Gray Tank Vent Slipped Down. Apparently

[Jkwilson]

Looks like an off-season fix is in store.

Galley tank has always seemed quick to fill, but this year it has become a real issue. Maybe 10 gallons if we are lucky before the sink quits draining.

Looking for some thoughts about how to verify that a vent slip is my problem, what the plumbing layout is like, if dropping the tank is the only repair option, and how to keep it from happening again if I do have to tear into it to fix it.

How and where do the vents join, and if my vent pipe has slid down into the tank, what has happened on the upper end where it connects to the other pipes?

Appreciate any thought.

[TucsonJim]

Year and model? I'll pull the prints to see if I can get some info.

Jim

[Jkwilson]

Year and model? I'll pull the prints to see if I can get some info.

Jim

Sorry Jim, I realized after I’d posted that my signature wasn’t set up.

2014 303RLS

[TucsonJim]

Sorry Jim, I realized after I’d posted that my signature wasn’t set up.

2014 303RLS

Ah-ha. There was a rash of vent pipes dropping in the 2014-2015 timeframe. They used a different type of gasket back then that allowed for it.
I seem to be missing my 303 floor plans, but I'm going to tag Rob who has a 2015 and is our resident guru on that model. He may know right away how to inspect for the problem and repair if needed.

Cate&Rob

Jim

[Cate&Rob]

Jkwilson
Hi John,

As we both know, we have almost exactly the same vintage 303s . . . and (apparently) this same problem with our galley grey capacity. It is interesting that you have observed a recent reduction in capacity. We thought the same thing was happening, but I dismissed this as not likely/possible . . . maybe it is?

I have always put solving this for the galley grey on the "too hard to do" list because I think the tank has to be dropped to accomplish this. I don't know if the there are separate vent and drain pipes into this tank or if they use the same pipe. Maybe there is a way to come at this through the island where the drain pipe goes directly down into the tank?

I did resolve the capacity problem on the shower grey by retracting the vent/drain pipe that was inserted too for. This one is easy to get to.

Time for me (us ) to get back into resolving this issue.

Rob

[Country Campers]

On my 29RS , same tank layout , I can access the galley vent from behind the wall in the pass thru. The vent connects to the tank right behind the power center. There is a mess of wires there and other obstacles. You both might take a look there to see if yours is similar.


By the look of the space there should be room for about 2 people or maybe more.

Brian

[Cate&Rob]

Country Campers
Hi Brian,

It looks like your black and shower grey tanks are reversed from the 303. Our black is on the starboard (right/curb) side and grey is on the port (left/street) side. The galley grey is crosswise aft of the gate valves (probably the same as yours). The galley grey vent stack connection comes up (deep) behind the converter. What I don't know is whether this is also the drain connection into the tank that can be seen in the forward starboard corner of the island.

Many years ago, I had a discussion with a Grand Design tech advisor (no longer with GD) about going into the island and pulling the drain pipe up from the tank. He could not tell me if this T'd to the vent stack or that was a separate pipe. Either way, this would be a problem. If a glued T connection this would not allow lifting the drain pipe. If a separate connection to the tank, this would not solve the problem. The drain can go below the liquid level in the tank without a problem. The usable volume restriction occurs when the vent pipe is blocked by rising liquid and air cannot get out of the upper portion of the tank, to allow more liquid in.

And this is why . . . despite all the plumbing modifications that I have done to this rig . . . we live with limited galley grey capacity.

Rob

[Country Campers]

Rob

I would think that the galley tank would vent close enough to the hutch so the pipe could be hidden up thru a wall to the roof. I can not imagine that the tank would be held below the floor to allow the vent to be plumbed into the tank closer to the island , but I guess anything would be possible. I think in your picture there is an elbow in between the black and front grey vent pipes , this should be the galley grey , and looks like it will be a chore to get to to see where it goes.

Brian

[TucsonJim]

Rob/John - Just a little more information. On my '14 337 appears to be laid out the same as the 303. My galley gray pipe came up behind the power panel on the hutch, and continued forward into the converter area. I took some photos when the vent pipe broke. Although it doesn't answer the question about whether the two are tied together or not. The DWV plan for the 337 shows that the two are NOT tied together for whatever that's worth.

I'm attaching some of my photos for more data points. I'm wondering if you could remove the electrical panel, slide a borescope probe into the opening and take a look at the top of the galley gray tank? there appears to be a much larger opening for the pipe than what was needed.

Broken galley vent pipe coming up behind the electrical panel in the hutch.


In this view, you can see the broken pipe at the very back of the basement utility space (converter side).

Jim

[Cate&Rob]

TucsonJim
Great pictures Jim. I expect that the build of the 2014 337 is very similar to our 2014/15 303s. I have some more “digging” to do on mine.

Jkwilson

Rob

[Jkwilson]

Thanks for the input so far. I knew this was a challenge, but I’m hoping there is a trick that can save dropping the tank. Borescope will be my first step. Then some thinking.

[webpilot]

On our 2014 337, there is only only one vent on the roof. All three tanks come together to one vent stack. Early on I measured the tank capacity and had the dealer try and fix it. I am 1100 miles from it now, so can't take any photos, but I believe he cut the vent line from the galley tank, shortened it and put in a "Hose" to tie the two pieces of black pipe together. We had much better capacity in both gray tanks after that.

[TucsonJim]

On our 2014 337, there is only only one vent on the roof. All three tanks come together to one vent stack. Early on I measured the tank capacity and had the dealer try and fix it. I am 1100 miles from it now, so can't take any photos, but I believe he cut the vent line from the galley tank, shortened it and put in a "Hose" to tie the two pieces of black pipe together. We had much better capacity in both gray tanks after that.

I used a repair coupling to repair my broken pipe. It held just fine until I lost the RV in the fire.

[Jkwilson]

An update, and a few more questions, as I’ve spent some time working on the rig the last few rainy days. I apologize for the length, but as any of you all that have done this kind of job know, it takes a lot of planning before you jump into it.

First, I don’t believe the vent actually moved. Very little play that would allow it to move without something significant happening elsewhere. My perception that the tank capacity reduced over time was probably just becoming familiar with the trailer.

As others mentioned, the three vents come together at the wall between the hutch and the bathroom. The galley tank vent angles up and forward through the space behind breaker panel. It appears I might be able to cut the vent and pull it up and shorten it, then re-plumb the vent with a flex coupling.

Question 1: (bear with me through the setup) The vent being behind the breaker panel gives me a source of access, but with wiring in the way I suspect not good enough. This space is clearly visible from the basement, but is a long way away with several nearly immovable things in the way. Another option would be through the panel behind the cabinet door that is around the corner from the breaker. How is this panel attached? I can’t see any fasteners. I figure staples from the back side. Exploratory thumping with my fist doesn’t offer much hope for easy removal.

Question2: Is cutting the vent from the top and patching the pipe a reasonable solution IF I can get to it to do it?

The alternative is peeling the coroplast back nearly to the front axle and dropping the tank. Many things like gas line, low point drains and waste line I have to work around to do that. Which leads to...

Question 3: What do you all think about cutting the coroplast? There are screws out in the middle of the trailer between the hutch and the axle which I assume means there is some kind of crossmember running across. Seems I could use that to anchor an H-profile panel joint fabricated from aluminum flat stock or the flat stock and wood to make an access point. I am in the process of dropping the coroplast on one side to be able to see what’s in there. This kind of seems like an upgrade if done right, and would certainly pay off if I need to get back in there for something, like screwing up some part of reconnecting the galley tank plumbing .

Thanks in advance for any thoughts.

[Cate&Rob]

Jkwilson
Hi John,

Some good progress and ideas. I had though (without a lot of research) that the vent pipe was tying into the sink drain pipe such that there was only one pipe into the tank. This was from discussion with a Grand Design rep many years ago and would be the same as how the forward grey tank is plumbed with the same pipe into the tank being both drain and vent.

If these are two different pipes for the galley grey, this makes the task more feasible. We should be able to open up an access to this vent pipe through the inside of the buffet (behind the electrical panel), where an eventual new close out panel would not be visible. Our 303 is closed up and under some snow right now, so I can't take a closer look at the moment.

As far as dropping the coroplast . . . this is one of those projects that seems really daunting . . . until you try it and its not so bad. Somewhere in Howard's story of his plumbing rebuild, he describes how he divided the coroplast into smaller panels more-or-less as you have suggested. https://gdrvowners.com/forum/operati...e-in-a-315rlts

Rob

Edit: John, I just sent you a PM on this . . .