Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

1-way Steam radiator leaking

branimal Member Posts: 210
I hooked up a steam radiator and heard air coming out of the valve to radiator connection area. I put my hand there and felt air coming out. A few moments later water is dripping out.

The valve nut is on snug all the way. It's not cross threaded.

I've attached some pics below. The pencil is pointing to the general area that I think the leak is coming from.

Any ideas on how to proceed? Should I pressure test it?


  • KC_Jones
    KC_Jones Member Posts: 5,736
    Is it leaking on the radiator side of the pencil, or the valve side of the pencil?
    Is that a new valve?
    Is that the original spud for the radiator?

    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • Jamie Hall
    Jamie Hall Member Posts: 23,272
    What you are pointing to is the union nut joining the spud (the part threaded into the radiator) with the valve.

    Spuds are matched to their valves. Sometimes you get lucky and a spud from a different valve will seal properly when made up. Most often, particularly if the spud was not from the same make and era of valve, they won't.

    If we assume that the spud in question does match with the valve, it is important to remember that this is a union, not a threaded joint. The seal is between the two machined faces -- one on the spud and one on the valve. To get it to seal properly, those faces must be perfectly clean and smooth -- no nicks or scratches. Then you need to get the two pieces lined up -- side to side, up and down, and in a straight line. Push the two pieces together. Then you can tighten the nut, but not too much -- Hand tight and perhaps a half turn with a wrench should be ample.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • AdmiralYoda
    AdmiralYoda Member Posts: 627
    edited January 2022
    branimal said:

    I hooked up a steam radiator and heard air coming out of the valve to radiator connection area. I put my hand there and felt air coming out.

    Is this radiator "new" to this location? What I'm getting at was......was this radiator originally connected to that radiator valve in the picture?

    Radiator valves have a very tightly toleranced surface that a matching spud mates to. The spud goes inside the radiator. If it is some random radiator that wasn't installed with that valve, the surfaces will never match each other and it will leak steam.

  • branimal
    branimal Member Posts: 210
    edited January 2022
    The steam valve is new. The spud is old. I did notice it wasn't really a great fit when I was putting it on, but I just went about tightening it up. (Good tip on hand tight then half a turn with the wrench). Even after tightening it up radiator and vent connection still had a little swivel to it. The play was the spud not mating with the valve.

    I went thru my parts box and found 2 brands of 1" steam valves:

    1. Plumbers edge - home depot brand. This is the valve I installed and the radiator leaked.
    2. Bluefin - supplyhouse.com brand. I put this valve on and it fit much better. Just ran through a heat cycle and there are no leaks.

    I tried my Bluefin 1 1/4" valves on my larger radiators. They do not mate properly. I'll pick up the home depot valves and see if they mate.

    Are there a handful of spud/valve mates, or does each manufacturer make their own.

    Thanks for the quick and informative responses.

    Pics 1&2 Plumber edge valve that didn't work.
    Pics 3&4 Blue fin valves that worked.

  • KC_Jones
    KC_Jones Member Posts: 5,736
    The valve and the spud are essentially a matched pair, if you replace one, you replace the other. This is also why they are sold as a pair. If a mismatched pair happens to work, I'd say it's coincidence and can't necessarily be predicted.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • branimal
    branimal Member Posts: 210
    edited January 2022
    Looks like I'll need to remove the old spuds in my rads and replace with the new ones that came with my valves.

    I've watched a few youtube videos and see a couple of ways this could work:

    1. Cut the union nut off and put a pipe inside the spud to act as a support (3/4 black pipe). Then take a pipe wrench with a cheater bar and crank off the spud. The brass spud should collapse around the black pipe, which will allow the pipe wrench to get a grip on the spud. I could hit the spud with heat and/or pb blaster. (Though not sure spraying lube inside the rad is a good idea.)

    2. Sawzall off the spud almost flush with the radiator's bushing. Leave the spud about 3/8" proud of the bushing. Then using a sawzall, make two relief cuts on the spud's internal threads. Proceed to hit the 3/8" proud section of the spud with a hammer and cold chisel. Or remove with a spud tool.

    Any thoughts on how I should proceed?

    Also, can anyone recommend a good spud tool? I think I need one to install the new spud. Seems like the one at Home depot get's garbage reviews.

  • ethicalpaul
    ethicalpaul Member Posts: 5,701
    edited January 2022
    The spud tools at HD are probably rated as garbage because people are trying to use them to remove spuds which they obviously won't do no matter how good they are (to be fair it's only obvious once you've removed one the right way and know better).

    I have had very good results installing new spuds with a junk spud tool from Amazon that I'm sure is equivalent to the big box ones.

    For removal, I cut off most of the spud, leaving like 3/8" sticking out, then I cut the slits CAREFULLY down to near the threads and chisel them out like a couple of the YouTube videos. I have definitely nicked the threads doing this but never anything that a little teflon tape couldn't cure.
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
    EBEBRATT-Ed Member Posts: 15,512

    Try the easy way first spilt the nut by cutting and get that off. Find something to fit inside the sputd to keep it from collapsing, a wooden dowel, metal bar etc and try wrenching it out. If not then try the cut and chisel. You can try the spud removal tool first
    JUGHNE Member Posts: 11,058
    The spud tool is handy as it will break off the internal ears so you can get your insert pipe inside. ;)

    Actually I always try it. I have been surprised several times. 1 1/4" spud unscrewed out of 70 year old steel coupling. Sometimes smaller spuds will unscrew....1/2 to 1".

    If not then the cut chip method.
  • branimal
    branimal Member Posts: 210
    I gave the spud removal a test run with an out of service radiator with a cracked vent boss. Using the spud removal tool and and 18" pipe wrench and a cheater bar - the spud and the bushing came right out.

    Radiator 1: the spud removal tool pulled just the spud out.
    Radiator 2: the spud removal tool cracked the brass nubs, but not completely so i couldn't wedge in my dowel. I cut the nut off with a grinder. Heated up the spud with mapp gas for 2 miuntes and used an 18" pipe wrench and a cheater bar. And the spud only came out.

    Replaced the spuds with the 18" wrench and pipe dope. Ready to put these rads back to work.

    Thanks for the help guys!