I bought my home brand new three years ago. Often a rotten egg smell comes through the heating vents mainly on the first floor. Because the smell was coming through the vents, I had expensive duct cleaning done last year; which didn’t solve the problem. It wasn’t until recently that I realized the smell was sewer gas. When my home was built, I had the developer to “rough in” plumbing for a full bath in the basement. The toilet pipe/drain has a cap on it whereas the shower drain was left open without a cover. (I put a large box over it for piece of mind)My question is, is the sewer gas that comes up through my vents coming from the plumbing I had installed?(It doesn’t really smell like sewer gas in the basement) If I complete the bathroom in the basement, would this awful smell go away?
By placing a box over an open drain you are just slowing down the entrance of sewer gas into your home. Apparently the trap for the shower rough is dry. Either cap the waste line off properly or make sure you continully have water in the trap to seal the sewer gas in the pipe. The sewer smell may well be coming through your furnace ductwork. Especially if there is a return air opening in the basement in the vacinity of the roughed bathroom.