Gray Tank Odor

[HortMi]

I'm reaching out to the group to see if anyone has had an issue like this.
I have a new 32SA Open Road. About a week ago I started getting a sewer gas smell in the coach. It would come and go. I keep the tanks clean and use chemicals in both the gray and the black. The odor appears to be coming from the gray tank. Here is what happens,if I run the front AC a small amount of air blows through the rear vents in the bedroom. If I run water in the shower the smell comes through the AC vent in the front of the bedroom closest to the hall. If the AC is not running there is no odor.
I contacted RED BAY and they are stumped as well. They tell me the AC vents are sealed. I have checked the air check valves under each sink and they appear to working. As long as I don't run any water there is no order.
I would appreciate anyones imput as to what I should look for. I'm open to all suggestions.I'm trying to avoid a trip to Red Bay.
Thanks in advance.

[luvlabs]

Your A/C system takes in no outside air so your smell is coming from inside you coach - usually the AAV valves or sink traps. So...

Replace the AAV valves and make sure you have water in the sink traps. Do not run down the road with any vents open as that will lower the pressure inside the coach and suck in any unwanted smells. If needed, you can clean the gray tank with the same cleaners used in the black tank. Personally, I would try Dawn and hot water first as that will cut through the grease that is most likely the source of the odors.

[julie pratt]

We had the same issue in our 32SA, we use TankTech RX (amazon). It is a biodegradable product that works like a probiotic. We use this in black and gray tanks. It is an amazing product, it really liquifies waste. Sometimes if the shower odor is strong, we will dissolve one of those scented tablets.

[HortMi]

Well I replaced both AAV valves and the odor is not as bad but it still comes through the one AC vent if the AC is running. When the AC is off there is no odor. The odor is only appears when the shower and AC are running. Im going to try a different chemical in the gray water tank as someone suggested. At least I can still use the coach and will turn the AC off when I take a shower. Tiffin thinks the vent pipe from the tank to roof may have seperated in a joint.I am having a plumber this week snake it with a camera to see if it has or if it is stopped up.
So I see a trip to Red Bay in my future.
Thank You for your replies!

[wildtoad]

In addition to the AAV, and what your plumber may find, if you have a black tank flush system, you may have a bad back flow valve. Don’t k ie about your mh but mine was in the bathroom in the sink cabinet. It is intended to keep stuff from back flowing from the black tank to the flush line. Sometimes these don’t close all the way and allow fumes into the mh.

[irishguy]

Regardless of those issues if your holding tanks are "healthy" you shouldn't have odor issues.

Use "Happy Campers" holding tank treatment as directed. If it is your gray tank then mix one or two scoops of Happy Campers in a gallon of water and pour into the gray tank. Then fill up the gray tank to full and let it sit for a couple days.

[Pigman1]

Originally Posted by wildtoad

In addition to the AAV, and what your plumber may find, if you have a black tank flush system, you may have a bad back flow valve. Don’t k ie about your mh but mine was in the bathroom in the sink cabinet. It is intended to keep stuff from back flowing from the black tank to the flush line. Sometimes these don’t close all the way and allow fumes into the mh.

I think Tom has the answer. We've had a similar intermittent problem and I finally replaced the backflow preventor in my flush system, and NO MORE SMELL. It only took a few minutes to do it, and cost was around $10.00 on line. I was being lazy and living with a minor problem until DW gave me a "gentle" reminder.

[00 Buckshot]

Is it possible your AC is pulling in the odor from one of your roof vents? How close are they?

[luvlabs]

I think Tom's suggestion is a good one as well. The black tank flush vacuum breaker could be a problem.

Doug, there is no connection with outside air and the HVAC system so the A/C unit pulling in odors from outside is not what is happening.

[BobGed]

If you're sure it's a gray tank odor you may want to think about installing a flush sprayer in your gray tank. I just recently did this to my coach...what a difference.

[Ljwt330]

Originally Posted by wildtoad

In addition to the AAV, and what your plumber may find, if you have a black tank flush system, you may have a bad back flow valve. Don’t k ie about your mh but mine was in the bathroom in the sink cabinet. It is intended to keep stuff from back flowing from the black tank to the flush line. Sometimes these don’t close all the way and allow fumes into the mh.

Originally Posted by luvlabs

I think Tom's suggestion is a good one as well. The black tank flush vacuum breaker could be a problem.

Doug, there is no connection with outside air and the HVAC system so the A/C unit pulling in odors from outside is not what is happening.

Assuming the OP's post is accurate as to the source of the odor, the black tank flush doesn't seem to be the issue. The odor only happens when the shower is used and the shower does not empty into the black tank. I agree that the black tank anti-siphon valve could be the source, but it does not gibe with the facts as posted by the OP.


To the OP, does your coach have a washer/dryer, either installed or plumbed for? I knew of the drain pipe/p-trap in my coach but didn't realize there was also an AAV for the washer/dryer as well. I had the same situation as you describe until I found the location of the washer AAV and sealed it (no washer/dryer installed.) Problem solved.


If no hidden AAV, I would think a disconnected vent pipe, as suggested by Tiffin, may be the issue.

[bdpreece]

Everyone is giving you good advice on tank odor problems and since I can't really think of any other solution to tank odors I will throw out one other thing you might want to check.



Next time you smell the odor check your house batteries to see if one of them feels hot. I was getting what I thought was sewer odor and it was actually coming from one of my batteries that had a shorted cell.

[HortMi]

I think I found my problem! I believe the Hepvo valve under the shower is the issue. It works like a p-trap on the sinks but is a straight line valve. Lets water pass through it and then closes. I can smell the odor in the drain. The water from the shower amplifies it and there is a cold air return right above the shower sucking the odor into the AC system. I had asked Tiffin if there was a separate valve for the shower and service said only the two under the sinks.I have replaced both.Two different posters on the FB Tiffin pages asked me to check it. I would have not known the valve was there if not for them. I'm call tomorrow to have him send me a Hepvo valve or I will order it on Amazon. Tiffin said the vent to the roof might have been seperated at a joint. I can only imagine taking the coach into any service center and have them start tearing apart the interior to get to the vent pipe while not knowing about this valve under the shower.
I will post an update and Thanks for everyones replies!

[Peter M]

Originally Posted by HortMi

I think I found my problem! I believe the Hepvo valve under the shower is the issue. It works like a p-trap on the sinks but is a straight line valve. Lets water pass through it and then closes. I can smell the odor in the drain. The water from the shower amplifies it and there is a cold air return right above the shower sucking the odor into the AC system. I had asked Tiffin if there was a separate valve for the shower and service said only the two under the sinks.I have replaced both.Two different posters on the FB Tiffin pages asked me to check it. I would have not known the valve was there if not for them. I'm call tomorrow to have him send me a Hepvo valve or I will order it on Amazon. Tiffin said the vent to the roof might have been seperated at a joint. I can only imagine taking the coach into any service center and have them start tearing apart the interior to get to the vent pipe while not knowing about this valve under the shower.
I will post an update and Thanks for everyones replies!

I had to change mine, PITB. To be sure this is the problem you can block the fumes. Wet two paper towels and lay over shower drain if smell disappears you found the problem. Also, take a wif of the shower drain if the valve is not sealing you will know.