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Corrosion around LWCO - possible drip

This is steam boiler that would have never worked correctly if not for the help from people here, 5 years ago. Thanks to all of you!

Anyway, while doing the first blow-down of the season I noticed this corrosion around the LWCO. I did not notice this last year or even pre-season this year. From the attached photo it seems like joint that connects up with the site tube could be leaking (notice the crust on the wires). It also seems possible that there is another drip on the upper connection the boiler which is causing corrosion on the lower pipe.

My question is: is this just a sign that the joint wasn't tightened enough or not enough dope being used OR does this indicate some other problem(s)?


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,840
    edited December 2020
    Is there a pipe or fitting just above that area that may be leaking? since it is steam, any water that drips on that area (while the boiler is operating) will instantly evaporate leaving the minerals and sediment from the water behind.

    If not then the most likely candidate is the compression fitting at the top of the 90° brass tube bend. I would not touch it unless you have a replacement tube, nut, and ferrule for both ends.

    You can carefully wire brush the area to clean it up. Do this when the boiler is off and cold. Plumbers grit cloth, Steel Wool, or Bronze Wool will also work nicely. Once it is clean, you can monitor to see how quickly or slowly the discoloration returns. Unless you are actually seeing live steam leaking while the heater is operating, there is no need to be alarmed.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    EBEBRATT-Ed Member Posts: 15,529
    You have a leak. It's a small one that you probably can't see. It leaks so little that when the boiler is hot it evaporates so you don't see any water and the minerals and corrosion are all you see. It looks like the union on the top connection and the top compression fitting from the LWCO are leaking
  • Fred
    Fred Member Posts: 8,542
    That brass pipe is a vent tube for the LWCO. I'd watch that area while the boiler is running and see if you see any steam escaping from any of those joints and condensing, dripping down to the other areas