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Black Drip Marks on 2nd Flr Riser (New radiator installed above 3 yrs ago)

Hi all, thanks for sharing your knowledge and advice here. It is greatly appreciated!

We have 1 pipe steam. Boiler replaced end of season 4 yrs ago. New one has mud valve but no skim port. We then did some renovations on the 3rd flr, leveling in new 3/4" subfloor w 3/4" hardwood over that. All radiators were replaced with properly sized newer units fitted to existing steam lines w factory nipples and new valves. Plumber used black dope and probably no wicking or teflon on the nipples where they met the old pipes. On initial fire up there was noise, lots, and leaking spitting vents on other floors too. That's when I got Dan's book and slowly got things sorted out. The following two seasons were warm and mostly quiet, but at the end of last season a small black drip mark appeared on the 2nd flr. riser. I figured a little excess dope on the connection above the ceiling had melted and worked its way down. But after a cold snap this Thanksgiving night (17 degrees) when no one was home this happened (see photos). Also drip marks on the other side of the riser wall below the 3rd flr radiator. Haven't been able to reproduce a leak at the 3rd flr nipple or valve but there's one photo shows what could be slight water staining on subfloor where the nipple enters. I should say that we did a setback on the thermostat this year of 4 degrees overnight. Towards the end of last season the vent on the radiator above that riser was buzzing a bit. (wet steam?) There's a lot of wood under that radiator and a beautiful 100+ yr old tin ceiling where the riser goes up on the 2nd flr. so I'm really hoping not to have to tear any of that out to deal with this. Would appreciate any advice you could share.

Many Thanks!

PS-The Co. that did the install now closed and unreachable.

Some relevant facts and photos below.

-3 story residential bldg.
- new boiler install never skimmed, wet returns not flushed either, lots of black water whenever I flush from mud valve
-Cut in looks to be between .75 & 1psi, Pressuretrol just below 10psi
-0-30psi gauge never moves off the 0 pin even when boiler is firing



  • 1. That 0-30 psi gauge could still not move when your pressure is too high, so you need a 0-3 psi gauge on the same tee as the pressuretrol to keep it honest, and below 1.5 psi for basic function, or 2 ounces for economy.
    2. Those pressuretrol pigtails need to be taken off, and inspected yearly to ensure they are not clogged. When reassembling, make sure the pigtail is brass or copper.
    3. When the inlet valve was replaced, was the old spud changed as well for the new one which came with the valve? The old spud will not seal perfectly with the new valve.
    4.Is the valve fully open?
    5. Download the installation manual, and prepare to install the skimming port after the winter.
    6. Let’s see pictures of the piping layout.—NBC
  • Jamie HallJamie Hall Posts: 10,279Member
    Well that's tiresome. Can you take a few straight on photos of all the joints and valve and unions around the top of that riser and the new radiator? Something is leaking just a little bit there, and perhaps with the photos we can figure it out.

    As to the damage to the tin ceiling and wood -- I doubt that any of that will have to be removed to fix the problem. There are other ways to get after that. The drip marks can probably be removed almost completely by careful, gentle cleaning and, if they remain, when you repaint the space they should be covered with a high quality shellac based primer, such as Zinsser's B-I-N, which will block the remaining staining from coming through to the finish coat. Been there, done that...

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • OldHomerOldHomer Posts: 4Member
    Thanks for the quick response and advice! Here are some pictures of the radiator and boiler piping.

    It's the new spud that came with the valve. Valve fully open. No obvious signs of leaking except possible moisture stains where the nipple passes through the subfloor. Finish floor is clean and dry. Sounds like you suspect excess pressure. Can that cause this kind of dripping? Pressuretrol pigtail is copper. If clogged can I just clean and reinstall or better to just replace? It would be great if this could be solved at the boiler.

    No union on the riser. It's just a clean run of pipe floor to ceiling. Any connections are above the tin ceiling. My best guess is there's an offset up there of 6-8" consisting of an elbow atop the riser with a couple of horizontal nipples and elbows to get to the vertical nipple that goes to the radiator valve. Unfortunately I don't have photos from when it was open. The only way to get a peek at those now short of ripping up floor or ceiling would be to send in a camera snake through a small hole behind the riser or down from above at the subfloor. A tricky task. I'm really hoping getting the pressure down at the boiler would solve this.

    Looking on the bright side it's just this one riser. Rest of system is working fine.

    Here are the photos... Thanks again!

  • KC_JonesKC_Jones Posts: 4,093Member
    The boiler ins't piped properly, and will certainly be making wet steam the way it is. This could be contributing to the problem if the steam is wet enough it cold have corroded some of the piping causing the leak.

    Also that rad is technically too close to the wall, optimal performance places them 2" away from the wall. Looks like it's relatively tight to that 3/4" baseboard.

    IMHO you should resign yourself to the fact that you have a leak, while and inspection camera is a fantastic idea, all that will do is show you where you need to start cutting.

    I would also suggest, the person you have had working on it may not be the most knowledgeable, especially if they are the one that installed that boiler. If that's the case I would suggest you attempt to find someone that knows what they are doing.

    Where are you located?
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • ethicalpaulethicalpaul Posts: 661Member
    That looks like the tiny radiator I just got from AFSupply, but this one is even tinier at 8 sections instead of 10 on mine. Couldn’t find a manufacturer name anywhere. Mine stinks like crazy when it gets steam. I hope both of ours put out enough heat, and good luck with your leak 😓
    1 pipe Utica 112 in Cedar Grove, NJ, 1913 coal > oil > NG
  • FredFred Posts: 7,814Member
    Needless to say (and as has already been said) the near boiler piping is all wrong. That aside, if that pigtail on the Pressuretrol (the gray box, not the one with the clear front) is clogged, it could be letting the pressure rise high enough to cause leaks in places where it otherwise wouldn't leak. Given you used a 4 degree setback, the boiler would have run long enough to let pressure build well beyond what would be typical during a normal heat cycle. Check and clean the pigtail. The boiler also needs to be skimmed so you need a skim port. I see what looks like a lot of crud in the bottom of that sight glass and the water level looks low. Was the boiler running when you took this picture. Water level should be about half way up the sight glass when the boiler is idle.
  • OldHomerOldHomer Posts: 4Member
    edited December 2018
    Thanks for the comments!

    Any recommendations for a good steam mechanic in the area?
    We are in Ridgewood, Queens, NYC.

    Could someone tell me what they did wrong with the near boiler piping? I have to make sure I don't get another messed up job. I'm really stressed out over this and worried it could happen on another riser.

    Would dialing back the pressuretrol down to 5 from 9 help eliminate excess pressure buildup with no adverse effect on performance?

    KC- I'll get that 0-3psi gauge on there as soon as I can get one. It would go on the same tee as the 0-30 psi gauge right? Inspection camera for where to cut info only. I fear the riser is on the other side of wall from radiator and don't want to open below if I can avoid it. Breaking out old elbows/nipples under the wall and between joist will be tricky. If I'm lucky it'll just be a union under that nipple to the valve.

    Fred- crud on sight glass is just residue on the glass. I just flushed the mud port a bit before taking the photo. Boiler wasn't running when I took that photo. Water level in sight glass stays about half way up during normal operation. No bouncing

    Thanks again for sharing the advice!
  • Erin Holohan HaskellErin Holohan Haskell Posts: 999Member, Moderator, Administrator
  • ethicalpaulethicalpaul Posts: 661Member
    This video should show you everything you might want to know about near boiler piping. I just found it and haven't watched it yet, but considering the source it's a winner:
    1 pipe Utica 112 in Cedar Grove, NJ, 1913 coal > oil > NG
  • coelcanthcoelcanth Posts: 62Member
    i'm in ridgewood also.

    i had a hard time locating an available contractor through the site here when i needed work a few years ago.
    we ended up going with a local shop to do our replacement and i would say they got most of the way there to a good job. If I had been more educated at that time i probably could've asked more pertinent questions and seen things through to a perfect job (by the high standards on the site here)
    as it stands now, i don't resent the time to learn how to skim the boiler and improve the main venting or observe or adjust the pressure..
    i am glad to be more capable in monitoring and maintaining the system for the future.

    you can email me if you are not having any luck
  • OldHomerOldHomer Posts: 4Member
    Thank you and your father for starting maintaining this site. As I become more knowledgeable I hope to be able to give back to the community!

    Thanks for the link. That's exactly what I needed to see!


    Always happy to meet a fellow Ridgewooder! Seems there's a lot of old steam systems around here. I used a local shop too, now defunct, and ended up with dicey piping job. Didn't know anything about steam systems at the time. But I'm learning a lot from the community here. Thanks to all the helpful folks here :smile:

  • Erin Holohan HaskellErin Holohan Haskell Posts: 999Member, Moderator, Administrator
    Thanks, @OldHomer.
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