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

[Bernard Sobieski]

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]

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.

 

[cda]

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]

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]

Wide Wide world of internet

Al said it was correct

 

[klarenbeek]

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.