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  1. #1
    Join Date
    Mar 2007
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    Charlotte, NC
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    Default Can't explain BPM

    Bob, Dale, any other true chimney professionals...

    Help me to understand what causes this:

    Background: 1986 home with solid fuel burning masonry FP and 2-story exterior brick chimney on rear of house. Current owner has gas logs installed with glass door insert. Chimney cap present.

    While I believe it is related to a time that pre-dates the use of the current gas logs, what causes black particulate mater (BPM) to form on the upper part (in this case - on the rear side) of the chimney, just below the crown?

    More perplexing than that, why would BPM form just below the shoulder (on the left), but not completely down the side?????

    Thx,
    Dave

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  2. #2
    imported_John Smith's Avatar
    imported_John Smith Guest

    Default Re: Can't explain BPM

    Im strictly guessing, and I know you asked for a chimney expert,
    but
    Was this on the north side of the house?
    Shade, from the tree could also be a contributor.
    The brick corbelling detail at the chimney cap could be helping to keep the BPM from the side of the chimney, until it gets down to the transition where it runs down the side.

    My 2 cents, and you probably already have considered it.

    Do I need assertiveness training?


  3. #3
    Join Date
    Mar 2007
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    Charlotte, NC
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    Default Re: Can't explain BPM

    imported John Smith...

    "imported" from where ??

    I didn't note which way was North.
    Still curious though, why there was BPM on the BACK side near the top, and then not appearing again until the lower LEFT. As opposed to BPM on the LEFT at the top, and then due to the corbelling, not appearing until below the shoulder on the LEFT.


  4. #4
    imported_John Smith's Avatar
    imported_John Smith Guest

    Default Re: Can't explain BPM

    David, Im still leaning towards typical mildew. The area looks shaded, and it may likely be on the North side of the house. I use google earth or mapquest to try and determine which way the house is facing. I also have 2 gps units that I use in case the property isnt on either of the two sites above.

    The large trees I see in the picture lead me to believe there is probably shade in this area quite a bit of the time.

    I wouldnt get hung up on BPM (a term I havent heard until your post). If you dont see any damage to the building, bricks, mortar, etc. it doesnt really make that much difference.

    If you have a real burning desire to investigate further, consider putting a smoke bomb in the fire place. Size accordingly so as not to terrify the neighbors and local law enforcement.

    Good luck

    Arent we all imported?


  5. #5
    Join Date
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    Default Re: Can't explain BPM

    I think I got the "BPM" phrase from Bob Harper.
    Until you KNOW what it is (soot, mildew, ???), its black particulate matter.


  6. #6
    Join Date
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    Ormond Beach, Florida
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    Default Re: Can't explain BPM

    Quote Originally Posted by Dave Hahn View Post
    I think I got the "BPM" phrase from Bob Harper.
    Until you KNOW what it is (soot, mildew, ???), its black particulate matter.
    Yes, Bob H. told us of the use of the term BPM, but ... "mildew" *is not* BPM.

    So I'm not sure I would call it BPM either (in fact, I know I would not call it that).

    I would call it a black 'stain' - or even just a "stain", which "could be" BPM ... or anything else. Heck, under microscopic examination, it 'might not' even be 'black'.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  7. #7
    Jim Gecz's Avatar
    Jim Gecz Guest

    Default Re: Can't explain BPM

    When I see a gas conversion I automatically assume past draft problems. Not only do you have an exterior wall fireplace which can create a cold hearth, but then look at the height of the house to the chimney.

    Air flowing over the top of the house likely caused a positive pressure and draft problems, with air spillage into the house since the house becomes the chimney. The air flow at the top of the chimney would account for the soot stains at the top. Notice how the stains are heaviest on the side opposite the ridge of the roof.

    The lower staining has me stumped, but wishing I was there to further investigate. Very interesting!


  8. #8
    Join Date
    Mar 2007
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    Near Philly, Pa.
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    Cool Re: Can't explain BPM

    I'm not a big fan of those large multi-flue covers. They tend to trap gases where they can shunt back down the other flue in chimneys with multiple flues. On single flue chimneys, they aren't necessary and make servicing and inspection more difficult. Also, more money. From the stains at the top, I would focus on the prevailing wind direction if it is front to back or not, which would explain the directional stain. I agree with Jim G. there is probably more to this story. Also, if these are not ceramic vented logs, I would want to know why they are producing so much gunk/ BPM.

    BTW, Dave, I use BPM indoors primarily. Outdoors, if I see it on a direct vent termination or siding adjoining, I usually refer to it as BPM. However, when they have washed the siding or no particles can be wiped off, I refer to it as a "stain". Still, it is good to see so many picking up on the lingo.

    As for that side stain, being somewhat sheltered, I would suspect it is algae w/ dirt and BPM and I'll bet this is facing somewhat northerly. The point is, it may have nothing to do with the stuff up top.

    Bob

    Keep the fire in the fireplace.

  9. #9
    Join Date
    Mar 2007
    Location
    Charlotte, NC
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    Default Re: Can't explain BPM

    Thanks guys.

    While I know I haven't used the "BPM" phraseology excessively, or too often for that matter, I'll tone it down on findings like this.

    Now where's my dog?

    Come, Stain !


  10. #10
    Join Date
    Mar 2007
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    South-West Michigan
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    Post Re: Can't explain BPM

    If it's mildew, it's not particulate matter, it's organic. Any way, it would be helpful to know the directional orientation of the chimney. These black stains could be two different things. Has any body tried cleaning them off? Do they come back? If it's soot, then it would be fire related. Was the flue cleaned before the gas log install? How complete is the combustion of the gas log (is it rated?). More investigation is needed.

    Randall Aldering GHI BAOM MSM
    Housesmithe Inspection
    www.housesmithe.com

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