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Steam Leak out of Steam Main

csricecsrice Member Posts: 3
Hello Heating Help community,

This past spring, I converted my oil boiler to a gas boiler. I live in Queens, NY - and went with a contractor that was highly rated. Yesterday, I fired the boiler to make sure it's ready to go for the real cold season. It worked mostly fine, but had some steam and oil come out from the relief valve. That only lasted five minutes, and the boiler worked just fine and it warmed the house up within 30-45 mins. I assumed the small amount of oil was the last remnant of oil left over from skimming.

Today, I fired it up again to make sure the relief valve didn't have a repeated issue. There was no steam/oil/water coming from the relief valve.... but, after running for an hour, I now I noticed a steam leak from the main black pipe out of the boiler (video attached below). I emailed my contractor to come back out to fix it, but thought this forum might be able to provide some insight into whether I should be upset with my contractor. Some details of my heating setup/home:

-Weil Mclain EG 45 gas boiler
-1300 sqft home
-3 stories
-8 Radiators
- Pressuretrol settings :

-Cut in settings:

-Video of brand new pipes leaking:

I'm an IT tech by trade, steam heating is a foreign concept to me, so I apologize in advance if I used an incorrect term to describe my issue. I understand these setups are complex, and minor tweaks and maintenance can fix some problems. Should I be extremely worried about this steam leak from the main pipes out of my brand new boiler?

Thank you,


  • Jamie HallJamie Hall Member Posts: 13,182
    Well... you shouldn't be extremely worried -- in the sense that this should be fixed yesterday if not sooner -- but if it's leaking, it's not right. Fortunately, your contractor did a very nice job of putting things together, so he or she should be able to tighten it up.
    Br. Jamie, osb

    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
  • mattmia2mattmia2 Member Posts: 1,706
    so it is just the union that is leaking?
  • BobCBobC Member Posts: 5,120
    The pressuretrol looks fine, just make sure the second one has the white dial under the cover set to one.

    It looks like the contractor took the care to make sure it was all done right, maybe they just forgot to snug up that union. if you have a large enough wrench you could try tightening the big nut yourself but it might take a 3 ft wrench.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • csricecsrice Member Posts: 3
    Thanks for the replies all, has eased some of my stress.

    @mattmia2 - Yup, it's just the union that's leaking.

    @BobC - I don't have a 3 ft wrench, just an 18 inch crescent wrench. I'm still requesting my contractor come out to tighten up this union.
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