First Trip & Grey Water Issue

[subfan1]

I also find it hard to believe that Airstream would have different methods of building a International vs a FlyingCloud. I would recommend that the service dept. use a camara like plummers use to find problems with sewer pipes in homes. This would remove the guess work of the vent tube too far down.

[65CV]

Here's what I think is happening:

You clarified the problem by saying that you are dumping a sink-full of water all at once. If the drawing is correct -- and I understand you properly, there is a lot of water where the word "Galley" is on your drawing. The fuller the sink, the more water pressure you have when you pull that drain plug.

When you pull the plug, you have a solid slug of water running down the drain. If that water pressure is greater than 0 psig at the Air Admittance Valve (the closest #6 to the galley on your drawing) it will not admit air to vent. The Air Admittance Valve only works when there is a vacuum -- kind of like a check valve that lets air in only.

Since you have a big slug of solid water coming down all at once, it rushes down in to the grey tank and doesn't let air out (See 11D on your drawing). If that entry point to the grey tank is flooded with rushing water, the only other escape route for the air being displaced from your grey tank is out your shower drain.

In my humble opinion, Airstream's fix is a patch. If it does work, it does so by restricting the water flow so that you don't flood the combination drain/vent line as it enters the grey tank. The best solution is to use a true vent, not an Air Admittance Valve. (11A should join 11H). On a finished trailer, you may not be able to do that. If my theory is correct, things would improve by lengthening 11A so that the Air Admittance Valve is above the height of the water in the sink, allowing it to work properly.

Good luck,

John

[bike_addict]

I have to say I agree with all of you. It didn't seem right to me either but when I talk to service all they tell me is that this is what Airstream says to do. They will not go above and beyond what AS tells them to do. And per the AS contact that they're talking to (which is who i talked to) this is what will fix it. It's worked before and this is what will fix it.

So I'm kind of stuck right now until I can get it back in my hands and show them them that it's not working yet. They are not open to another option until this one is proven not to work. I have not even been able to get a solid answer on if the vent pipe was completely checked.

Correct that valve was not designed to slow the water flow down but I'm told it's design does slightly restrict water flow.

I'm planning on going through it at the dealer and see that it's working before taking it off the lot.

I'll keep posting updates.

[bike_addict]

Originally Posted by 65CV

In my humble opinion, Airstream's fix is a patch.

This I completely agree with and was the basis of my argument at the dealer today. Instead of fixing the fact that the system cannot drain it's own capacity, they are trying to slow the water down.

[Ag&Au]

Until John (65CV) mentioned it, I didn't realize there was a diagram posted. I finally found it. I think I now understand the problem. As far as I am concerned it is a design flaw. It appears the only ways for the air to vent from the tank is either through the same pipe it is filling from or through the shower drain. If the water flow is sufficient to bar the air from escaping through the fill pipe it will build up enough pressure to force the water in the shower drain trap up into the shower. Once it has done this, it will continue to vent air into the shower until the inflow has diminished enough to allow venting up the fill pipe again. So it should not fill the shower pan until the tank begins to overflow. The problem could be occuring sooner because of an obstruction in the pipe labelled "11D".

This type of venting scheme works in a home because it is not flowing into a closed tank. In my opinion, they chose this method out of convenience without thinking it through. In my opinion it would be a lot better system if the tank was vented directly as the black water tank is done.

I am going to see if I can smooth talk customer service into sending the waste plumbing diagram for our trailer. I am curious to see if it is the same.

Ken

[bike_addict]

Originally Posted by w7ts

As far as I am concerned it is a design flaw....In my opinion, they chose this method out of convenience without thinking it through. In my opinion it would be a lot better system if the tank was vented directly as the black water tank is done.
Ken

Completely agree. And before seeing the diagram I was assuming it did have a separate direct vent like the black tank.

And while I understand Airstream's logic and I feel a little bit better since you understand it as well, I still have a hard time swallowing it. Granted I am by no means a very experienced RV owner nor am I very experienced with plumbing in general and I am more than willing to admit that. It just seems hard to believe to me that the pressure in the tank would be such that it would not allow the water to overtake the air and allow the air to escape.

I would love to see a mockup of the plumbing system with clear pipes so that I can see the water suspended in the pipe, held up by air pressure in the tank. I'm assuming you would see small bubbles of air moving through the water to the closest vent which would be the shower. As the bubbles hit the surface the water level would slightly drop.

[bike_addict]

Originally Posted by subfan1

I also find it hard to believe that Airstream would have different methods of building a International vs a FlyingCloud.

Turns out they're the same this floorplan, at least per this schematic. I'm assuming it varies per floor plan to accommodate the size and layout.

[Goal15]

We had issues with grey water in the shower when dumping a basin full of water in the galley sink. Talked to the PO and he said it happened once or twice to him, but he chalked it up to basically a plumbing scheme that was flat. We bought a stopper to put in the shower drain and haven't had a recurrence.

Hope they get this figured out properly both in the short term and in the long run.

[Crusty]

I forgot to mention that I always keep a rubber stopper in my shower drain so I don't get a pool in the shower when I drain the kitchen sinks. I always figured that it was due to a poorly flowing grey water system.

[bike_addict]

So I just had a bombshell dropped on me.

It's going to take a week to get the part in from Airstream.

How does this just now come up?

[Sphere Guy]

That sucks Ronnie, I feel for you. Could you order it and overnight it to the dealer? May be quicker.

AS long as you get your AS back for the Piney Woods Rally.

BTW, Do you know if Mill creek has wireless?

Sid

[Goal15]

Must be terribly frustrating.

Not to make light of the situation but tell them you want a loaner to use while they are putzing around with your trailer.

[65CV]

Ronnie-

Can't you use the trailer this weekend if you let the water out of your sink slowly? Use anything to restrict the flow out of your sink -- even your hand -- and you are effectively doing what Airstream will do with the new HepVo valve.
This will let you know if their idea will work.

One more idea for you, that is a bit more work:
I don't know what the plumbing inside a new trailer looks like but you may have an opportunity to prove or disprove the poor venting theory. You could remove the Air Admittance Valve, again the #6 item closest to your galley. Replace it with a fitting that you attach to a flexible piece of tubing (picture swimming pool hose or the like). Make sure that the other end of the flexible hose is open and is at least 3 feet above the level of water in the sink. Let the water out full force and see if you still have any issues in the shower. If not, you've proven that it is improper venting and that Airstream is attacking the symptom, not the cause of the problem.

John

[65CV]

Ken-

You are definitely correct that "The problem could be occuring sooner because of an obstruction in the pipe labelled "11D".

Don't you think that the problem could also occur because of flooding at the same location? If Ronnie is letting all the water out at once, the assumption of two phase flow could fail, leaving him with a choked vent. Worse yet, a bit of a Venturi effect.

John

[Ag&Au]

Originally Posted by 65CV

Ken-

You are definitely correct that "The problem could be occuring sooner because of an obstruction in the pipe labelled "11D".

Don't you think that the problem could also occur because of flooding at the same location? If Ronnie is letting all the water out at once, the assumption of two phase flow could fail, leaving him with a choked vent. Worse yet, a bit of a Venturi effect.

John

Yes, I do think that is what is actually happening. The reason I mentioned the possible obstruction was to try to explain why it wasn't reported more often by other owners, since I now suspect a lot if not all trailers are plumbed like this. However, after thinking about it some more, I realized that if it happened in my trailer, I most likely wouldn't notice it. If my assumption is correct that, unless the tank in nearly full, the only water that will end up in the shower is the water in the shower drain trap, then there is a good chance I would never notice. We don't normally towel down the shower during a trip, so there is usually a little water right near the drain most of the time. If my theory is correct, the water in the shower would run back down the drain as soon as the sink drain flow subsided.

If I remember this next spring when the trailer comes out of storage, I will try dumping a full sink of water and look in the shower while it is going down.

Ken

[bike_addict]

Originally Posted by w7ts

However, after thinking about it some more, I realized that if it happened in my trailer, I most likely wouldn't notice it. If my assumption is correct that, unless the tank in nearly full, the only water that will end up in the shower is the water in the shower drain trap, then there is a good chance I would never notice. We don't normally towel down the shower during a trip, so there is usually a little water right near the drain most of the time. If my theory is correct, the water in the shower would run back down the drain as soon as the sink drain flow subsided.

It is a significant amount of water that backs into the shower. It was nearly half full to the lip when I found it. It took quite awhile to drain, as in I went to bed because I was tired of waiting. And my tank was no more than 25% full (per the sensor) prior to that. After draining the sensor showed about 25% again.

There is no question that there is a flaw in the system due to lack of venting. The people I've talked to at AS admit that and say that this is the fix. This valve is what it takes to prevent the water flow from overwhelming the venting. They won't argue that fact with you, they admit there's a flaw. But this is the solution they are offering.

[bike_addict]

Originally Posted by 65CV

Ken-

You are definitely correct that "The problem could be occuring sooner because of an obstruction in the pipe labelled "11D".

Don't you think that the problem could also occur because of flooding at the same location? If Ronnie is letting all the water out at once, the assumption of two phase flow could fail, leaving him with a choked vent. Worse yet, a bit of a Venturi effect.

John

I will check 11D once I get the trailer back. And I like the idea of using the flex hose to check it.

I can't say that I know what you mean by "two phase flow" or "venturi effect". I'm still pretty green but this crash course is helping...

[Ag&Au]

Originally Posted by bike_addict

It is a significant amount of water that backs into the shower. It was nearly half full to the lip when I found it. It took quite awhile to drain, as in I went to bed because I was tired of waiting. And my tank was no more than 25% full (per the sensor) prior to that. After draining the sensor showed about 25% again.

There is no question that there is a flaw in the system due to lack of venting. The people I've talked to at AS admit that and say that this is the fix. This valve is what it takes to prevent the water flow from overwhelming the venting. They won't argue that fact with you, they admit there's a flaw. But this is the solution they are offering.

Looking at your PDF, I see no way any more water than what's in the shower drain trap (or perhaps more of the shower drain plumbing if some of it is sloping the wrong way) could end up in the shower unless the tip of the pipe into the tank from the shower drain (11M) was below the surface of the water in the tank. That brings up another entirely different possible cause. Keep in mind that I am only trying to explore the possibilities. I am not suggesting that you have any option other than to follow their path of trying to fix the problem.

Ken

This has me puzzled If I were a member of the top 1% , I would buy you a new trailer and tear the one you have apart to solve the puzzle.

[Goal15]

So I guess this means that we should all be looking at the possibility of retrofitting with Hepvo valves?

[Ag&Au]

Originally Posted by Goal15

So I guess this means that we should all be looking at the possibility of retrofitting with Hepvo valves?

I think that if this has never happened to you, then you don't need to do anything.

It would be any interesting experiment to have a whole bunch of people with newer trailers fill their sinks and drain them while watching the shower floor.