[MaxwellD]

I purchased a “weather vane-type” cap for the top of the vent. That helped immensely. The ambient wind could be pushing tank gasses back down the vent (when you flush you get a pretty hefty odor). The weather vane helps to direct the flow of gases from the vent in the direction of the ambient wind outside. Easy installation but had to use pvc cement instead of the screws supplied.