I have a two story house built in 1914. It has a bathroom on each floor right above the other using a shared stack pipe / vent (our only vent pipe). In the basement we have a bell floor drain that I keep vegetable oil in.
Periodically when the second floor toilet is flushed, we get a sewer smell both in the downstairs bathroom and in the basement.
A few years ago, we found that a section of our stack pipe was cracked and had our plumber replace it.
Are there any cleaners would anyone recommend for putting down the drains? Down the main stack? Maintenance that I could do that would help eliminate the problem?
I’m thinking our lone vent is a big problem. Would the installation of an AAV help?