I've been noticing an occasional sewer smell in my bathroom, and finally realized it's only present when it's below freezing outside. As soon as the weather warms up, the smell goes away. For reference, my house was built in '55 and the toilet is plumbed into the original steel sewer line. There are no leaks (everything below the upstairs bathroom is easily accessible from the basement), and no issues flushing. House has sewer service, so no septic tank to worry about.
Could it just be the steel pipe contracting in the cold? If so, would replacing the wax seal address the issue?
Additionally, if that's plausible, would putting a space heater near the steel pipe help by warming it back up (temporary solution to address the smell). Basement is finished and conditioned, but I don't heat it for comfort unless we're spending time down there. I'll just deal with it being 60 degrees when I'm doing laundry.
If not, any other ideas? That's my only hypothesis, so hoping to get some feedback.
I've got no problem calling in a plumber and plan to do so, but I'd just like to have an idea of what I'm up against so I can set expectations for pricing and such.
Edit: Have ruled out dry drain traps. Current plan is to just let the plumber figure it out and hope for the best. Thanks for the suggestions.
With a picture.
Air always needs to get in for water to go out.
(Kinda like holding your finger at the end of a straw in a bowl of water doesn't allow water in or out of the straw)
If the top right vent (roof or wherever) is plugged by snow or ice and you drain somewhere else, it's likely the basin trap will get siphoned to allow air in the way.
It then doesn't block sewer gasses from getting back in that way.
Interesting.
My sinks, showers, dishwasher, etc all have a separate PVC sewer line and only the toilet still uses the original steel one. Both sewer lines, PVC and steel, exit the basement separately, but I don't know if they stay separate all the way to the sewer connection at the street or combine outside. Thanks previous owner /s.
That said, I'll have to check the vent configuration. I think there's only one vent and want to say it's shared between the two, but I have no idea. When I bought the house years ago, the inspector didn't make any notes about that, so I assumed it was all good.
Thanks for that diagram, btw. Will see how mine compares and hope the plumber doesn't just recommend ripping everything out and starting over xD
If a vent is lacking the are air admittance valves (AAV).
They're basically a one way vent for air that allows inside air to be used for venting the pipes but doesn't allow sewer gasses back up.
It wouldn't be my first choice as they eventually wear out, but certainly much cheaper than rippong stuff out of the walls.