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Topic: Shower Not Draining - Vent Location?? (Read 555 times) previous topic - next topic

Shower Not Draining - Vent Location??

My shower is not draining and I suspect there is a venting problem. No other water drains are having a problem.  I've confirmed that the tank is empty and there is no blockage.  If I open the grey tank it creates a vent and then the shower will drain. 

I see two of those black vent caps behind the washer/dryer is one of those for the shower or should I be looking somewhere else?  I don't see that the pipes behind the washer/dryer are attached to go to the shower area.

Any help would be appreciated.
2009 Nimbus CE
2016 Jeep Cherokee Trailhawk
 ̷2̷0̷0̷6̷ ̷C̷o̷u̷n̷t̷r̷y̷ ̷C̷o̷a̷c̷h̷ ̷I̷n̷s̷p̷i̷r̷e̷

Re: Shower Not Draining - Vent Location??

Reply #1 –
Check on the roof.  At least on earlier coaches the tank vents are on the roof, not inside the coach.

It is possible that the PVC pipe to the roof has fallen down into the tank/below level of fluid in the tank so it will not act as a vent.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Shower Not Draining - Vent Location??

Reply #2 –
On our 2003 U320, there are 5 air admitance valves (the ones you pictured).

The two behind the washer are both for the washer on our rig.  One by kitchen sink, one by bath sink, one by shower (on our rig, in the hamper behind the toilet).

Try and figure out where the drain line runs from your shower, and there will be a AAV on that line.

In addition, on our rig, there is one roof vent that is for both the black tank and grey tank.  One roof vent serves both.

That is how our 2003 is set up, yours may vary.

Dan - Full timing since 2009
2003 U320 40' Tag 2 slide

Re: Shower Not Draining - Vent Location??

Reply #3 –
Well that's sort of good news that I don't have to remove stackable washer / dryer.  However, my shower is on the driver side adjacent to the washer dryer and the toilet is on the passenger side.  Now I have to see how I get behind the toilet to look.


Quote from: AC7880 –
On our 2003 U320, there are 5 air admitance valves (the ones you pictured).

The two behind the washer are both for the washer on our rig.  One by kitchen sink, one by bath sink, one by shower (on our rig, in the hamper behind the toilet).

Try and figure out where the drain line runs from your shower, and there will be a AAV on that line.

In addition, on our rig, there is one roof vent that is for both the black tank and grey tank.  One roof vent serves both.

That is how our 2003 is set up, yours may vary.


2009 Nimbus CE
2016 Jeep Cherokee Trailhawk
 ̷2̷0̷0̷6̷ ̷C̷o̷u̷n̷t̷r̷y̷ ̷C̷o̷a̷c̷h̷ ̷I̷n̷s̷p̷i̷r̷e̷

Re: Shower Not Draining - Vent Location??

Reply #4 –
Quote from: jimgior13 –
Well that's sort of good news that I don't have to remove stackable washer / dryer.  However, my shower is on the driver side adjacent to the washer dryer and the toilet is on the passenger side.  Now I have to see how I get behind the toilet to look.



Your coach could be different.  Here is a thread about mine.
Sewer Odor, roof sewer vent, air admitance valves inside... 
Dan - Full timing since 2009
2003 U320 40' Tag 2 slide

Re: Shower Not Draining - Vent Location??

Reply #5 –
Quote from: jimgior13 –
I see two of those black vent caps behind the washer/dryer is one of those for the shower or should I be looking somewhere else?  I don't see that the pipes behind the washer/dryer are attached to go to the shower area.
Any help would be appreciated.

Those black capped vets are vacuum breaks to keep the flowing water from sucking the trap dry.  There is a roof vent to allow air to flow in and out of the tank as necessary.  As others have said look there.  "I" would run a hose into that roof vent and make sure it's clear.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Shower Not Draining - Vent Location??

Reply #6 –
Quote from: Old Toolmaker –
"I" would run a hose into that roof vent and make sure it's clear.

Yes, using a hose or bucket to pour water down the vent will  prove that it is not blocked. But, the pipe could still have fallen below the liquid level and NOT able to serve as a vent.

I would blow air down the vent to verify that the pipe has not fallen below liquid level in the tank. If someone by the wet bay hears air hissing down there, all is well.  If they hear it blowing bubbles in the liquid-- not so much.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Shower Not Draining - Vent Location??

Reply #7 –
Quote from: Old Toolmaker –
Those black capped vets are vacuum breaks to keep the flowing water from sucking the trap dry.  There is a roof vent to allow air to flow in and out of the tank as necessary.  As others have said look there.  "I" would run a hose into that roof vent and make sure it's clear.
If the roof vent was the issue wouldn't all my drains not empty?
2009 Nimbus CE
2016 Jeep Cherokee Trailhawk
 ̷2̷0̷0̷6̷ ̷C̷o̷u̷n̷t̷r̷y̷ ̷C̷o̷a̷c̷h̷ ̷I̷n̷s̷p̷i̷r̷e̷

Re: Shower Not Draining - Vent Location??

Reply #8 –
Quote from: jimgior13 –
If the roof vent was the issue wouldn't all my drains not empty?

The sink drains would vent through the tub drain.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.