Bathroom sour odor

[Warmrock]

We have an sour odor in one of our bathrooms. The RV is an 2018 Holiday Rambler 35K with a bath and a half and the Vacuflush system. The odor is only in the 1/2 bath.

We have scrubbed the toilet and bathroom, there is no visible floor seal leak, took collar off to inspect.
The toilet is holding water and the Vacuflush system is working and holding pressure.
The vent check under the sink does not appear blocked. (Not sure how to tell if it is faulty)
The black tank has been drained and repeatedly flushed.
The gray tank has been emptied (although registers full).
We have scrubbed the toilet and ball with liquid tide.
Dissolved TST max pods and flushed them to the black tank.

I’m running out of ideas.

Any assistance would be greatly appreciated.

Thanks

Jim

[luvlabs]

Most likely it is your gray tank and a failed AAV (air admittance valve). You can try an deodorize your gray tank with some of your black tank chemicals but you are going to need to locate and replace the AAV valve.

Most AAV valves can be found under the bathroom sink on the sink drain plumbing stack. It's easy to replace and is available at most big box hardware stores.

[Ljwt330]

Originally Posted by luvlabs

Most likely it is your gray tank and a failed AAV (air admittance valve). You can try an deodorize your gray tank with some of your black tank chemicals but you are going to need to locate and replace the AAV valve.

Most AAV valves can be found under the bathroom sink on the sink drain plumbing stack. It's easy to replace and is available at most big box hardware stores.

I agree with the above^^.


You have already found the AAV as mentioned in your post. It is under the sink. You cannot visually tell if it is faulty. It has no moving parts you can see, even the cheap ones which do have a spring and diaphragm, and it is supposed to only let air in, not out from the tank.

Remove that valve and replace it. They are cheap. That is the most likely cause of the odor, especially since this is the only area where it appears.

[Poppedclams]

Replace the aav air admittance valve next to the peatrap. Like post above. Easy and they fail on Amazon they have them like 6 bucks

[Poppedclams]

Oatey 39012 1.5 in. NPT ABS in-Line Vent, Black find this item on Amazon they show location all you need to repair it

[Dutch Star Don]

Often the half bath is over the wet bay and tanks. Make sure your connections are good in the wet bay and that the odor is not wafting up from there into the half bath via the plumbing holes in the floor or cabinets.

[Ljwt330]

Originally Posted by Dutch Star Don

Often the half bath is over the wet bay and tanks. Make sure your connections are good in the wet bay and that the odor is not wafting up from there into the half bath via the plumbing holes in the floor or cabinets.

Don brings up a good point specific to some layouts, and this would also be something to inspect if it applies to yours.

[Old-Biscuit]

Wrap the AAV under bathroom sink with plastic wrap and see if 'odor' goes away
If it does.....replace AAV

[Warmrock]

Thanks All. I replaced the AAV. (All of them). It seems to have done the trick.

Jim

[SteveJ.]

We had a sour small coming from the Dometic 320 toilet. A cleaning with Lysol spray with a toilet brush treatment would e,iniate it but it would come back in a few days. I ultimately filled the toilet plumb full just under overflowing with a bleach/water mixture and let it soak a few hours. This was about two months ago. All good now.

FWIW, the previous owners were not real into the care and feeding of an RV.

[Ljwt330]

I have already posted my suggestion, but I still have a nagging feeling I missed something. First, I am not familiar with the Vacuflush system and second, your description of a "sour smell" is not consistent with my experience of odors escaping from the grey tank plumbing.


SteveJ's post is something you may wish to follow up with, even though your toilet is different (?)

[dfuelman]

Originally Posted by Warmrock

Thanks All. I replaced the AAV. (All of them). It seems to have done the trick.

Jim

I just replaced mine this past weekend also. We found that running the Fantastic Fans without a window cracked open would make the odor problem MUCH worse. This lead me to the vent issue. They were readily available and pretty cheap also. I could tell the rubber flap was stiff and not sealing very well. Would still crack open a window when taking a shower if fans are on, but this is a step in the right direction.

[AKIQPilot]

Originally Posted by dfuelman

I just replaced mine this past weekend also. We found that running the Fantastic Fans without a window cracked open would make the odor problem MUCH worse. This lead me to the vent issue. They were readily available and pretty cheap also. I could tell the rubber flap was stiff and not sealing very well. Would still crack open a window when taking a shower if fans are on, but this is a step in the right direction.

We did that once several years back. Wowza was she sour when we got back inside.

The Oatley AAV's are available at Lowes and Home Depot for under $4 each. On the shelf stocked item.

[Old-Biscuit]

Originally Posted by Warmrock

Thanks All. I replaced the AAV. (All of them). It seems to have done the trick.

Jim

Thanks for posting update and resolution....

Clear air is good!!