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High CO

STEAM DOCTORSTEAM DOCTOR Posts: 523Member ✭✭
History: hot water boiler being used to heat bath house. 500 mbtu. Has history of spill switch tripping. There is a duct that is supposedly connected to outside to bring in air. Owner hires someone to add fan to duct in order to increase air. Next day CO alarms start ringing. Spill switch does not trip. Owner hires different plumber who tests flue and finds 1100 ppm. Plumber cleans flue passage ways in between boiler sections. Flue CO goes down to mid 200s. Flue temp is 115. No CO in room. This morning I am there and CO alarm goes off. Ran home and get personal tester and there are 90 ppm in room. Shut boiler down. I am in middle of combustion training. Ideally we should get someone fully qualified to look over system BUT we are in hurricane sandy area and no one is around(in general there are not many qualified and reliable gas combustion people in this area). What is the next step. I can get my hands on combustion testers but I would need some guidance from the folks on the wall. Why would bring in more fresh air result in higher CO levels? Is it possible that the fan is pressurizing the flue and preventing the flue gases from entering the flue? is there too much cold air coming in which is lowering flue temps?
· ·

Comments

  • JStarJStar Posts: 2,437Member ✭✭✭
    CO

    Where are you located?



    My guess is a flue or draft problem.
    - Joe Starosielec
    732-494-4357
    j.star@thatcherhvac.com
    http://thatcherhvac.com
    http://facebook.com/thatcherhvac

    Guaranteed performance. Guaranteed energy savings.
    Serving all of NJ, NYC, Southern NY State, and eastern PA.
    Consultation anywhere.
    · ·
  • STEAM DOCTORSTEAM DOCTOR Posts: 523Member ✭✭
    queens

    This place is low on funds so they will hesitate if they have to spend big money( I know that doesn't make sense but its the reality). Why would the CO problem start after they put in the fan?
    · ·
  • JStarJStar Posts: 2,437Member ✭✭✭
    CO

    CO can be caused by too much, or too little air. Ideal combustion is a big diva. It is very particular.
    - Joe Starosielec
    732-494-4357
    j.star@thatcherhvac.com
    http://thatcherhvac.com
    http://facebook.com/thatcherhvac

    Guaranteed performance. Guaranteed energy savings.
    Serving all of NJ, NYC, Southern NY State, and eastern PA.
    Consultation anywhere.
    · ·
  • Steve WhitbeckSteve Whitbeck Posts: 669Member
    CO

    Any chance this a Slant Fin boiler? Biggest I have seen was 300,000 BTU.

    They have a lot of flame impingment on the heat exchanger. This causes high CO readings in the vent pipe.

    If the fan is pushing fresh air into the boiler room then somehow vent gasses are getting into the room.

    Any chance the air intake is down wind of the chimney?
    · ·
  • Steve WhitbeckSteve Whitbeck Posts: 669Member
    CO

    Any chance this a Slant Fin boiler? Biggest I have seen was 300,000 BTU.

    They have a lot of flame impingment on the heat exchanger. This causes high CO readings in the vent pipe.

    If the fan is pushing fresh air into the boiler room then somehow vent gasses are getting into the room.

    Any chance the air intake is down wind of the chimney?
    · ·
  • Steve WhitbeckSteve Whitbeck Posts: 669Member
    CO

    Any chance this a Slant Fin boiler? Biggest I have seen was 300,000 BTU.

    They have a lot of flame impingment on the heat exchanger. This causes high CO readings in the vent pipe.

    If the fan is pushing fresh air into the boiler room then somehow vent gasses are getting into the room.

    Any chance the air intake is down wind of the chimney?
    · ·
  • STEAM DOCTORSTEAM DOCTOR Posts: 523Member ✭✭
    WM 500000 atmospheric hot water boiler

    I dont know much more then that. I hope to go tomorrow or next day to do some detective work. Is there a way positively determine if there is too much air coming in?
    · ·
  • KCAKCA Posts: 264Member
    edited November 2012
    It may be a matter

    of cleaning the boilers heat exchanger...  Often when I see high CO ppm numbers it's because of a dirty exchanger..



      :-)  Ken
    · ·
  • STEAM DOCTORSTEAM DOCTOR Posts: 523Member ✭✭
    cleaned

    The heat exchangers were throuly cleaned at with point flue co went from 1100 to 250. Boiler was runnning for few days before co alarm went off
    · ·
  • JStarJStar Posts: 2,437Member ✭✭✭
    CO

    The biggest statement here is that somebody added the fan, and the CO went up. Turn the fan off, or get a refund.
    - Joe Starosielec
    732-494-4357
    j.star@thatcherhvac.com
    http://thatcherhvac.com
    http://facebook.com/thatcherhvac

    Guaranteed performance. Guaranteed energy savings.
    Serving all of NJ, NYC, Southern NY State, and eastern PA.
    Consultation anywhere.
    · ·
  • ColoradoDaveColoradoDave Posts: 54Member
    Cleaning may not be clean enough

    Early this summer, I was on a call to a 4 year old Buderus GC boiler (cast iron).

    I was brought in to clean the boiler.  The original installer cleaned it 2 years ago (again ONLY a 4 year old boiler) and got soot all over the place.  So we were brought in to clean it this year.  I pulled a ton of soot out of the boiler and had extremely high CO readings in the flue.

    Ended up having to pull the boiler out to the back yard and power wash the heat exchanger.

    That being said.... reinspect the heat exchanger.  If it's sooted up or built up condescent again... you may need to inspect the flue and combustion air setups again.  Perhaps an induction fan would be appropriate instead of a combustion air fan.
    · ·
  • STEAM DOCTORSTEAM DOCTOR Posts: 523Member ✭✭
    vent cap

    Went today to check out. Turns out that besides for the fan they always changed the vent cap. I had them disconnect the fan before I came. I did a basic smoke test. The smoke did a U turn when it came close to the vent. When I held the smoke next to the sheet metal part of the draft hood the smoke slowly moved upwards until it hit the metal then it lazily dissipated. When moved back towards the vent itself the smoke made its U turn again.I held a paper towel in the vent hole and it noticeably blew away from the hole. I took off the vent cap and the same thing happened. I was not able to put the previous vent cap on because it was bent out of shape. Is it possible that bifferant vent caps would result in backdraft? In the meanwhile the new vent cap is on and the boiler is off untill the "pro" comes back to fix his mess.
    · ·
  • JStarJStar Posts: 2,437Member ✭✭✭
    Vent

    I'm having a hard time visualizing what you just described. Can you make a diagram?
    - Joe Starosielec
    732-494-4357
    j.star@thatcherhvac.com
    http://thatcherhvac.com
    http://facebook.com/thatcherhvac

    Guaranteed performance. Guaranteed energy savings.
    Serving all of NJ, NYC, Southern NY State, and eastern PA.
    Consultation anywhere.
    · ·
  • STEAM DOCTORSTEAM DOCTOR Posts: 523Member ✭✭
    edited November 2012
    diagram

    Sorry but diagrams on computers are beyond the scope of my technical expertise. I would have to wait until my kids get home from school. Try this. Make some smoke(match, light some cardboard whatever). The smoke will rise. Put your hand in the smoke. The smoke will spread across your hand. Now make smoke again and this time blow on the smoke. The smoke will obviously be blown away from your mouth. This what is happening in my situation. When I put the smoke in the hole where the combustion gas is supposed to exit the smoke is visibly blown away. The smoke actually makes a U turn away from the hole. When I hold the smoke against my hand the smoke will move up into my hand.
    · ·
  • Patchogue PhilPatchogue Phil Posts: 225Member ✭✭
    down draft from flue?

    So you are experiencing a downdraft at the flue when you should be getting an updraft,  right?



    Is it very windy there?





    · ·
  • STEAM DOCTORSTEAM DOCTOR Posts: 523Member ✭✭
    Exactly

    There is some wind but not more then any of the other buildings in the area. The vent cap was changed but not sure why that would make difference.
    · ·
  • Patchogue PhilPatchogue Phil Posts: 225Member ✭✭
    Something is sucking or blowing air

    Either the configuration of the roof and flue (w/o the cap) is causing wind driven air DOWN the flue,  or something from inside is sucking air FROM the boiler room and that flue is the least resistance.



    What else is capable of pulling air down the flue?   Exhaust fans from connected rooms/buildings?    Water heater with power vent?



    Look around.  If you open a door to outside or a window,  does the down draft go away at the flue?











    · ·
  • STEAM DOCTORSTEAM DOCTOR Posts: 523Member ✭✭
    update

    I finally had time to go take another look. Did the smoke test again and there was a very obvious back draft. I shut off all the ventilation fans and HVAC units and there still is the same back draft. I went up to the roof and put a flame near top of chimney and the flame was clearly being sucked into the chimney. There was almost no wind outside. When I did the smoke test in the boiler room away from the flue the smoke acted normally. Something is obviously causing suction down the flue but I cant figure out what it was. Any ideas would be greatly appreciated.
    · ·
  • ChrisJChrisJ Posts: 3,465Member ✭✭✭
    edited November 2012
    vents

    I really don't have any experience with this being a homeowner and not a pro.  But the two things that came to mind is a radon vent system or some of these semi rip off dehumidifier systems like the wave system and humidex system.  The wave and humidex are just a large fan that constantly pulls air from the basement.
    Weil-McLain EG-40 connected to 392sqft of radiation via two 2" risers into a 3" drop header and 2" equalizer. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment Typical operating pressure 0.5 - 1.0 inch wc.

    Steam system pictures updated 1/25/15.
    https://picasaweb.google.com/thetube0a3/Boiler?authkey=Gv1sRgCImUxIqv9436MQ#

    Don't push the envelope, eliminate it.
    · ·
  • STEAM DOCTORSTEAM DOCTOR Posts: 523Member ✭✭
    shut

    Every single appliance with a fan was shut. I even shut the circulator thinking that maybe that was creating suction
    · ·
  • ChrisJChrisJ Posts: 3,465Member ✭✭✭
    chimney

    Can you kill the main just to be 100% sure?



    Also going by memory I recall the chimney should be something like 2 feet above the highest part of the roof. Is that the case?
    Weil-McLain EG-40 connected to 392sqft of radiation via two 2" risers into a 3" drop header and 2" equalizer. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment Typical operating pressure 0.5 - 1.0 inch wc.

    Steam system pictures updated 1/25/15.
    https://picasaweb.google.com/thetube0a3/Boiler?authkey=Gv1sRgCImUxIqv9436MQ#

    Don't push the envelope, eliminate it.
    · ·
  • RJRJ Posts: 421Member ✭✭
    flue size

    check your flue size per boiler specs,  also as Phil said look for negative press in and around boiler rm.  look for bathrm or kitchen exhaust fans. they may be on intermittenly.
    RJ
    · ·
  • STEAM DOCTORSTEAM DOCTOR Posts: 523Member ✭✭
    co

    I think that I had everything shut. I will go back when I have achance and kill the main just to sure. Lets say for arguments sake that one of the exaust fans or hvac units or whatever is creating negative draft in the building. How long should it take for the draft to stabilize after everything has been shut?
    · ·
  • STEAM DOCTORSTEAM DOCTOR Posts: 523Member ✭✭
    flue size

    I am getting backdraft even with the boiler shut. Incorrect flue size shouldnt create back draft with boiler shut down
    · ·
  • STEAM DOCTORSTEAM DOCTOR Posts: 523Member ✭✭
    uei eagle 2x

    Just got my first combustion analyzer. Still learning my way around the machine. For now I am able to do basic combustion analysis of flue gases et. Can the uei eagle be used to measure room positive or negative pressure?
    · ·
  • RJRJ Posts: 421Member ✭✭
    neg press

    Do you have a sealed boiler rm ?  check at the boiler rm door do you feel air being pulled from rm, if so get door to seal, also check this fan that was installed for fresh air, make sure fan rotation is right, make sure this fan and fresh air inlets were sized per code.   There is a company called Selkirk that can provide flue and combustion air tables. after shutting all external air moving equip.should only be a minute or so.
    RJ
    · ·
  • SWEISWEI Posts: 4,927Member ✭✭✭✭
    Eagle 2X

    Has a differential manometer which will easily read room pressure.  Put one probe outside the room and one inside and read the difference.
    · ·
  • STEAM DOCTORSTEAM DOCTOR Posts: 523Member ✭✭
    thanks

    Havnt had chance to go back yet. Does it make sense to test the draft directly in the flue? The boiler has been off for a few weeks.What numbers should I be getting? Also does it make sense to test the pressure differential of the flue from the roof? If yes what sort of numbers should I get? Thanks
    · ·
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