Wow!!! Is this a new construction? How could someone be so stupid to stick an air return in the garage where carbon monoxide is created? There’s no way that a board is going to 100% prevent a gas from seeping inside the air return and into the rest of the house.
IRC 2000 Section M1602.3 and 2003, Section M1602.2 Prohibited Sources
The prohibited sources section allows for permanent openings between rooms in order to connect spaces together to meet a return-air location requirement: Item 4 prohibits return-air sources as follows: “A closet, bathroom, toilet room, kitchen, garage, mechanical room, furnace room or other dwelling unit.” Item 5 prohibits “A room or space containing a fuel-burning appliance where such a room serves as the sole source of return air.”
Are you sure it wasnt an attic access. I saw something similar once and until I looked closely, I didn’t realize it was an attic access for the garage. It seems that Harry Homeowner cut the hole to make an access for storage and used the grille to hold up the piece he had cut out. What will they think of next?
No, this was not new construction, unit was built in 1991, and as they say 'a little old lady had lived in the condo." Thanks for your response, last night I was so tired and couldn’t think straight I forgot I had another photo showing the intake on this vent.
Thanks again, now that I’m awake and thinking better . . . (well, won’t go there about thinking better) . . .
See attached photo . . . at least I was awake enough during the inspection to remove the grille and take out the board blocking, then got a piece of paper to see which way the air was moving and sure enough is was sucking in.
Thanks for your response, my first thought when I saw it was heating and cooling the garage (see that alot in my area with temperatures in the summer 110°F+), and my second was the attic access made by the homeowner. Deferring to an HVAC contractor to correct the problem.
Perhaps this was a model home, and the garage was used as a sales office? Last house like that I did had the return sealed properly. If only a plywood board is in the return with no sealant, CO and other fumes could leak around the board and into the home. I would write it up if not properly sealed off.