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Steam Heat Baseboard Radiator Spewing Steam

dcpalmerdcpalmer Member Posts: 6
I did a quick search and didn't see anything directly on point -- forgive me if I missed it. The few posts that seemed relevant were over my head! Bottom line: When the heat came on this AM, there was steam coming out of both ends of this vent (see pic), which has holes on both sides. It was like a humidifier in the bathroom. That's not supposed to happen is it? Should I just replace the piece? What's it called?

Relevant history: You can see that dirty water has also spilled out of this. I had a neighbor putting water in the boiler while I was on vacation. He put too much (because the water guage wasn't working proporlty). Perhaps that has gunked up the works.

Any advice much appreciated. In case you can't tell, I'm no pro! Just a homeowner.

Thanks so much.



  • JUGHNEJUGHNE Member Posts: 6,924
    If your sight glass is gunked up, what would your low water safety cut off be like?
    And you have to continually add water you might have a leak somewhere.

    You need a steam pro to check out your entire system.
    How about pictures of your boiler and piping near it?
    Where are you located?
  • dcpalmerdcpalmer Member Posts: 6
    Sight glass is fine and sensor no longer gunked. Had it dealt with. I'm guessing I have to fill up a bit more than usual (but it's not bad) in part b/c of this one radiator...but I could be wrong. The boiler and everything near it is fine and relatively new. I think the only issue is the steam blowing out at this one radiator part. I'm trying to get advice so I can replace the part myself if that's possible.
  • JUGHNEJUGHNE Member Posts: 6,924
    Then it looks like you just need a radiator air vent......assuming this is a one pipe steam convector.
    Maybe a Hoffman # 41 part number 401455.
    It is described as a convector vent, non adjustable port 1/8" bottom connection. This is a straight vent, not the 90 ell design that is most common. It might be too tall for your cover.

    Someone here may have a better suggestion.

    If you are into DIY steam maintenance then there are some good homeowner books available. "We Got Steam Heat!" is a good starter. Then "The Lost Art of Steam Heating".
    Both are a great read.
  • the_donutthe_donut Member Posts: 374
    You shouldn’t have to fill at all. It’s hard to see from this angle. Does it drop down in a 90 to through the floor? Looks like a valve with handle missing or a bleeder.
  • dcpalmerdcpalmer Member Posts: 6
    Thank you! Much appreciated. Any thoughts from others?

    And: If it were up to me, I wouldn't really be in to DIY...but the price of professional help (however fair!) is inspiring. DIY is actually fun when you figure it out...ONCE you figure it out.
  • JUGHNEJUGHNE Member Posts: 6,924
    There was a posting recently, maybe within the last 30 days, with a picture of a similar air vent.
    I believe that was a water or steam air vent that closed by hydroscopic means when wet/damp. They may not have been long lived for either purpose.
    Someone come up with a small steam air vent to replace it with if something like the Hoffman would not fit.

    The books mentioned, are themselves inspiring and would make DIY fun and interesting.
  • dcpalmerdcpalmer Member Posts: 6
    @the_donut - I'll take some more pics this weekend and post. From what I remember, that's on the end of a single pipe...the other end is the side that comes out of the floor.
  • dcpalmerdcpalmer Member Posts: 6
    @the_donut and anyone else:

    More pics below. I can now confirm that the place that steam is coming from is the end of the single pipe, not where the pipe comes up through the floor, which is on the opposite end. You'll now see in one of the pics below. I also took one pic -- a little hard to see behind the cover -- of the other end, in case useful. In the close up of the piece I initially wrote about, you can see a small hole...that is where the steam is coming from. And there is a small hold on the other side, too, where steam also comes out (180 degrees from each other).

    My central questions: Should steam be coming out of there? I know for a normal radiator the answer is no, so I'm assuming no. If not, then, should I just replace that end piece? Then, if the answer to that is yes, what is the piece? THANK YOU!

  • Danny ScullyDanny Scully Member Posts: 1,226
    edited March 2018
    @dcpalmer, baseboard and 1-pipe steam aren’t friends, and they never will be. Baseboard isn’t designed for a 1-pipe steam system, and this is often the result. Realistically, the runout to 1-pipe steam baseboard should be upsized, and the pitch needed wouldn’t be able to be contained within the baseboard cover. Having said all that, you can try installing a new vent, possibly a straight Gorton #4.
  • the_donutthe_donut Member Posts: 374
    Is this on the first floor or second floor? Does the house have a mix of radiators? I am wondering if there is a hot water zone in your steam system. Need to see attached piping to be sure.

    That fitting looks like an air bleeder for hot water. That pipe looks large enough for gravity water, hard to tell and steam pros will chime in.

    If the other radiators on that line are supposed to be steam, then replace the bleeder with a slow air vent if you want heat out of that unit. If it is a water, the bleeder needs to be closed. Use gas leak detector or soapy water to figure out if the bleeder or the bushings are leaking and tighten the loose fitting.

    Steam and water should never leave a properly working system. You should never have to fill the system.
  • Danny ScullyDanny Scully Member Posts: 1,226
    This is steam, not hot water @the_donut
  • nicholas bonham-carternicholas bonham-carter Member Posts: 8,133
    That vent looks to be wrong for the application. It may have been chosen just to put on something called a “vent” which would fit under the cover.
    The elbow at the end may have to be replaced with a reducer with the correct sized tapping for a real steam vent, So the cover will clear it.—NBC
  • JUGHNEJUGHNE Member Posts: 6,924
    Page 3 of Strictly Steam category, 2-6-18.
    "Steam BB vent maint help"

    This is discussed.....Hoffman #500 or #508.....MOM??
  • JohnNYJohnNY Member Posts: 2,443
    Yeah. What Danny said. Get rid of the baseboard. It's not compatible with 1-pipe steam. Changing the air vent isn't going to solve the problem.
    For troubleshooting and private consulting services, find John "JohnNY" Cataneo here at :
    "72°F Mechanical, LLC"
    Or email John at [email protected]
    John is the Boilers and Hydronic Heating Systems Course Instructor at NYC's Mechanics Institute, a professional Master Plumber, licensed by The Department of Buildings of The City of New York, and works extensively in NYC while consulting for clients in and out of state.
    John also oversees mechanical installations and maintenance for metro-area clients with his family's company, Gateway Plumbing and Heating along with his brother/business partner.
  • dcpalmerdcpalmer Member Posts: 6
    Thanks @Danny Scully and @JohnNY -- disappointing to hear. I had no idea. That's what was there when we bought the house...both the first floor bathroom and this second floor bathroom (@the_donut) right above it. Yes, all steam. I did find two old radiators in the garage. I wonder if they were removed from these bathrooms. Will try the Gorton and perhaps hire a pro.

    Thanks all. Much appreciated. Over and out.
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