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  1. #1

    oil furnace interior wall penetration

    I recently bought a house, and have started refinishing the basement and as I do this I realize that there is a problem with the furnace flue pipe and clearances to combustibles. I realize this is not up to code, and needs to be fixed ASAP. Previously the condition was the same as pictured but with wood paneling TOUCHING the flue pipe. It's been like this for 20+ years from what I understand. Inspector didn't mention this issue. I started putting up drywall but have not stopped now realizing I need to address this.

    This is an oil furnace, 6" single wall pipe, penetrates an interior wall from furnace room with a thimble, before making a short run in the finished space and then a 90 degree turn stubbing into a masonry chimney.

    If I understand correctly, penetrations of interior walls are not allowed, period, even with dura-vent or similar.

    I'm going to get a contractor out here soon to deal with this, but I wanted to see if anyone here had any suggestions. Do I need to box this corner out, so that it remains part of the furnace room? If so, how much clearance do I need both to the interior masonry and to the boxed out partition, assuming I use cement board on the back side? Can I just build a soffit around it instead with an access door for inspection? Thanks in advance for any advice.

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  2. #2
    Join Date
    Sep 2002
    Location
    Northeast Ohio
    Posts
    4,842
    Boxing out the corner is about the only way I see. I would defer to you local inspection authority with regard to clearances as these can vary by jurisdiction.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  3. #3
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,003
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  4. #4
    Join Date
    Dec 2004
    Location
    Caledonia WI
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    881
    Can you see the chimney from the furnace room? If so maybe it can be accessed from there with new hole. Anyway it is done it will to have good access for servicing.

  5. #5
    Join Date
    Aug 2001
    Location
    Pavilion, NY
    Posts
    2,123
    Do you need a corner book shelf?
    ...

  6. #6
    Quote Originally Posted by billg View Post
    Can you see the chimney from the furnace room? If so maybe it can be accessed from there with new hole. Anyway it is done it will to have good access for servicing.
    unfortunately, no. The wall on the right where it elbows into the chimney is drywall on furring strips right on the foundation.

    I'd love to do an (inverted?) bookshelf or something like that that doesn't run to the floor, I was just concerned about access. I think furnace service guy needs to be able to pull that elbow out to look into the bottom of the chimney and cleanout. maybe a large soffit with a large non-flammable access door large enough to pull the elbow out?

    Who would I call to do this work, a chimney sweep or a GC?

  7. #7
    heres the view from the furnace room side

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  8. #8
    Join Date
    May 2012
    Location
    Upper Michigan
    Posts
    3,588
    When that chimney needs a cleaning or the vent pipe is hate to be the guy getting soot all over a finished room lol

  9. #9
    Join Date
    Aug 2001
    Location
    Pavilion, NY
    Posts
    2,123
    Vent pipe also reduces in size off the top of the boiler.. Typically a no no
    ...

  10. #10
    Join Date
    Aug 2012
    Location
    North Dakota
    Posts
    518
    loooks like that wall should have bee 1' further out ???

  11. #11
    Quote Originally Posted by mechanical'al View Post
    loooks like that wall should have bee 1' further out ???
    Yes but that would be too easy. It's a structural wall right at mid span following the roof peak. Furnace room should have been on the other side!

  12. #12
    Join Date
    Aug 2004
    Location
    S.E. Pa
    Posts
    6,166
    You must maintain a 2" clearance to combustibles off the chimney. Therefore the drywall and furring strips would have to be cut back. Otherwise, you could install a listed chimney liner to avoid that clearance issue.

    Single walled chimney connector for oil carries an 18" clearance to combustibles. That means in addition to the combustible wall penetration you have to cut the drywall and furring back from the chimney breaching 18" around the breaching hole.

    The chimney does not have a cleanout as required by code. The listed liner can negate this requirement.

    The connector can not insert into the chimney breaching unless it is stainless steel. The liner would take care of this issue.

    To penetrate the combustible wall, use listed 'L' vent, which carries a 9" clearance to combustibles.

    The connector must be the same size as the appliance collar or larger. It can be downsized one diameter right at the chimney only.

    That tee for the barometric damper looks very sloppy. Replace it with a factory made tee and place it closer to the appliance--within 1.5 duct diameters of the appliance collar if possible.

    Pipe must pitch up 1/4" per foot. Min. 3 screws per joint. Support horizontal offsets and elbows.

    Being enclosed, measure for adequate makeup air: min. 50 cubic feet of room per 1,000 BTU input.

  13. #13
    I went to the building department, they only care about clearances to combustibles. They said I could replace with 2" clearance insulated pipe and leave it as is as long as its 2" from any studs, and wall penetration is ok.

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