Can anyone share their narrative for when the HVAC system is conditioning an attached garage?
Was it equipped with a fire damper?
Also, from the “Search” function above":
R309.1.1 Duct penetration. Ducts in the garage and ducts
penetrating the walls or ceilings separating the dwelling from
the garage shall be constructed of a minimum No. 26 gage
(0.48 mm) sheet steel or other approved material and shall have
no openings into the garage.
Commentary: Ducts are permitted to penetrate the required separation
(see Section R309.2) between the garage and the
dwelling unit when the ducts within the garage and the
portion of the duct penetrating the wall are of No. 26
gage (0.48 mm) sheet steel or other materials acceptable
to the building official. Steel ducts are required to
help prevent the passage of an undetected fire within
the garage to the dwelling unit. See Commentary Figure
R309.1.1. The opening limitation in the garage is to
limit the path for smoke to enter the dwelling unit.
there is no return air in the garage.
I found it thanks
IRC Section M1601.6- HVAC systems that supply air to the garage shall not supply or obtain air from any other space but the garage. HVAC systems that supply air to the living space shall not supply or obtain air from any other space but the living space.
Essentially the same system cannot condition both the garage and living space right?
Yes. That’s what you needed.
Supply vent in return air plenum in garage. This may allow harmful exhaust fumes from automobiles to enter the ductwork and be discharged into the living area. Recommend removal.
The above applies to ducts passing through the garage ie in one side out the other, such as heating a room over an attached garage. Like the others said, a garage and living space can not be in the same conditioned space because of the exhaust fumes etc…