We have an ejector pump in the basement and the venting pipe comes out of the basement concrete wall and goes up the outside of the house.
In winter, this smells every morning, there seems to be a negative pressure/stack effect in the house as the chimney is also on the outside wall and a draft comes in.
As soon as spring comes round/summer, the basin smell stops so it seems like the venting works correctly again even with all doors closed.
Is it possible that having the pipe on the outside would prevent venting from happening? Was wondering of the pipe should be relocated on the inside walls and go out the roof?
Are there any other ways to solve this venting issue?

 

Do you have forced air heat? If so you might smell it when the burner exhaust fan and blower are running in the winter as it may be causing negative pressure in the house. That negative pressure could be sucking in the gases and odors.

- Peter

 

nope, electric baseboard heaters and occasionally the fireplace is on but only weekends7

 

IMO, you are correct it is a stack effect issue and moving the pipe to the inside where it will be warmer should resolve the problem.

Bud

 

How do you cut a hole for a pipe in a metal roof? Just drill through from an access point in the attic?

 

Would there not be a stack effect on the little part of the venting that sticks out the roof? Also, how do you stop snow getting in and blocking up the vent? The roof often has a lot of snow on top in winter...

There is a difference though. Stack effect in a chimney occurs because there's a big hole for the air to come out of. The vent pipe is only 2" Anna goes directly into a sealed sump/ejector pit.