[Porsche-O-Phile]

Shouldn't be a problem - as said the issue is typically galvanic action when dissimilar metals (iron/copper) are used.

Keep in mind that if any PVC is being used for the vent pipe portion extending above the roof line that PVC does get deteriorated over time by UV exposure. For this reason you may want to consider a protective finish coat/paint, cladding it or sleeving it, or ensure that you can yank the weathered portion out and plug a new one in easily every few years (would require re-flashing) - make the connection below the roof simple and easy to get at so you don't have to bust half the roof or ceiling apart to get at it. Or just use black pipe for the portions above the roof. A rubber connector is a good idea, it will also create a thermal break (iron/metal will conduct heat) so put the fitting reasonably close to the underside of the roof deck and/or insulate the exposed portion below the roof.


An access panel might make sense if you can stick one in a closet or other non-obtrusive location so you can access, undo the connection from inside, go up on the roof, yank the old one out, plug the new one in, reflash and go back inside to connect it up.