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What is this valve?

Well, cold weather is close.  Working on my old one pipe steam system again.  Found one radiator in small bathroom that surprised me by being piped like a two pipe system.  The inlet valve is at top of rad.  The return line has no trap.  It is dripped directly into a wet return.  I'm trying to move the return line so that it is hidden inside the wall.  The thing that is puzzling me is that on the old line there was what appeared to be a tee in the line.  When I got a closer look, it is something different.  Wish I could post a picture, but can't right now.  The top side of the tee has what looks like a cap that screws on.  Then there is a small plug that screws into the side of the tee.  The inside part of this plug appears to be a copper rod that  is about one inch long that seats in the opposite side of the tee.  When I tried to figure out what it is, the only thing that came to mind is that maybe it is some sort of vent that allows air to escape until steam hits it.  But I don't see any vent hole.  I've searched, but can't find anything like it.  Can anyone please interpret my lousy description and tell me what this is and whether it is necessary in the system?


  • Brad WhiteBrad White Member Posts: 2,393
    Sounds like

    a thermostatic radiator valve without the thermostatic head.

    Does it look like the attached (with the adjustable head removed)? Something like it, perhaps an older version? These valves have been around since the 1920's and 30's.

    And how are things at Mel Rowe's Place?

    Sorry, I can never resist saying that... :)

    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • mel rowemel rowe Member Posts: 324
    What is this part?

    Thanks Brad, but not one of those.  There is no apparent air vent of any kind on this rad.  As I said, it is piped like a two pipe system, but with no trap.  This part I am trying to understand, is at the bottom of the drip leg, is very much like an a regular tee, but has more of a cap on it, instead of a plug.  And then it has this very small plug in the side that has a small copper rod attached that is about one inch long and slots into an opening on the opposite side.  I almost think it is some kind of air vent but I cannot find any opening where the air would escape until the steam hit it and closed it off.  If it is only some kind of air bleed valve, then I don't know the purpose of the copper rod.  If it is not some kind of air vent, then how would steam ever push the air out?  But it has worked okay for years.
  • Brad WhiteBrad White Member Posts: 2,393
    Sorry, Mel

    I missed that you said the valve was on the return side, not the supply on the radiator.

    I have a friends with a similar 1880's-90's vapor system, two-pipe with express returns to the basement wet return and vents on the radiators. Works great but as you can see, all the air makes it out at the radiator and main vents.

    Does your radiator not have vents, at least this particular one?

    I know you said you could not yet post a photo, but I bet someone, likely in Baltimore but in other places too,  could tell you what that is. :)
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • mel rowemel rowe Member Posts: 324
    What is this part?

    There is no vent on the radiator.  That's why I was thinking that this part must be some kind of air vent, otherwise how could steam enter the rad?  Seems like a regular vent at top of rad would have been so much easier.  I've considered doing that but getting the plug out after 70 years doesn't seem likely.  I can't reuse this part because one of the attached nipples broke off when I was removing it.  So it looks like I need to figure out what it is and get a replacement.    
  • SteamheadSteamhead Member Posts: 13,815
    Sounds like

    some sort of expansion-type trap. If the radiator heats, the air has to be getting out of it, and if the air is getting out it is leaving at the return connection since the rad has no vent (assuming it doesn't have an In-Airid vent). Look for an air vent somewhere downstream of this unit. Did you find a name on it?

    Take some pics when you can. We'd love to see it.

    And welcome back, Brad!
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • mel rowemel rowe Member Posts: 324

    Well, I've gotten the plug out of the rad, so I can install a regular air vent.  Now I don't know of any reason to worry about what that part was and what it did.  I am curious though, so I still plan to try to post a picture.  Thanks for the interest and advice. 
  • mel rowemel rowe Member Posts: 324
    Picture of part in question

    Finally got a picture for everyone to have a look at.  I found another of this same part in the drip from a second rad piped the same way, like it is two pipe.   The only thing I can figure is that it is to be used as a way to clean out the drip leg.  But then why does it need the small plug?
  • mel rowemel rowe Member Posts: 324
    Any ideas, anyone?

    Still looking for any info on this part?  Thanks.
  • RodRod Posts: 2,067
    Picture Link is Bad

    Your picture link is bad
  • mel rowemel rowe Member Posts: 324
    No luck.

    Apparently that did not work either.  I give up.  Thanks anyway. 
  • mel rowemel rowe Member Posts: 324

    I went back and clicked on the first link and it worked for me.  Oh well.
This discussion has been closed.


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