Massive Carbon / Soot Deposits on gas boiler sections

Albany Chris

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.

HVACNUT

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.

mattmia2

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-carter

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:

https://www.cnn.com/2019/11/23/us/navy-veteran-dead-three-years/index.html

DZoro

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...
D

ch4man

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 Chris

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.

DZoro

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.
D

SuperTech

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.

STEVEusaPA

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.

HomerJSmith

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 Chris

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.

ch4man

stop helping!

Jolly Bodger

@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.

JUGHNE

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.

icy78

@Albany Chris
Google NCI certified combustion analyst in your area.
I did. There are guys near you. (If its Albany NY)

Albany Chris

Just wanted to follow up with the outcome here, though there may not be much to learn as we never really figured it out.

I had an experienced tech come out a few weeks ago. He was baffled by the soot buildup in front of the boiler but not the back. He check with a number of sources and nobody had seen that before. He suspected moisture in causing the soot buildup, but the soot was bone dry. He did a thorough cleaning and then a combustion analysis. O2 and CO2 were normal but CO was very high which he said indicated recirculating combustion air. THe boiler was then drafting properly but we didn't know what caused the soot buildup or the recirculating exhaust.

This boiler has the vent pipe / draft hood on the back instead of the top. Also of note is this boiler has been raised up on concrete block due to basement flooding 8 years ago) and there is no floor to the boiler - so the air can now come up through the open bottom around the blocks instead of just being drawn in through the front.

I put a "floor" in the boiler to minimize the air intake through the bottom. We were planning on doing more combustion analysis with the floor installed and with partially closing off some of the large draft hood opening. However the combustion gasses started spilling out the front again with occasional small flames starting to lick out. I ordered a new boiler. It will be installed this week.

btw, Both apartments have been empty for the last few weeks and the other boiler is drafting well.

Thanks to those who posted and contacted me directly.

Intplm.

@Albany Chris I have a question.
When the boiler was raised up off the floor years ago, was the piping attached from the factory that's on the draft hood cut to accommodate the smoke pipe?

rick in Alaska

If you put a "floor" under it to block intake air from coming in under it, you probably made it worse. I haven't been around many atmospheric boilers, but from what I remember from Tim Mclwains (SP?) gas class, the way they sit on the floor is critical to the way combustion air enters it. I would look at the installation manual for that unit and find out what it says about it. It could very well be it needs the bottom fully open.
Rick

SlamDunk

I'm late to the conversation but that's not carbon deposits. That is what I call klinkers.

Alan (California Radiant) Forbes

I've only seen one boiler with that much soot. It was a Crane Basmor model, probably 80 years old, heating recessed cast iron convectors. I never got to the bottom of why it was sooting up, but I suspected that it was condensing and the moisture on the sections was collecting products of combustion - over 80 years.

The soot was very fine and went everywhere when we cleaned it.

Replaced it with a TT Prestige Solo.

Intplm.

rick in Alaska said:

If you put a "floor" under it to block intake air from coming in under it, you probably made it worse. I haven't been around many atmospheric boilers, but from what I remember from Tim Mclwains (SP?) gas class, the way they sit on the floor is critical to the way combustion air enters it. I would look at the installation manual for that unit and find out what it says about it. It could very well be it needs the bottom fully open.
Rick

Thats some of what I was asking about earlier.
If the draft hood was cut or altered, it could have contributed to this.
Similar to the floor issue you mentioned.

retiredguy

Everyone that has posted a comment or an answer has concerns for your safety and are pretty much spot-on. There are many things that can cause your problem. Let me add a couple observations. These type boilers were common when I entered the boiler service industry. Anyway, I noticed that the air adjustment plates in addition to the boiler sections, in the middle picture have soot on them. I have found that this is usually caused by 1 of 2 problems; 1) a leaking gas stop valve that is worn out and needs replaced causing the gas to burn at the end of the orfices when the gas is supposed to be totally shut off; 2) worn out gas orfices. In addition, the soot on the cast iron sections may be caused by the sections being too cold which could be from low gas input, improper air/fuel adjustment, poor draft through the boiler proper, insufficient combustion air, or too much sediment in the bottom of the boiler sections. Too much combustion air is rarely the problem. The answer to the exact cause of the problems may be very elusive. Good luck

clammy

I got one vote in w retired guy ,I have also ran into this issue and after I exhausted logical troubleshoot that after cycling the gas valve a few times got it to replicate a cycle of the gas valve bleeding through .the boiler was quite old and they finally had me change it it was not worth doing a gas valve pilot assembly and new aquastat and again pulling her apart to clean .afyer replacement all was good and never a soothing issue again .aswith yours soot only on front of boiler sections but plugged Peace and good luck clammy

Albany Chris

Thanks again for the comments.
- The draft hood was not modified when the boiler was elevated - though obviously there is less rise before entering the brick chimney.
- Floor - the boiler was sitting directly on the concrete floor before so it seems that adding a floor merely replicated the original airflow.
- The gas valve is an interesting idea. It is sticking now and doesn't always turn on without a light tap. (another contribution to the just replace it decision). I haven't seen any small flames though when the valve is off and we have spent a lot of time there.
- I think the soot on the air adjustment plates is from the recirculating exhaust gas being drawn into the burners, especially when it was heavily rolling out. Sediment in the boiler sections is interesting. This used to feed CI radiators but has fed baseboards for at least 10 years so there wouldn't have been condensation from cold returning water.

It will be gone tomorrow.

ch4man

Albany Chris said:

Thanks again for the comments.
- The draft hood was not modified when the boiler was elevated - though obviously there is less rise before entering the brick chimney.
- Floor - the boiler was sitting directly on the concrete floor before so it seems that adding a floor merely replicated the original airflow.
- The gas valve is an interesting idea. It is sticking now and doesn't always turn on without a light tap. (another contribution to the just replace it decision). I haven't seen any small flames though when the valve is off and we have spent a lot of time there.
- I think the soot on the air adjustment plates is from the recirculating exhaust gas being drawn into the burners, especially when it was heavily rolling out. Sediment in the boiler sections is interesting. This used to feed CI radiators but has fed baseboards for at least 10 years so there wouldn't have been condensation from cold returning water.

It will be gone tomorrow.

it is not recirculation, i suspected and now you've confirmed a faulty gas valve. this is a pro repair only so i only agreed than you need professional service.
i'm glad everything is working out for you now. dont let anyone modify your new boiler. that only covers up the real issue and many times makes it worse

icy78

A properly done combustion analysis whouldve shown that gas valve problem.
Did you try the NCI google I suggested?

Thanks for updating too BTW.👍

tim smith

1st, did you all pull the top of the boiler and rod out the pin heat exchanger completely? We have seen many boilers like this with people who neglect their equipment. 2nd, did you brush and poke out all the holes on the cast iron burners, (carefull not to enlarge. We usually then wash them out, blow them out with air and reinstall. We have found many people don't do thorough job on cleaning heat exchanger and burners and that will throw high co #s. The sticking gas valve is another issue that must be addressed. Sounds like you are curing it with a new boiler.
Good Luck
Tim