a MoM vent to avoid at least the "clank" but I see you already did. But you went back to the "clank" because... why?

Also a D is a massive size for a radiator. I wonder if the fast vent speed is letting steam get to the vent too quickly, which then closes it, but then the radiator still had air in it and that kept steam from coming in until the vent cooled and opened again...something like that.

Try the MoM again (to get rid of the clank) but this time with a more reasonable size like a 5 or 6

AndyMidwest

I went to a Hoffman because of the good reputation of the vent. Didn't know about the clank factor until it was installed. Now that I think of it, the Hoffman 40 didn't really have the extreme clank factor that the Hoffman 1A did.

I'll try the MoM 5 or 6 and see if that helps. I'm still stumped about why all of these vents have been so much louder than any other radiator in the place.

dabrakeman

Problem radiator I assume is 100% full of steam when it is making the alternating hiss and clanking noise but are the other radiators in the flat also 100% at that time (last column with the vent hot) or is this radiator getting steam much faster than the others?  If the one in your bedroom is heating faster is that your intent?  You may just not have the system balanced very well and need to vent this radiator slower given it is right above the boiler and maybe vent some of the others more quickly.  MoM 4 would be a good option if want to vent slowly and also not clank so much when the radiator does fill.

Probably better question at the moment is whether you really have functioning traps or if don't whether you have any main venting.

Does this happen every cycle of the boiler or are you experiencing it just on a recovery after a setback?

ethicalpaul

Problem radiator I assume is 100% full of steam when it is making the alternating hiss and clanking noise

May be...but honest question: how could the vent open and close repeatedly if the radiator were full of steam?

AndyMidwest

The repeated opening and closing of the vent occurs as the radiator is filling with steam. Once it is full of steam, the repeated noise stops.

The same delivery line first feeds 3 other radiators on its way to the noisy one, which is the last in line. I have noticed that the radiator right before the noisy one is still filling when the noisy one is beginning it click/whine cycle. But the noisy one continues the noise cycle as it fills after the previous radiator in line (bathroom) is full.

I actually don't care TOO much how quickly the noisy radiator fills, I just want it to fill more quietly.

ethicalpaul

OK then I would say put a nice slow #4 on it, either MoM or Gorton..those are both quiet.

After this last description, I'm sure the vent is closing and opening repeatedly because the steam is coming in too fast, traveling right to the vent rather than giving up its heat to the first sections of the radiator.

AndyMidwest

Thanks, ethicalpaul. Your explanation makes sense. I happen to have a MoM 5 on hand, so I popped that one in for tonight. But I'll pick up a #4 as well. Who knows, the insulation may help somewhat as well. I read somewhere that wet steam can sometimes exacerbate the speed to the vent problem.

ethicalpaul

Sounds good. Since you have the #5 just try that one before you buy anything. You might find it's a good speed for that radiator. And if you do want to slow it down more, you can just swap out the orifice on the top which is much easier than swapping out the vent.

AndyMidwest

Thanks again. I can't believe I never thought to simply swap out the orifice.