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G2407.6.2 (304.6.2) One-Permanent-Opening Method

Bernard Sobieski

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Joined
Aug 28, 2020
Messages
1
Location
Colorado
Hello,
Can anyone out there help me determine if there are additional requirements or constraints on the location of a permanent opening for combustion air in the IRC section G2407.6.2 (304.6.2)? My mechanical room is in a basement partially below grade, and I can run a horizontal duct out the top of the wall but the centerline of the vent will only be ~12" above grade. Not ideal, but would this break any codes for combustion air intake into a residential mechanical room with a gas hot water heater and furnace.
Thanks,
Bernard
 

ICE

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Jun 23, 2011
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9,098
Location
California concrete jungle
Oddly enough, I didn't find a prohibition in California codes. We didn't adopt the mechanical portion of the IRC so there may be something there. Considering that it snows in Colorado I would think that placing a combustion air opening should take that into consideration.
 
Last edited:

cda

Sawhorse
Joined
Oct 19, 2009
Messages
18,672
Location
Basement
No section references



  • Intakes must not be located where they might be obstructed by drifting snow (consult local experience as to the height of snow drifts against buildings).
  • Intakes must not be located within a zone of significant ground-level dust and debris generation (e.g. mowing, leaf blower use). At a minimum, intakes should be 2 feet above grade.
  • Intakes must not be allowed to be obscured or hidden by vegetation. Vegetation must not be allowed to grow within 3 feet of a ventilation system intake.
 

ICE

Moderator
Joined
Jun 23, 2011
Messages
9,098
Location
California concrete jungle
No section references



  • Intakes must not be located where they might be obstructed by drifting snow (consult local experience as to the height of snow drifts against buildings).
  • Intakes must not be located within a zone of significant ground-level dust and debris generation (e.g. mowing, leaf blower use). At a minimum, intakes should be 2 feet above grade.
  • Intakes must not be allowed to be obscured or hidden by vegetation. Vegetation must not be allowed to grow within 3 feet of a ventilation system intake.
Where did this come from? Combustion air openings are different than ventilation intakes.
 

cda

Sawhorse
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Oct 19, 2009
Messages
18,672
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Basement
Wide Wide world of internet

Al said it was correct
 
Last edited:

klarenbeek

Silver Member
Joined
Jan 28, 2010
Messages
216
Location
Sioux Falls, SD
G2407.11 (304.11) Item 8 requires the bottom of the opening to be a minimum of 12" above grade. Beyond that, it depends if you interpret a combustion air inlet that's open to the mechanical room as a "gravity outdoor air inlet". R303.5.1 would then require it to be a minimum of 10' from hazardous or noxious contaminants.
 
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