I own a two story modular home in western MA with a fireplace in the living room. Every time we have a fire the hall outside the living room heading into the kitchen and the kitchen itself smell like a lead from the septic system. I would send you a floor plan but I can find no info on this house at the manufacture's web site. Its a home built in 1999. It's a 4 bedroom 21/2 bath with the master bed downstairs. Septic tank and field is out front with the septic vent pipe running from the basement up through the wall between the living room and kitchen, adjacent to the pantry in the kitchen. This wall in the pantry is especially "aromatic" when the fire is going. I'm suspecting some sort of back-draft of something from the heat in the chimney - but it all doesn't really make sense to me. The original owners were a couple with one young daughter. We are only two adults. There are no other signs of septic blockage or impending overflow. Have you ever heard of similar problems and is there anything that can be done to eliminate the odor?
Answer:
What you're telling me is that the plumbing stack going up through that wall has a glued joint in it that is not properly glued (if it ever was). It is quite common in cases like this for the tradesman to take a shortcut and not glue joints in breather pipes. This means that as you heat the wall, the joint piece of the stack does not heat up as readily as the pipe itself and with the joint not being glued, sewer gasses escape. These gasses, like any other gas, fill whatever container (wall cavity)they're in and then escape by whatever means they can.