Originally Posted by Mopar1973Man
I also wondered why there was a pipe stub with a threaded top (female) under the kitchen counter pointed straight up. Do I have to get a vent or could I just put a cap in the hole?
Mopar, Check out Batman_777 's previous post on this thread. Trailers and RVs sometimes have this vent set up. The valve that he has pictured screws into the female thread you were talking about. This is a flapper type assembly and is readily available at any Lowes, Home Depot or plumbing supply store. Don't plug the line or you'll have a drainage problem in the sink that it services, use the pictured assembly it acts as a vent and a plug.