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Carlin G3B Combustion Problem

Long Beach Ed
Long Beach Ed Member Posts: 1,315
edited December 2022 in Gas Heating
We're looking at a Dunkirk 160,000 BTU oil boiler outfitted with a Carlin G3B burner twelve years ago. The installation then was a breeze, and with somewhere around 9% CO2, 0 CO and 475 stack temp.

Back there to clean the gun 12 years later and find 1200+ppm CO. We open the air shutter until it goes down to 20ppm only to find the CO2 at 6%. Close the air shutter a hair and the CO soars back up. Close it more regardless of the CO and the CO2 doesn't budge from 6%.

Checked the gas pressure on the outlet; 3.5" wc. Clocked the meter, 160,000 as should be.

Wet base 37 year old boiler with no chamber could be sucking air from somewhere? But where? It was fine a decade ago.

Where can we start?

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,410
    Pull the burner out and check the end of the burner
    rick in Alaska
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,315
    edited December 2022
    I brushed it down from inside the tube and brushed down the end but I didn't look at the outside. Glanced around the firebox. Will take a better look tomorrow. Thanks, Ed.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,410
    some parts for that burner are no longer available
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,315

    some parts for that burner are no longer available

    Probably the one I find out I need.
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,315
    edited December 2022
    Pulled the gun. The firebox is clean. Insulation up tight against the front. Front of gun pretty much flush with inside of door. Screen on the gun is clean. Checked again, 40ppm CO; 6% CO2. Try cutting the air and the CO soars. CO2 remains the same no matter what.

    Meter clocks at 160,000. Orifice correct. 3.5" wc out. This once worked like a dream... This isn't good.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,323
    I wonder how it might work with a ceramic fiber target wall and a blanket on the floor? That boiler was designed to have that chamber in place with the old oil burner. Just a thought. As far as the low CO2, could you be getting dilution air from a bad seal on the breach, vent connector, or any of the other section seals?

    Last but not least. Is the test equipment calibrated properly? Double check it against a "known good" combustion analyzer.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,410
    What is the boiler water temp? Firing into a cold boiler will increase CO especially with no chamber.

    Maybe Carlin will have an idea
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,315
    edited December 2022
    The section seals could be gone. It's a radiator-type 1975 boiler. I don't want to start playing with the firebox because it worked fine set up exactly this way 11 years ago. All that could have changed would be air leaks, I suppose. We ran the boiler well into creating steam but nothing changed. Even got new fluid for my old Fyrite wet gauge and it came up the same. Thanks for the ideas, gentlemen. This one's got me stumped. Let me know, please if you think of anything else. As a last resort, I'll reach out to Carlin, but I feel stupid.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,410
    Maybe take the jacket off and see if you have air leaks between the sections. 37 year old boiler the rope between the sections could be compromised
  • Big Ed_4
    Big Ed_4 Member Posts: 3,012
    A few burner field techs that I talk to , whisper to pull the target chamber .

    Funny how some converion burner jobs work great and some don't.

    It's time to change the fluid if the reading goes up after another flip .

    There was an error rendering this rich post.

  • Long Beach Ed
    Long Beach Ed Member Posts: 1,315
    edited December 2022
    The chamber's out of there. Been out since the conversion, Ed. Worked great when set up. And I put new fluid in that silly thing, tested it two, then four. Blew in it and tested my breath twice, double... all that stuff. It's just saying "no more"!
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,315
    Any new thoughts on this? Still trying...
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,515
    Maybe Captain CO Jim Davis will see this.  Maf Dog
    Long Beach Ed
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,315
    Still working on this one. Anyone have any thoughts?
  • Big Ed_4
    Big Ed_4 Member Posts: 3,012
    edited March 2023
    I set them up with O2 not sure how to convert fromCO2 . The EZ sweet spot is between 4-5 O2 if the CO reading allows . What percentage are you firing at ?

    There was an error rendering this rich post.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,410
    Co2 or O2 whatever you use does not matter. You can use either one. Most measure O2 with the modern analyzers and convert to Co2 automatically.
    Mad Dog_2
  • Big Ed_4
    Big Ed_4 Member Posts: 3,012
    What percentage is it firing from max ?

    There was an error rendering this rich post.

    Mad Dog_2
  • captainco
    captainco Member Posts: 796
    O2 on gas power burners should be 4% to 6% or CO2 8% to 10%. Usually air leaks do not cause high CO just high O2 and low temperatures. The flue temperature might help. Is there a draft reading? Underfiring certain burners creates poor mixing but this sounds like it is in a range that should be acceptable. Not sure if there is anything in the airtube that can warp or be out of position? However that don't explain the drop in CO2. Need temperature and draft.
    Mad Dog_2
  • rick in Alaska
    rick in Alaska Member Posts: 1,466
    I the burner fan dirty?
    Rick
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,323
    I am just spitballing here. When the burner was new you were able to get 9% CO2 and 0PPM CO at 475° stack temperature. The fan was new, and clean, the air gate adjustment was new and clean, the mixing plate at the end of the burner was new and clean. If the fan has 12 years of household dust build up and the air adjustment has some dust on it I'm sure the static pressure of the dirty fan and air adjustment is different from the day it was new. How well did you clean the burner on the last maintenance? did you actually brush all the dirt off of the fan blades individually? Are all the air handling parts as clean as new? Sometimes it is the simple things that are overlooked. You may need to look closer at the burner parts.

    Mr. Ed

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    kcopp
  • captainco
    captainco Member Posts: 796
    If it were the fan the CO2 would have gone up as the O2 went down.
    EdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,323
    edited March 2023
    captainco said:

    If it were the fan the CO2 would have gone up as the O2 went down.

    Agree ... BUT...

    One might adjust the air gate to compensate as each year of build up is added to the fan blades. Eventually the static pressure is effected and you can't open the air adjustment any more. Now we need to find out why.

    As I said... Just spitballing...

    I was taught to brush the fan blades on every tune up in order for the fan to be able to function as efficiently as possible. I have also worked on burners that were "TUNED UP" for years by technicians that were not taught this method. After cleaning a rather large pile of dust and lint off a burner fan, I was able to close the air adjustment by 50% and get a cleaner fire than when I arrived. Static pressure did a better job of mixing fuel and air. Of course I was taught this on oil burners, but the same amount of lint can clog up a fan on a gas burner.

    Just suggesting that someone look.

    Mr. Ed

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • Long Beach Ed
    Long Beach Ed Member Posts: 1,315
    Ed, we pulled the motor, really cleaned the fan, tube and screen at the end of the tube. This baby's clean.
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,315
    edited February 3
    Just noticed I never followed up with a cause to this problem. Further testing found Excess Air to be in the 90% range. Stripped much of the jacket and resealed the clean out plates with furnace cement. That's how this boiler is sealed. Brushed and vacuumed.

    Now it's running with 9.5% CO2, O2 of 4.6% Excess air of 28%, CO at 35ppm. Net stack temp is 491 degrees. That's called the 79% efficiency range. The boiler is a 50 year old Dunkirk with a Carlin G3B gas conversion burner.
  • Tim McElwain
    Tim McElwain Member Posts: 4,641
    Excessive air will do it every time!
    Long Beach Ed