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Massive Carbon Deposits (?) on gas boiler sections

Albany ChrisAlbany Chris Member Posts: 28
I was just at one of my rental properties for an unrelated problem and smelled a strong combustion smell in the basement. I felt the warm combustion gasses spilling out of the front of one of the two boilers and when I removed the front panel saw flames slightly licking up the front panel of the boiler with heavy soot deposits there.

I found crazy heavy black deposits on the front sections of the boiler (picture attached) which looked like they were mostly blocking the flow of heated air through the boiler sections in the front of the boiler and likely causing the spillover. The back was pretty clean. There were also black deposits in the intakes of the outer two of the 3 boiler tubes. (pictured).

The other boiler seems to be drafting fine.

The boiler is a Pennco of indeterminate age. Both boilers exhaust into the same flue. I shut off the boiler for the night. I am a landlord and have installed many boilers and troubleshoot them. I know more than most landlords but much less than you guys.

Can I clean off the heavy deposits to restore the airflow?
Suggested cleaning technique?
What could be causing this massive buildup of Carbon or whatever on the boiler sections ?
Is the buildup behind the air shutters in the boiler tubes from exhaust gas being pulled into the boiler tubes?

Thanks for your help, I need to get their heat back up tomorrow if possible.


  • HVACNUTHVACNUT Member Posts: 2,628
    edited December 1
    The only thing you absolutely need to do is have a PROFESSIONAL diagnose and repair the boilers.
    Unless you have a combustion analyzer, and have the qualifications, you shouldn't be touching them. Installing boilers doesn't count. For the safety of the tenants and possibly a wrongful death suit against you, don't touch it. Shut it down, turn off the gas, and get a Pro ASAP. A Sunday service rate is a lot cheaper than the alternative.
    There's no excuse for such neglect. It can't be about the bottom line when lives are at stake. Sorry to be blunt but this is why Slumlord is a word.
  • mattmia2mattmia2 Member Posts: 388
    Also why in most states you are only allowed to do trade work as the homeowner on your own property if it is a single family residence and it is your own residence.
  • nicholas bonham-carternicholas bonham-carter Member Posts: 7,965
    edited December 1
    Those deposits didn’t just happen overnight.
    Possibly there is not adequate combustion air, or the flue has been blocked for a long time.
    You do not want this to happen:
  • DZoroDZoro Member Posts: 934
    That is a Carbon Monoxide bomb! Turn it off and like the others said call a professional before turning it back on. Your in great danger until it is repaired professionally. Your CO alarms should be going off...
  • ch4manch4man Member Posts: 165
    pretty harsh responses Chris, I'd like you to understand a bit why. there are a few conditions that can cause this dangerous condition, to prevent its return needs to be addressed.
    do not touch it. the soot inside the burners is one clue the pro you hire needs to see.

    i see a possibilty of issues more serious than simple dirty burners that only trained experienced pros will have. ( not to discount your current knowledge, but you need some one who doesnt need to come here for answers)

    besides soot balls like that being vacuumed out with a standard shop vac will just blow right through the bag as a fine layer of soot dust throughout the house. ive heard of soot damage cleanings exceeding $20K. that alone, let alone the the CO dangers just does not make it worth it for you to tackle
  • Albany ChrisAlbany Chris Member Posts: 28
    Thanks for most of your responses, especially on a Sunday morning. As noted I did shut it off last night and I realize the CO danger. The first floor CO alarm hasn't gone off but frighteningly the second floor had disabled theirs due to the low battery alarm (replacing today).

    If only I had more confidence in hiring a "professional". I had an old timer I trusted but he retired and the other guys just want to swap parts and leave as soon as possible. Then keep coming back if that didn't fix the problem. I need to use my network to find someone decent I can trust.
    Despite CH4man's useful advice my plan will be to clean it today and get it running if it is drafting correctly and then find a recommended technician and have them come out this week to troubleshoot the combustion problems. I don't think I will get the right person randomly on a Sunday and they would probably be more rushed on an emergency call. I will take a few more pictures of the soot before removing it and take some extra CO precautions with ventilation and a CO detector in the basement in addition to the ones upstairs.

  • DZoroDZoro Member Posts: 934
    We are just concerned because you have a very dangerous situation. It is to be taken seriously.
    The chances are that by just cleaning, will not solve the problem. The problem more than likely something much deeper. Some possibilities were mentioned.
  • SuperTechSuperTech Member Posts: 949
    That's bad. Like really bad and dangerous. You need someone who has a manometer, digital combustion analyzer and the experience to know how to use them to diagnose and correct the problems. You are putting your tenants lives in danger by attempting to correct it yourself.
  • STEVEusaPASTEVEusaPA Member Posts: 3,481
    That's the worse gas situation I've ever seen, probably by a factor of at least 10.
    If I owned the company that was called to service that boiler, I'd consider it an excellent learning/training opportunity. Bring everyone over, completely rip it apart and fix/clean.
    Evaluate/investigate the chimney, combustion air, things pulling combustion air out of the mechanical room, spilling out of vent hoods, etc.
    And of course combustion testing/and tuning with at least a few personal CO monitors on the entire time.
    A small apartment building is likely to have either a commercial dryer, or 2 or more regular dryers. And I'm sure they are sucking all the combustion air out of that basement/mechanical room as well as most of the building.
  • HomerJSmithHomerJSmith Member Posts: 714
    edited December 1
    Pay attention to these professionals. They only have you best interests at heart.
    Just think, how would you feel is someone died on your property, and thinking, if I had only...
    Bad things happen when people make bad decisions.
  • Albany ChrisAlbany Chris Member Posts: 28
    Thanks again for all the feedback. I did the initial cleaning. As I said I will have someone out this week to do a full diagnosis / tuning/ cleaning / repair. In the meantime I have a window open in the basement with a fan creating negative pressure and another window cracked open to supply makeup air, plus extra CO detectors.

    The chimney is not blocked and there should be plenty of makeup air in this full basement in a 1905 house. There is another boiler, 2 water heaters and one dryer which is typical for the thousands of two family houses in Albany. So I am curious as to what is causing the problem. I will report back.
  • ch4manch4man Member Posts: 165
    stop helping!
  • Jolly BodgerJolly Bodger Member Posts: 132
    @Albany Chris realize you have documented that you are doing work illegally. Your liability is through the roof right now. If one of your tenants saw this they would have grounds to sue you even without anyone getting harmed.
  • JUGHNEJUGHNE Member Posts: 6,178
    By now, we all hope you got pro help.
    Would you let us know the outcome?
    My best guess is low gas pressure and/or plugged gas orifices.
    Fire burning inside the the burners. Maybe not enough draft also.
  • icy78icy78 Member Posts: 274
    edited December 5
    @Albany Chris
    Google NCI certified combustion analyst in your area.
    I did. There are guys near you. (If its Albany NY)
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