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09-10-2013, 04:24 PM
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#1
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Retired USAF (kinda)
2013 25' FB Flying Cloud
Meridian
, Idaho
Join Date: Jun 2012
Posts: 106
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Gray Tank Problems on New Airstream
Any ideas why every time we drain the big round sink, nasty water comes up in the shower; besides the fact that something's not right? The gray tank is empty; monitor system says so, and I've drained the system. It's a new unit (2013 Flying Cloud 25FB), so it will be repaired under warranty, but we're on the road on right now and I'm wondering if it could be something simple? What would cause this? Thanks.
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09-10-2013, 04:48 PM
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#2
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Rivet Master
1973 21' Globetrotter
Houston
, Texas
Join Date: Sep 2009
Posts: 3,322
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I'll bet your grey tank vent is plugged. As a result, when a few gallons of water go sloshing down into your grey tank, the air in the tank has no place to go, so it finds a path through the plumbing and out your shower pan. The icky water is whatever is left in the trap and perhaps some that has settled in the pipes. One way to test the theory is connect to open your grey dump valve and then empty that sink-full of water. If it doesn't cause anything funky in the shower, then its a vent problem. You might be able to pick up a fish tape at a hardware store and run it down through whatever is causing the blockage.
good luck!
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09-10-2013, 05:46 PM
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#3
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Retired USAF (kinda)
2013 25' FB Flying Cloud
Meridian
, Idaho
Join Date: Jun 2012
Posts: 106
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Thanks!
Quote:
Originally Posted by Belegedhel
I'll bet your grey tank vent is plugged. As a result, when a few gallons of water go sloshing down into your grey tank, the air in the tank has no place to go, so it finds a path through the plumbing and out your shower pan. The icky water is whatever is left in the trap and perhaps some that has settled in the pipes. One way to test the theory is connect to open your grey dump valve and then empty that sink-full of water. If it doesn't cause anything funky in the shower, then its a vent problem. You might be able to pick up a fish tape at a hardware store and run it down through whatever is causing the blockage.
good luck!
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That's exactly what happens. When connected to an RV Park sewer system and the gray tank valve is open, we don't notice the problem. Only when the valve is closed. Thank you.
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09-10-2013, 06:00 PM
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#4
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4 Rivet Member
2018 30' Classic
Ivins
, Utah
Join Date: Aug 2009
Posts: 424
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Hi, this same problem has been observed on 27FB as well, it appears the grey tank vent design is similar.
Basically, water draining from the galley sink fills up the drain pipe, and prevents the black tank from being able to vent. A better design would have the vent piped directly to the tank.
See http://www.airforums.com/forums/f446...ion-86758.html for additional links and details.
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09-11-2013, 07:37 AM
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#5
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Rivet Master
1973 21' Globetrotter
Houston
, Texas
Join Date: Sep 2009
Posts: 3,322
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I checked out the plumbing diagram on the link above--looks like a marginal design, as the pathway for water from the sink is down the same pipe that vents. Looks like the solution is either a plug in the shower pan, or a slow drain of the sink, or a combination of the two. I suppose the vent pipe could be clogged also, which might exaggerate the problem, but the symptoms described here sound exactly like those reported in the other posts.
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09-11-2013, 10:55 AM
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#6
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Retired USAF (kinda)
2013 25' FB Flying Cloud
Meridian
, Idaho
Join Date: Jun 2012
Posts: 106
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Unacceptable
Quote:
Originally Posted by Belegedhel
I checked out the plumbing diagram on the link above--looks like a marginal design, as the pathway for water from the sink is down the same pipe that vents. Looks like the solution is either a plug in the shower pan, or a slow drain of the sink, or a combination of the two. I suppose the vent pipe could be clogged also, which might exaggerate the problem, but the symptoms described here sound exactly like those reported in the other posts.
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If it's truly a design problem; that's ridiculous for a $70K+ trailer. However, after reading through the entire thread posted above, it sounds as the OP problem was a blocked vent. I still have to explore that possibility.
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09-11-2013, 02:06 PM
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#7
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Wise Elder
2010 30' Classic
Vintage Kin Owner
South of the river
, Minnesota
Join Date: Dec 2009
Posts: 4,169
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The drain design is marginal as there is a 1-1/2" section of vertical pipe 13" long that serves as a wet vent for both the lav and galley sinks. Even if the vent is working properly that would be enough to lead to insufficient venting.
Of course if the vent is blocked that will make it worse.
I am not intimately familiar with the construction of the 25FB flying cloud however it appears to me that it might be possible to remove the air admittance valve from the shower drain and run vent pipe from there to a newly added T just above the existing T on the vent stack. That would clear up the problem.
__________________
To learn to see below the surface, you must adjust your altitude
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09-12-2013, 02:43 PM
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#8
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4 Rivet Member
2018 30' Classic
Ivins
, Utah
Join Date: Aug 2009
Posts: 424
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Quote:
Originally Posted by Jammer
I am not intimately familiar with the construction of the 25FB flying cloud however it appears to me that it might be possible to remove the air admittance valve from the shower drain and run vent pipe from there to a newly added T just above the existing T on the vent stack. That would clear up the problem.
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Unfortunately, the shower drain admittance valve is on streetside, and the vent pipe is on curb side :-(
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09-12-2013, 02:52 PM
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#9
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Wise Elder
2010 30' Classic
Vintage Kin Owner
South of the river
, Minnesota
Join Date: Dec 2009
Posts: 4,169
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Hmm, would make for an aesthetically unacceptable mod then.
__________________
To learn to see below the surface, you must adjust your altitude
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