Eliminating Galley Plumbing Vent?

[VanIsle]

Hey all!

First time poster, been really enjoying the myriad of info available about airstream trailers on here. I am fixing up a 1975 31’ Soverign and I have a question about the “galley” plumbing vent. My limited understanding is that it’s the vent stack for the grey water tank and I’m wondering if anyone has experience with possibilities of eliminating it?

The previous owner built a whole shelf and drawer system around the vent during a previous Reno but I had to tear it all out to address a leak that was coming down between the panels behind it. Needless to say, now the vent is in the middle of the hallway... I mean not really but what are my options here? I’d rather not need to build a whole cabinet to conceal it and since they are such a terrible spot for leaks to prop up I wondered also about turning it straight 90 degrees back toward the wall and then up a foot or two with a cheater vent (also sometimes called an auto vent) on it?

Any insight would be so appreciated!

Best,

Tanner

[richard5933]

If it's the vent for the tank intended to expel gases produced by the gray water in the tank, then you'll need to have it vent to somewhere.

Those cheater vents, like a Studor vent, are one-way check valves which let air in but not out. They are designed to be used next to a sink or other plumbing fixture to allow the drain system to pull air in and provide for good drainage, but they won't let sewer gas escape.

If you want it moved out of the center aisle, perhaps you can re-route the vent inside the floor so that it comes up against the outside wall, and then have it follow the outside wall up to the exit point on the roof. It's not that difficult to get one to seal so that it is leak free on the roof, but they do require periodic maintenance to keep them leak free. The waste tank will 'breath' through this vent and release sewer gases, so you don't want the exit point low and anywhere near noses.

[Minno]

On our '72, ours was in the wall, so you could definitely route it that way. When we renovated, we ganged our grey and black vents together, so we now only have 1 vent stack. It's worked well for 10 years, so far.


Kay

[Wazbro]

You also need a lot of air to enter the tank so it can dump properly.

I know with PVC you can use a heat gun to bend it to follow the wall, I haven't tried it on ABS.

[Bill M.]

Our grey water really stinks after a few days.

[fiftysafari]

I am in the process of renovating my 1954 Safari.
I plan to vent my grey water tank through the wall.
As has been stated, an open vent is necessary to allow air to enter the waste tank when the tank is drained.

[Boom]

X2 to what Minno posted. On our '71 we added a gray tank. The black and gray both use the same single roof vent. We used 1-1/4" flexible pvc pipe and installed it inside the wall between the inner and outer skin.

[VanIsle]

Thank you so much for all your responses. That makes sense, I knew it would draw air in when the tank was emptied but I wasn’t sure about it needing to “breathe”. Now I’ll have to consider the beat way forward with it as it seems like the tank is right below the flooring so even a short 90 would still bring me up above floor grade.
I might just bright it straight back to the wall and come up and in rather than the Willy Nilly way that it comes up and goes through the roof.
Thanks for the idea about bending PVC, I’ve heard and seen that you could do that with ABS as well but I don’t think I’d gain too much by doing that.
Building a box to cover the pipe on the wall could be a bit interesting following the curve so I’ll have to think about how to conceal it.

Thanks again for all your input I really appreciate it!

Best,

VanIsle

[fiftysafari]

If I may tag in to this discussion...I plan to vent my new grey water tank through the wall of my Safari using the existing hole for the old manual water fill fitting.

The existing opening in the side of my Safari is below the window level and I am hearing comments about how bad a grey water tank can smell.
Is smell a big problem from the vent?

[richard5933]

An option for you is to drop the tank and move the location of where the vent tube leaves the tank. There are multiple ways to patch the hole from the current vent in the tank and to add a new one, the best probably to do so with spin-weld fittings. Likely there is another place in the top of the tank which will line up with an interior partition and which would allow you to vent straight up through the roof. A bit more work, but with all that you're doing there is no reason to not do this right.

Not sure if it helps at all on this conversation, but on my 1974 Custom Coach bus conversion, the factory vented the waste tank with a 1/2" line. It exits the top of the tank, and then it take a 180-degree turn and leaves the coach through the floor of the basement where the tank is. The bottom of the 1/2" line below the floor is cut at a 45-degree angle with the slope pointing towards the rear, creating a low-pressure area at the end of the line when the coach is in motion to prevent gases from being pushing back through the plumbing.

This is on the road side of the coach. We never have issues with odor from this vent, and we've never had issues with the vent being too small for proper function of the tank (not on filling while using, not on dumping).

If I were to do any work on this system, I might consider going up to 3/4" plumbing on the vent. But, in truth I don't see any need to do anything since the system works. The only maintenance I have done on this is to check for any critter nests in the end of the tube.

My point with this is not to recommend you vent your tank through the belly pan. But I did want to mention that there is more than one way to get things working and that some situations require creative thinking.

[Minno]

Our vent stack runs up inside the outside wall of the trailer. Plumbing to get it there is hidden inside cabinetry since the grey water tanks (2 tanks ganged together) are under the floor in the kitchen area. Sometimes it takes a little creative finagling to get things where they are hidden the best.

I would not vent the grey or black tank through the wall low down on the trailer. They do stink after awhile, and you will get that blow back into the trailer. Through the roof, there's no smell that gets back into the trailer if it's working properly.



Kay

[LLninja]

I’m renovating a 1966 Tradewind and was thinking about eliminating a couple vents also, but maybe I’ll need to look at this cheater vent mentioned in the 1st response above. We are contemplating eliminating the black tank, going with a composing toilet, then replacing the black tank with a gray tank as our trailer doesn’t currently have one.

Thank you so much for the studor vent idea.

[StevenD]

Since this is a grey tank vent, the tank will also have inlets from your kitchen and bathroom sink discharge. You could cap that existing vent line and and tee a vent line off of one of those sink drain lines if they will be located somewhere close to that roof vent cap. This is sometimes referred to as a wet vent.

[LLninja]

Originally Posted by StevenD

Since this is a grey tank vent, the tank will also have inlets from your kitchen and bathroom sink discharge. You could cap that existing vent line and and tee a vent line off of one of those sink drain lines if they will be located somewhere close to that roof vent cap. This is sometimes referred to as a wet vent.

The vent to the future gray tank isn’t the issue, it’s the vent to the shower which has an unsightly cover right in the shower area and the vent to the galley sink which was covered behind a wall that we are removing and opening up that are the issues. Or are you saying we could potentially eliminate all 3 vent pipes and use only Studor vents throughout? i thought I needed to have at least one real vent.

[richard5933]

Both black and gray tanks will produce sewer gases. These need to be vented to somewhere. Studor vents serve to let air into the system so that the drains will drain properly, but they are designed to prevent sewer gases from escaping.

If you don't have a vent on your tank(s) to let sewer gases escape, they'll find their way out. Probably won't do it in a way which pleases you.

The tank should be vented.

Through the roof is the usual way since it carries the odor up high and keeps it from being an issue in a campsite. There are other ways though, such as my vintage coach which vents both the black and gray tanks through a narrow vinyl tube down through the floor of the storage bay they're in. It's worked since 1974 and rarely produces any issues with odor. But if the wind is just right...

[StevenD]

My understanding is that the best venting is done thru the roof, (although not perfect as critters can crawl down that pipe if there is no screen). Not sure about the use of the so called cheater vents but they seem to be commonly used in box travel trailers to lower costs and I have read about stinky problems when that check valve gets stuck open. Real issue is if your tanks are not adequately vented, when you drain them, they will drain slower and suck the water out of your sink and shower traps, thus allowing sewers gasses into the trailer.

[LLninja]

Thanks, this all makes sense now. I’ll keep the vent to the tank, add studors to the galley and lavatory/shower drains, then replace the studors if we start to smell stuff.