On Thu, 03 Mar 2005 18:10:23 GMT, "Joseph Meehan"
wrote:

I've never seen one (the flapper part) that would work well for
vertical application, however.

I really don't know as I have no experience with that set up, all mine
have been out the side.

I was going to have to do this sooner or later anyway, so I Googled:
"dryer vent" vertical cap
There are all kinds. Here's one: http://www.cjmetals.com/vents.htm