So I have been an associate member of ASHI as well but their boards are not as active so I stayed here. (not to mention they don’t offer any kind of help to inspectors like NACHI does)
Well they have an associate corner where they post pictures and ask us pathetic worthless associates if we can find the problems. I decided to take a few stabs. The picture is not clear so its not worth posting but it was of a gas water heater vent. The vent peices were installed backwards so I noted it. Here was the response.
"I would argue otherwise. The direction of the joint will have no effect whatsoever on whether or not combustion gases enter the house. The vent is supposed to be under negative pressure while it’s venting, so any leaks will be from the outside in. Even if it were under positive pressure, leaks would occur no matter which direction the pipes were pointing.
There is an advantage in having the male fitting on top. It keeps condensation inside the vent pipe until it gets to the bottom. Look at a piece of B-vent. The liner has the male end on top and the female on the bottom for precisely this reason. "
I had never heard that before. Is this true?