high CO heat exchanger question

younda

Had a home energy audit and the 27 year old Burnham Series 2 gas boiler tested at 70% efficiency with extremely high CO pegging his meter at 4000PPM. I had a service tech come over yesterday who cleaned the boiler saying everything looks fine. He cleaned the gas tubes and showed me how the heat exchanger looked from underneath and said it doesn't look carbonized or have any signs of leaks. He checked the draft which he said is great and put a CO probe in the vent to find 8000PPM. He claims there's no danger running since there's no CO in the room or house. I'm not confident this couldn't change rapidly and not sure I want to trust the CO detector this much. He's saying the heat exchanger must be clogged and needs to be cleaned out and that usually this isn't worth the expense and effort. If I must replace the boiler, I'll deal with it but I at least need to know what's happening and if this might be repairable.

Eric_32

I wouldn't run it like that. Disaster waiting to happen. Gas boilers can get dirty and require cleaning just like an oil boiler, usually not as frequently.

Things that can make it happen, lack of oxygen in the room the boiler is in. If the room is not large enough to supply combustion air, it will burn rich and can cause sooting even with gas.

Check out these pictures of a gas boiler I cleaned last year. It had never been cleaned and was over 20-years old. Cleaning the heat exchanger should lower the CO levels back to normal.

Zman

First, STOP, turn off the gas to the appliance.
Most manufactures high CO spec is 100-150
Any remotely qualified technician will red tag any appliance over 400.
Find a contractor that will scream into the phone and run right over when you say the words 4,000 PPM CO.
Seriously, turn it off, you have a very dangerous condition.

icesailor

Any "technician" that says that 8,000 PPM is OK isn't a technician but a dubber. He obvously doesn't know anything about gas burner technology or oil either.

He needs to attend classes with Tim McIlwaine. NOW.

He may have a Digital Analyzer, but he doesn't understand what it is telling him.

OBTW, on most Digital analyzers, if it registers 4,000 PPM of CO2, the instrument is flucked and needs to be sent back for calibration. I doubt that the instrument is even working properly. When was the last time it was serviced? How old is it? Does the Oxygen sensor even work?

Does the Service manager of the Boss even know that this guy is registering CO numbers in the 4,000 PPM range? My UGI hand help personal monitor will lock up and become useless if it hits 1200 PPM and I have to re-set it by pulling the battery.

If you don't get a satisfactory response, call someone else. Tell them that the last person said it was reading 8,000 PPM but that was OK. He'll probably burn tires getting there.

8,000 IN THE VENT!!!. Be sure to tell them that. And you were told that it was OK!!!!.

Tell them that.

SlamDunk

Just for perspective:

I have an IN5 residential gas boiler that is about five years old. I checked the flue gases recently and my CO was two ppm Air free.

My burners at my place of employment burn 25200MBH at high fire and has a CO reading 0f five ppm.

Your readings are off the chart.

younda

Thank you for responses. I got a call from the service supervisor today and he wants to send someone else "more technical" tomorrow morning. I suspect the first order of business is to shut it off for their own liability reasons (which is probably smart). From Eric's pictures, I'm guessing my boiler inside probably looks similar. It seems annual "tune-ups" don't actually clean this out. Why is it the people I call tell me that this unit is old and should be replaced (not told this here yet)? If I can clean it like it should be and get to 80 something efficiency with normal CO levels shouldn't I just clean this? What should I pay for this (2 hours labor?). Doesn't look difficult - almost a do it yourself project with the gas off but not sure how the boiler top is gasketed down or sealed.

John Mills_5

Just remember that 80% efficient reading on a combustion test is totally different than the 80% AFUE or annual efficiencies of today's cast iron boilers. While they may be able to get better than the 70% reading now, it still will be 60-70% in annual efficiency which is how much gas you pay for actually heats the house.

Some dealers use a "tune up" as a quick look-see at the product and a foot in the door to see what they can sell you. Others really tear into the unit and clean it if "a horrible mess". Modern units don't tend to get very dirty however. They burn so clean.

Horrible mess is what our old retired oil man (he's 80 now) called anything all sooted up!

captainco

It is mind boggling that this kind of ignorance still exists in our industry today. But then what subject is discussed the least by votech schools, trade magazines, manufacturers, codes etc.? Combustion testing!!! 8000ppm can cause death in less than 15 minutes. There might not have been any CO readings in the space while the guy was there but then based on his knowledge he probably didn't do that test correct either.

I sold many Burnham Series 2 boilers. If the CO was high they weren't venting properly. It is repairable. Unless you purchase a really high efficient 90% boiler, you may end up with the same problem. Don't blame the boiler, blame the installation. You have been quite lucky up to this point but then so were many others before the tragedy struck.

icesailor

FWIW, that bonnet that goes on the top of the cast iron top of the boiler is a big place for flue gas leakage and draft loss. Often sealed with stove cement that hardens like a rock when it is heated. In the photo's displayed by @Eric:, there doesn't appear to be any sealant. There can be cleanout access panels on the side of the boiler. Held on by a bolt and gasket where the gasket is worn away or broken. Slathered with stove cement. All cracked and broken. Anything is a DIY project. Some things are more DIY than others. For the inexperienced, this is NOT a DIY project. I personally basically only did oil. That gas boiler you describe isn't much different that a nasty oil ones I have done. If it is like I think it is, 4 hours could easily be spent on getting it right. Do you have cats or animals in the cellar? Animal dander is a major cause of burner air restriction.

If poorly adjusted gas burners could soot up like an oil burner can, there would be a different discussion about the Gas v. Oil.

billtwocase

Was he serious? The plug needs to be pulled on it until it is repaired or replaced

younda

Thank you again for all the responses. I had the boiler cleaned tonight and now at 12PPM CO and 81.8%. Cleaning is pretty straight forward and a DIY job (for real DIY type people who read up and learn before doing). The brushed white dust into the vacuum cleaner hose looked like a snow storm. I contacted a licensed boiler technician I met last year when I needed help on a local non profit oil heating system. I initially forgot about him and should have called him first. He walked be through it and had the testing equipment. Looked just like the pictures Eric posted for me.
Part of being a true DIYer is finding the proper resources first. I was pointed to this website by a Burnham person when I called for technical support to learn they only support licensed contractors, not homeowners. I completely understand why they wouldn't support Joe homeowner.
This homeowner (me) is kind of a dope since the top of this boiler hasn't been off in 27 years but since I've learned from this I want to follow up in case others find this thread.
As far as possible reasons why the boiler sooted up. I built the walls around this room and used the MA code for required vent openings on the lower and upper sections of the walls so I don't think it starved for air. Do I have cats - yes 2. But they don't come close to the shedding of my golden retriever of 12 years who has filled dozens of vacuum cleaner bags. I can't blame my departed pal for this though.

icesailor

Never underestimate the power or amount of animal dander.

You still may not have enough make up air to the boiler. If the boiler had ribbon burners, dander and dust can collect on the OUTSIDE of the spun and constrict it. The same applies to the air shutters. There are really only two ways to get high CO. Not enough air, or too much gas.

Did the guy take the burners out and inspect them for free airflow?

At least you have seen how it is supposed to be now.

OBTW, we have a short haired Bengal cat. My wife brushes the cat every day and takes a pile of dander out. Every day, after 7 years. If you have cats, you have airbourne dander.

j a_2

Any company that sends out an untrained, incompetent, person…to ones home, needs there heads examined….Owners please do your home work…..

Kakashi

I agree with everyone above me, I would have tagged and disabled it. If your house is tight, any bathroom exhaust fans or attic ones that are on or run a lot?

icesailor

Here's a place.

Look carefully at the gas spuds to see if there is any buildup on the face. If the dust/debris in the air is such, there is a backflow negative air pressure where the gas comes out and that negative space can allow an accumulation of that fine white/yellow powder. If they have ribbon type burners, the air is mixed with the gas inside the burner tube and the dust/dander/debris can be on any surface of the burner. That's why it is very important to take them out and carefully clean and inspect everything.

With oil burners, the fan can become seriously compromised inside the fan cage where the underside is under negative pressure and the dust and dander will collect and seriously compromise the positive pressure that the fan is supposed to provide. If you have to keep adding air to a burner, check the underside of the fan with a small screwdriver. If you can scrape debris off of the inside curve of the vanes, you have an air issue.

Tim McElwain

Improper training and a proliferation of DIY'ers is going to be a constant formula for getting someone killed. There is a complete protocol for checking in my case gas equipment from boilers, furnaces, water heaters, gas ranges etc. All should be checked by the heating tech going into the customers home. Even the oil man needs to check all fossil fuel burning appliances in the home when they are doing their annual checks and cleaning.