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Let me say at the outset, I appreciate those of you who opined and gave me good advice on what should be a very straight forward plumbing problem. Well, maybe not so straight forward. I have three vents in my 40' Class A motorhome.

 

  1. Two roof top vents. One for a half bath and the other for the main bathroom which includes a shower and washer/dryer. Upon inspection both of these roof-top vents had sealant or glue covering the hole.
  2. A vent for the double-bowl sink in the kitchen which is part of the slide, so the vent is inside the cabinet.

So after cleaning the "gunk" (that is a plumbing term...I wish) out of the two roof top vents the gurgling did not go away. The vent inside the kitchen cabinet is new and is working fine. I know that because before replacing it the kitchen sink(s) did not drain and thus the minute I replaced it...woosh, the water evacuated the sinks.

So the "annoying mystery" continues. 

Rest assured I have consulted an RV dealer-friend, but at the moment I have no desire (or intention) to call an RV-repair person to come trouble shoot this for two reasons, maybe three: (1) I am too cheap, (2) it is only annoying and (3) I am hoping that this "network" or RV sympathizers can help me.

Happy New Year and thanks.

 

ventcover.JPG

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30 minutes ago, Kirk W said:

Might it be that the previous owner of your RV did that in an effort to make that noise go away? That would seem to indicate that the problem is not a new one. 

I suppose anything is possible, but common sense and knowing the basic physics would argue against that. I have contacted Thor to inquire of them what they think. 

 

Thanks. 

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I am not optimistic as I presume that they will say take it to one of our nearest dealers and have an authorized dealership look into it. Of course they will not pay for it (a) and how does a full-timer just pick up and drop off the coach while someone is digging around one's house (b).

But I certainly will let you know. Gurgle, gurgle. Glad I have Tums.

 

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Tim,

This sure seems like a venting issue still, but my only thoughts in reading through this and the previous post is possibly to determine if the gurgling is being caused by air being pushed into the trap or pulled out of it. I'm going to guess that it's air being pulled in because if it was the other way around it would probably be accompanied by some noxious smells.  If you aren't sure, perhaps taping a square of saran wrap over the drain might tell you for sure.

I'm not sure if knowing this will necessarily help diagnosing the issue, but it might. The only other thing I could suggest would be to check for any other air admittance valves that might not be letting air in as they should.

A work-around option would be to install a HepvO valve in place of the wet p-trap. It won't solve the actual problem but it should make the symptom go away as there will be no water to gurgle any longer.

https://www.amazon.com/HEPVO-BV1BUB112-1-1-2-Trap/dp/B00NLMPLDU

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I had had a similar gurgling problem with my kitchen sink a few months ago.  In addition to replacing the air admittance valve which appeared to be clogged, I also discovered a small leak at a fitting in the waste line.  My theory is that this leak could allow air to enter as well as water to leak out.  All I know is that the combination of fixing both of these seems to have resolved my problem.

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Thanks. we have replaced the valve and have no visible leak or water. The curiosity is that the gurgling happens when the shower in the mater bath and the washing machine is discharging, so it does not happen when water is running out of the sinks in the kitchen. 

Are you saying that "air leak" is in the vicinity of the sink plumping? Suffice to say that the water coming from the bath, dishwasher and washing machine all use the same line.

Interesting theory, how does one run that to ground? If there air admittance valve were not functioning it would impact the water leaving the sinks...would it not?

 

Thanks.

 

 

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6 minutes ago, Tim and Peggy said:

Are you saying that "air leak" is in the vicinity of the sink plumping? Suffice to say that the water coming from the bath, dishwasher and washing machine all use the same line.

My kitchen sink is in a slide and there's a rather long flexible sewer line leading to a fixed standpipe.  The leak was at a fitting where the ABS coming from the sink met the flexible pipe.  Once I started looking, the leak was obvious--there was a small puddle!  Since the leak was in a area of pipe that is empty when you aren't running the sink my theory is that it acted as an "unregulated air admittance valve".  I can't prove this was the case, but the "burping" I was getting in the sink seems to have stopped by fixing the leak and replacing the valve.

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When you were on the roof checking the vents did you try running water down the vent to ensure it wasn't clogged somewhere between the roof and the tank(s)?  Also, the photo of the vent that was caulked appears that the vent pipe was (is) pushed down too far perhaps limiting air flow?????  All of mine protrude some from the roof.

Lenp

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1 hour ago, lenp said:

When you were on the roof checking the vents did you try running water down the vent to ensure it wasn't clogged somewhere between the roof and the tank(s)?  Also, the photo of the vent that was caulked appears that the vent pipe was (is) pushed down too far perhaps limiting air flow?????  All of mine protrude some from the roof.

Lenp

PROBLEM SOLVED...I THINK

I took the vent off the kitchen line to see if was working. I sucked in and blew out and it seemed to work. I put the vent back on the pipe and for some reason, while doing the dishes, I discovered that the sinks (double bowl) backed up. Hmmm. I took that vent off and the water evacuated immediately.

I left the vent off, ran a short cycle of the washer and no gurgle. Hmmm, could that mean that there isn't enough air in the line to push the vent-flap up to allow enough air to get into the pipe, those creating the gurgle.

Not sure if I have that right, but now do I buy a new vent , or leave it off?

IS IT POSSIBLE THAT i SOLVED IT? 

I am afraid to hear what all of you think.

THANKS TO ALL.

 

 

 

 

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8 hours ago, Tim and Peggy said:

Not sure if I have that right, but now do I buy a new vent , or leave it off?

The reason for the device on the end of that vent like is to prevent air from back-flowing from your waste tanks into the RV. Most of us learn that the odor from the gray tanks is even worse than that of the black. That air from the tanks is most likely to happen when you run a vent fan, when you are driving, or if the wind hits the vent caps on the roof just wrong. You may want to consider upgrading the type of plumbing vent used as there are several different types available. While the type typically found in RVs is the cheapest, they also fail the most often. I have found that the Studor Mini-Vent is much more reliable and lasts longer, although it does require somewhat more space. I have heard good reports on the Oatey Sure-Vent as well. 

71TeiFF2x-L._AC_UL640_FMwebp_QL65_.jpg51JG5hK86zL._AC_UL640_FMwebp_QL65_.jpg

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42 minutes ago, Kirk W said:

The reason for the device on the end of that vent like is to prevent air from back-flowing from your waste tanks into the RV. Most of us learn that the odor from the gray tanks is even worse than that of the black. That air from the tanks is most likely to happen when you run a vent fan, when you are driving, or if the wind hits the vent caps on the roof just wrong. You may want to consider upgrading the type of plumbing vent used as there are several different types available. While the type typically found in RVs is the cheapest, they also fail the most often. I have found that the Studor Mini-Vent is much more reliable and lasts longer, although it does require somewhat more space. I have heard good reports on the Oatey Sure-Vent as well. 

 

Actually Kirk, the main reason for the air admittance valve is to keep water that is moving through the drain from causing positive or negative pressure that would cause the water in the P-Trap to be removed and possibly allow gases to flow through the P-Trap into the coach. They are required for any system with standing water P-Traps but not required for mechanical traps like the HepvO valve as it doesn't rely on trapped water for the seal.
 

 

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17 minutes ago, Shawn Patterson said:

Actually Kirk, the main reason for the air admittance valve is to keep water that is moving through the drain from causing positive or negative pressure

Actually Shawn you are wrong. Leaving an open pipe as Tim has suggested would accomplish that quite well, if you do not mind the odors when air moves into the RV from the waste system. 

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1 hour ago, Kirk W said:

Actually Shawn you are wrong. Leaving an open pipe as Tim has suggested would accomplish that quite well, if you do not mind the odors when air moves into the RV from the waste system. 

The need for the valve in the first place is as Shawn stated.  As Kirk said it also needs to seal to keep odors and gases from your RV.  A faulty valve can certainly cause the problems you describe.  I would replace it.

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