We live in a log home in Northern MN. Our sewer vent pipe freezes over regularly. We have cut it shorter, as short as we can without it regularly getting covered with snow, and wrapped heating tape around it in the attic up to the roofline. My husband wants to put what he calls a "gooseneck" pvc top on it. I assume so it will curve over and down preventing snow from getting in it. I think the warm air will hit the top and form ice anyway. I would like to put a cover of some kind on. Not blocking the airflow but a little tent. We have been struggling with this for over a decade and I am really tired of waking up with headaches. I know it can be a very dangerous situation.
What do you think?
Haz

Sounds like a Arctic Vent,(see image) is just what you need. Check them out at '; Water Line Heat Trace Freeze Protection For Cottage, Home, Commercial Water Pipe Applications - Arctic Vent (http://www.heatline.com/arcticprod.htm)
Good luck, Tom

Thanks. That looks like an option. Which of the two that I asked about do you think we could try, or do you think neither would be worth the effort?

I would like to put a cover of some kind on. Not blocking the airflow but a little tent.
You're talking about a vent cap,(see image) Most plumbing shops should carry them. If you install a Arctic Vent plus a vent cap plus all the other stuff you've done that you've just about covered all bases. Good luck and stay warm, Tom

In addition to Tom's excellent advice...

Less expensive option I have found helpful in your situation is to take an electric blanket, wrap it around the pipe in the attic, secure it with tape. Plug it in at low setting. Put it on timer. Leave it ON through out the winter.

Thank you Tom
Milo, we have heat tape around the pipe in the attic. It's helped but not eliminated the problem. Thanks all
HAZ

I don't know if heat tape generates enough heat to keep it from freezing...