In previous winters, usually once or twice during the season, an ice cap forms on the top of the vent stack and there is a sewer gas smell in our house. I then go up on the roof and chip the ice off and the smell goes away. Going on a snow and ice covered roof is scary and something I would like to avoid. I insulated the vent stack in the attic hoping that this would keep the air in the stack warmer until it vented out the top, but the problem still remains. Our house was built in 1994.
Answer:
Try getting a T fitting for the top of the stack and it should turn with the wind. If a big box store doesn't have one, a plumber might.
