Two vents for grey tank?

[Poolman]

I am in process of refurbing 1983 Excella 31' rear bath.

I demo'ed most of the bath today in advance of new pex plumbing and a new floor plan for bathroom. I noticed that there is a vent line coming off of the grey tank (just above the tee for the sink drain) that T's again to connect to the black tank vent. This "combo" vent runs around to the curbside and disappears behind the shower wall. Additionally, directly off the grey tank in a secondary location, there is another vent line that also runs behind the shower. I assume that the two vent lines join together somewhere behind the shower wall before entering the wardrobe and exiting to the roof.

Since I will be modifying the plumbing to some degree, is there a need for the two grey water vents?

[Poolman]

If anybody has some insight, here is a pic of what I have.

[Glenritas]

The vertical pipes are vents for the sink , black tank and bath tub on our '69 Tradewind. They all connect in the corner and exit as 1 out the roof.


The horizontal pipes are the drain lines. They plus the kitchen sink lines all end at the dump valve. The kitchen sink has its own vent pipe.

Our trailer didn't have a gray tank.

The way they ran the drain and vent lines one would think they owned stock in the ABS industry

The last pic is what is looked like last month. Our new shower is going in the street side corner. It partially blocks the window.

I've run all new PEX and moved the battery and charger, added extra wiring from the new inlet. But that's another story.

I hope the pic's give you some insight on what you may have.

[Poolman]

Thank you! That does help.

Looks like a bunch of redundancy in yours much like mine. Like you said, Airstream must own ABS stock

I guess it was an easy way to get the black tank vent tied in, but wonder why not just tee it in to the first grey vent instead of running two behind the shower wall? Just thinking about a more efficient, cleaner way to redo this mess.

Thanks for the pics.

[Glenritas]

When I install my wet shower ,it has the black tank molded in, I will run a vent up and then across the rear of the trailer just above the PEX lines to the existing vent stack in the curb side corner.

I'll also tie into it the vent for the sink and shower vents .

The drain line will go to the forward mounted gray tank will serve the bath sink, shower, kitchen sink and washing machine.

Hmm ... sounds like I should buy some ABS stock

[HiHoAgRV]

The vent in the sink drain line is to allow the sink to flow without burping. When the P trap is full there is air in the drain after the trap and before the tank. Pouring watering the sink builds up pressure on the P trap until it burps and allows water to flow. Think of the vent as a drain line vent, not really a gray tank vent.

[Poolman]

Thanks HiHo. That makes more sense! It doesnt look like a replumb of the vent lines will save much space, so probably leave it as is.

[youngpeck]

See post #13 on this very subject on this thread:

http://www.airforums.com/forums/f162...ml#post1578682