Each winter(Minnesota), when the temp. goes to -15 to -20
the vents seem to freeze and a sewer smell gets into the house.
The upstairs bathroon seems the worse.
I have a septic system. The house and septic are 4 years old.
I have never had this problem in any other house I have owned.
How can I solve this problem?
berick ... I can understand your situation.
For example here it's been around 42 below with a howling wind which can be typical in the middle of winter.
My house is around 55 years old and it had the vent pipe penetration similar to the one shown in this picture.
It would always be buried under snow and freeze closed. I got tired of getting on ladder to climb on the roof and clear it out. I used all sorts of methods to unblock the ice.
Finally since it was becoming a pain to do and freezing my butt off I decided to extend the vent. With the warm moist gases that exit this pipe it collects ice and still becomes blocked as seen in this picture .... but at least it doesn't get buried and doesn't freeze until the extreme cold hits.
Shortly after extending the pipe I modified the vent from inside the attic space. If you notice there are two plumbing clean outs installed. One angles upward and one angles downward to accomodate inserting a rod to dislodge the ice at the top opening outside. The other is dislodge the ice blockage heading downward. While this is not a cure for the inevitable it's a method of clearing the problem safely and warmly.
Hope this helps.:)
Thanks for the information. Your vent pipe looks a lot bigger than mine.(diameter) Mine shows the same ice flow.
I appreciate the time you took to help me.