I have an in-wall laundry drain - pictured below.
Since we moved in it had a significant clog which I unclogged with a combination of wet-vac sucking on the drain and snaking the vent pipe. Finally we got it to drain without flooding but now there's an awful sewer smell after doing laundry. Before unclogging, while it did flood fairly quickly, there was no sewer smell
So my questions are:
- How can I determine if the sewer smell is from a lack of p-trap in the wall (ideally without removing drywall)?
- Could the sewer smell come from another clog?
- Whether or not there is a p-trap in the wall, could I just put a p-trap outside of the wall attached to the plate to solve the smell?