Hey guys, saw holes drilled in a return ( about 50 of them ) right at the unit in a basement, code I believe says you cant have any openings in a return within ten foot of the unit as it can pull combustion gases into the dwelling, is that true with a enclosed chamber that draws combustion air from the outside ? I wrote it up and the answer was to draw moisture out of the basement. I also wrote it up as the ducts may not have been figured correctly and they needed more warm air for the air handler. What are your thoughts thank you. Also what is the pitch on a gas water heater exhaust.
Ron the pitch on a exhaust flue is 1/4 inch per foot. As for the holes in the return air, pics would be great you did not give the size of the holes and no it is not possible to draw CO from a sealed furnace as to the exhaust side but were the burner enclosed also or were they open.
Best engineering practice is not to draw any return air from a non-conditioned space. Personally I would not want any old damp mold potential air circulating through out my living space. I don’t follow your thoughts on the statement I high lighted in your post did the basement have supply air ducts provided.