I have an air vent in a wall in one of my downstairs rooms. Behind the vent is a Studor vent. On the other side of the wall is a small bathroom.
About a year ago this room started having a smell like the one that occurs if no one has been living in a house for sometime, but more acute. I've tracked it with my nose to this vent.
Any ideas what it might be? I don't think it smells musty... It's like someone ground up drywall.