Grey Water Tank Problem

[jerrybeaird]

Thanks Charliem for the detailed explanation.  I will be trying the gallon jug test again without the AAV in the bathroom sink.  I just settled in at Lake Conroe, TX for the weekend and since I have full hookups it will be easier to do.  It is our second adventure!

I will report back my findings for others to know too.

I hope that you have a speedy recovery on that knee replacement.

Thanks
John

[hdrehder]

I'm "in" Charliem. Thanks for the post. I want to make sure I get this right... 5 gallon buckets of water down the shower drain. I'm looking for a premature fill of the grey tank as well as gurgling in the sink. My warrantee is up in a few months, so I'd definitely like to get this figured out soon. Will take me a few weeks before I can get the test done.

[kycamper]

Did you need me to retest with the AAV removed?

My local Camping World didn't call me back to do warranty work. I thought since Thor owns both, I'd get better service. I will try again soon. then I'll ask Livin Lite for help

[charliem]

[font size="3"]nd1979: [/font][font size="3"]That would be good. If it fails with the AAV in place and passes with the AAV removed it proves the vent is submerged.

CMac: That's correct. When pouring into the shower you should hear and see gurgling and splashing from the sinks before the tank is full. Keep a count of the buckets so you know how much water you're pouring in. The tank should hold around 30 gallons when physically full. You can also run the test by pouring water into the kitchen sink.

gleamb: Yes a retest without the bathroom AAV should allow complete filling with no gurgling or back spray. Keep track of how many gallons you're putting in. [/font]
[font size="3"]On the CW contact, I called Don in LL warranty and told him what was going on. He gave me his phone number which then gave to the CW guy. All seemed to go smoothly.

All: I've diagrammed the whole DWV system trying to understand what's going on. I can find no way for the problem to be "fixed" by replacing the AAV with a working AAV. The AAV should let air pass in only one way: into the tank, not out of the tank. Now I'm looking at what happens if the combined kitchen/bath drain pipe is pushed too far into the tank. Physically that's also possible. But it's getting late and I need another "happy" pill 
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[jeeps]

[font size="3"]We have had this happen once.  Both sinks stopped draining and then a gush of air came back through the sink drain and it all drained.  Will do the test and report back.[/font]

[charliem]

[font size="3"]To further the conversation on the gray tank problem I submit the attached drawings.


[attachment id="915" thumbnail="1"]

Figure 1 is a schematic of the gray water system on a 21RBS, but it should be representative of other models with exception of the bathroom sink. Gray water fills the tank through two entry pipes. One drains the shower and also serves as the wet vent for the tank. The two sinks are combined to drain through the second entry pipe. Each drain has a P-trap to prevent tank gasses from backing up into the trailer. The shower is directly vented by the wet vent. Eeach sink is vented by an Air Admittance Valve (AAV). These AAVs let air into the drain pipe downstream from the P-trap to prevent water from siphoning out of the traps. As shown in the drawing both entry pipes are connected to, but do not penetrate, the gray tank. This is the ideal installation. Air displaced by additional water from either entry pipe is vented out the wet vent to the trailer roof.  Note that the vertical scale is not accurate. The tank itself is only about six inches tall.
[attachment id="918" thumbnail="1"]

Figure 2 depicts an installation error where the vent pipe extends some distance into the tank. The drains will perform properly until the water level reaches the bottom of the vent pipe. At this point the trapped air can no longer exit via the vent, but will be forced back up the sink drain pipe and out one of the sink P-traps. This causes the gurgling sound and water from the traps being splattered out of the sinks. I believe this is the condition we are seeing. Depending on how far the vent pipe protrudes into the tank, symptoms will appear at various levels less than 100% full.

[attachment id="919" thumbnail="1"]

Figure 3 depicts a similar situation, but the pipe from the sinks is pushed too far into the tank. I believe this is physically possible during assembly, but I don't have any idea how probable it is. I'm still trying to think through the symptoms from this configuration. I think air trapped in the sink drain stack would be compressed and forced out one of the sink P-traps as water is added. This may cause gurgling, but it might just make the sinks drain very slowly. Either way the tank will act as if it's full long before it really is. Each time a sink is emptied the AAV will let a new charge of air into the pipe. More thought is required here. In a properly operating system the gray water should begin to back up into the shower first because the shower is the lowest drain.

All this assumes the AAVs are working properly, admitting air in only one direction. If an AAV is stuck open, or not even there, the tank will be vented out the failed AAV. In Fig 2 the tank will appear to be filling correctly, but any tank odors will vent into the trailer. In Fig 3 it's probably similar, but I'm still thinking on this. If an AAV is stuck closed there is probably an effect on the sink P-traps. If sucked dry, odors will back up into the trailer through the dry P-trap.
So what's the worst case? Figure 2 and a failed or absent AAV. The drains would work properly, but odors could be noticeable. If, as some campers do, the sewer hose is left connected to the CG sewer, the gray drain valve is left open, an AAV is stuck open, and a vent fan is running. Phewweee!

All comments, suggestions, additions, or subtractions are welcome. My goal is to build an understanding for us and LL so this problem can be put in the history file.    

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[jerrybeaird]

Well, I just did the test.  I filled it back up until the kitchen sink stopped draining.  It could be that I  was on a slight slope before and not now but the tank read 1/3 full.  I  unscrewed the bathroom AAV and just before it was totally off I could feel and hear the air get sucked in.  When It was off on the next turn, a big whoosh of air was sucked in and the kitchen sink drained.

I screwed it back in and added more water in the kitchen sink until it stopped draining and now I am at 2/3 full.  I screwed off the valve again and again, a big whoosh of air and the water drained again, just as fast as the first time.

I repeated this again, and for the third time it repeated the pattern.

So, I might have a bad AAV or maybe a vent pipe issue like charliem described in fig 1 or fig 2.

[jtelles3993]

Thanks Charlie - the diagrams really help a lot!

Ran my GW test today in 3gl increments via the kitchen sink. I marked a 5gl bucket using 3 fills from a 1gl milk jug. At 9 buckets (27gls) all was still good. I then started pouring 1/2gl at a time with a tea pitcher - the bathroom sink gurgled and everything stopped at 27.5. Since there was no water coming up through the shower pan, I assumed there was still some capacity in the holding tank - should have been about 5gls? I poured a gallon into the shower pan to verify and it did not drain either. Obviously there might be some margin of error in the actual capacity of the advertised 32gl GW tank - my bucket measurements weren't QC perfect but not off that much?

I could live with 27gl capacity and it would probably be fine - but I'm not sure I want to let LL off the hook on this? I suppose I could removed the AAVs and try it again to at least compare the results - but I'm with Charlie, the faulty AAV thing just doesn't make sense? But then again - it seems to have solved his problem? With a dry shower pan and stopped up sinks, a small air lock caused by figure #2 makes the most sense - a bore scope would definitely tell the tale.

PS, I also checked my tank gauges through the process - definitely will be upgrading those some day.

Edit, my CL was level - but no way to tell if the tank was? Another possible culprit?

[charliem]

[font size="3"]nd1979: [/font][font size="3"]Are you sure the whoosh was air being sucked in? Not air being blown out? My thinking says the air should be getting trapped in the tank when the vent pipe is submerged. That would stop the draining. Then, when you opened the AAV the trapped air would be released (blown out) through the AAV pipe and draining would resume. If that air is truly being sucked into the open pipe it would indicate a faulty AAV. The AAV's whole function in life is to admit air into the pipe at that point.

surfsup: The 27 gal number may not be too far off. The usable tank capacity is highly dependent on the tank being level and how completely it was drained previously. The trailer has to be level to well within less than 1 degree side-to-side and front-to-back. Those big flat tank bottoms don't have to be off much to make a big difference in capacity. Levelness also affects how well the tank drains, thereby affecting your capacity runs. I ran three different gallon tests just as you described and got 27, 33, and 33 gallons. The 27 reading was at some earlier time and I didn't go back to resolve the discrepancy, but I do remember the 33 gallon readings had some water standing in the shower. Most of us are seeing problems around 1/3 to 1/2 full, but you may have the vent pipe just barely penetrating the tank. Trying the test with the AAV removed would answer that. And as far as your gauge readings, you'll love your new SeeLevel  

 
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[jerrybeaird]

Yes, it was air being sucked in for sure.

[charliem]

[quote source="/post/7791/thread" timestamp="1426373032" author="@nd1979"]Yes, it was air being sucked in for sure.[/quote][font size="3"]OK. In that case you get off easy. Just replace the faulty AAV. I need to recheck mine when I can walk again. It may be that I've been wrong all along and I just had a bad AAV from the beginning. But that still doesn't explain the splattering and regurgitation I had from the sink drains and I don't understand how that much vacuum could be generated by putting water into the tank. Believe me, I'd love for a bad AAV to have been the problem. Thanks for your work.
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[kycamper]

JUST replace the AAV with WHAT?? Where do we purchase them? Same brand or do we try a different manufacturer ? My trailer is new and under warranty....why would I have to do this and not Livin Lite???

I sure wish someone at Livin Lite would monitor these forums. hey need to know what is going on. When I spoke with Don about this problem, I asked him if he had ever heard of it from other owners. He said he HADN'T !!!!?!! Really?

[shovelhead]

I'm testing tomorrow since I planned to de-winterize.  I'm 1 week out of warranty. Crossing my fingers.

[jerrybeaird]

I sent an email to Don this evening describing my test fills and removing the valve, and asking him to send me a replacement.  I would hope that he will send them to us as it will be cheaper than going in to CW for a warranty claim.

[shovelhead]

[video src="https://youtu.be/nCMu4WfiIvg"][/video]


I'm not a plumber but this helped me understand what the AAV does.