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Can I run the flue vent pipe thru interior wall?

sebobin Member Posts: 1
We're remodeling our basement. Existing flue vent pipe goes into chimney about 4' from oil boiler/burner. We want to put a wall between the oil boiler/burner and where the flue vent pipe enters the chimney. We're in CT. From what I can find online, I'd need 18" clearance between vent pipe and wall (combustibles) The existing pipe is single wall sheet metal. I read somewhere that if I use double-walled pipe, the clearance is 9" Can I use fire-rated Sheetrock to reduce the clearance? Are there sleeves that can go over the vent pipe to reduce the clearance. Any other options? Thanks!


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,237
    Depends, but drywall is combustible. See if this helps
  • ChrisJ
    ChrisJ Member Posts: 14,941
    edited December 2016
    Best thing I can think of is if you used something like is used on wood stoves to pass through a ceiling.

    Might be expensive though, I think you need triple wall pipe for that small area. A B-vent only needs 1" clearance but you cannot use that with oil so I think you may be stuck with a type A vent.

    This is certainly not my area of expertise and I'd recommend contacting the manufacturer of such a product. If it can be used horizontally etc.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • BBros
    BBros Member Posts: 41
    Check with metalbestos type manufacturers. Even the type-A have very small clearances to combustibles, like just a couple inches. They make various flanges to deal with this. I've only ever gone through floors with it, but I don't know why a wall would be different.
  • Jamie Hall
    Jamie Hall Member Posts: 21,519
    Also check with both your homeowner's insurance company and the local AHJ -- fire marshal or building inspector, usually. Whether we like it or not, they sometimes have their own thoughts...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Bob Harper
    Bob Harper Member Posts: 983
    You can do this if you use type L vent, which is listed to UL 641 for oil. You'd need a listed 'pass-through'. Enclosing the boiler may violate the makeup air requirements. You'd also need a service switch where you enter that room, a switched service light over the boiler, and a grounded 120vac outlet not to mention a Firomatic valve at the boiler. The chimney would need to be relined if not already done so and include a cleanout. Get a sweep to perform a level II inspection with video scan.