The complaint that I have is the odor that is in my basement only on cool mornings and sometimes at bedtime. And what really upsets me is that I never had this problem before the plumber who is licensed put in the trap and the vent. I read the above answer to my question and the other post suggested and went to Home Depot today and bought a 5 ft. pipe (which I hope is long enough) and connector to try to bring up the level of the outside vent. I figured that would be cheaper and less work than digging up my basement floor, which the plumber suggested I do. Not being a plumber by NO stretch of the word, it only stands to reason that it has to do with the outside vent being this only happens with cooler weather. I am open to any other suggestions too. I appreciate any response because it just doesn’t make sense to me. Thanks!