Hello I am new to this site. I am retired, but pass time doing handyman work. My question is My vent that travels straight up 16 feet between 2 toilets, has a very bad odor, I have flushed it with water, poured bleach down it, and it still emits an odor which comes in the house if the wind is in a certain direction. I have been in the home for 3 years, and it has not changed. My veny is 3" in diamater. Do they make a auto vent I can install on the top of the vent and if so where can I buy one. All help appreciated. Don

Do they make a auto vent I can install on the top of the vent and if so where can I buy one."

They sure do Don. It's called a "Odor Hog" and you can check them out at; http://odorhog.ca/iw_faq.php
Good luck, Tom