Plumbing Vent

Every tank needs to be vented to allow air to exit and enter when the fluid level changes. Our Avion will has two grey tanks connected end to end placed under the floor, but no black tank. The black tank is replaced by the cassette toilet. The fresh-water tank also needs to be vented, but that is a separate system.

Usually grey tanks are vented with 1-1/2″ ABS or PVC pipe, but to simplify running the vent in confined spaces we’re going to use 1″ plastic tubing. Originally there were two roof vents for the plumbing system. We’re going to combine those into one roof vent.

We’re not reusing the original vents because there are vents available with a lower profile, and the originals were steel. We’re using the Aluminum Roof Vent Pipe Cover – Vintage Style from Vintage Trailer Supply. Here’s what it looks like installed. We put it as close as possible to the solar panels so there’s only a slight curve under it. You can see the reflection of the solar panel, which was angled up to make installation easier. This vent is designed for use on Airstream trailers and has a slight curve in the base to fit a curved roof.

This vent comes with a rubber gasket that has a hole in it sized to be stretched over a 1-1/2″ pipe. Since we’re using flexible 1″ tubing we installed a poly fitting into a threaded plate which was riveted to the inside of the skin. Rivnuts were then installed for the six bolts that will hold the vent cover. Scews could also be used, but bolts in rivnuts are easier to seal and there’s much less chance of the hole stripping out which is common with the thin skin aluminum.

The vent is to the curb side of the solar panels and over the rear of the bed. The tube will be routed to the fitting through a cupboard.