Unknown odor source.

[geokeg]

An odor that smells like a sewer sometimes occurs during towing and is  quite strong when opening up the trailer after towing for a few hours.  There seems to be no correlation to grey or black tank contents or level of fullness.  Prior to closing up and towing there is no odor.  I am thinking air pressure coming back through the vent system somehow.  Has anyone else experienced this or have an idea on the cause or fix?  After a short period of time venting the cabin there is no detectable odor.

[STEVEnBETTY]

Geo keg, my theory on sewage smell in the trailer involves the p trap in the plumbing. You have the same basic system in your home, i’ve found that if I leave open the shower backup valve or the bathroom sink and kitchen sink stoppers when I dump my waste tanks the water in the p traps sometimes gets sucked out. So now when I dump, or travel down the road, all the valves and drains are closed.

 

Steve

[topgun2]

On the rare occasion that I've had this issue I've used a grey tank deodorant that has taken care of the issue.

 

https://www.amazon.com/Grey-Water-Odor-Control-Treatment/dp/B0006H92QU/ref=sr_1_1?keywords=grey+tank+deodorant&qid=1559393244&s=gateway&sr=8-1

 

Bill

[John E Davies]

You are smelling gas from the grey water tank. There are four ways for that tank to vent ... through the sink or shower traps, or through the 2” pipe roof vent. (The black tank is always vented through the roof, and through the toilet bowl.) The galley traps and roof vent are closed off when towing because of the grey tank isolation valve. That leaves just the galley sink.

 

If you travel on steep mountains passes or maybe when the weather gets really hot, the tank pressure increases and it may burp stinky gases past the water in the trap and into the galley.

 

The tank needs to have a second OUTSIDE vent in back to prevent this while towing. It is a design flaw and I just don’t understand why they build them this way. All you can do is treat the grey water so it smells like lemon instead of swamp gas.

 

As a test, close your isolation valve, fill the galley sink full and then remove the drain. The water flows out fast then slows way down. Open the isolation valve and the water disappears fast because the trapped air in the tank can now escape out the roof vent.

 

Complain to Oliver. If enough people do, maybe they will correct the defective vent system. I started a thread a couple of years ago suggesting a second vent and most people responding did not feel it is a problem and felt that we should just live with it. But would you tolerate this in your home?

 

John Davies

 

Spokane WA

[geokeg]

Thanks guys, I love this forum!  I will get a grey tank deoderizer and give it a try.  The situation has been intermittent but I think John has it nailed with his theory.  We had 2 trips over Steven’s Pass on I-90, on hot days. About 3,300 feet of elevation change plus density altitude effects.  When my ears were popping the grey tank was burping.

 

My grey tank was about 50% full so the p traps had to have water in them.  But, I will try Steve’s idea for dumping with valves closed to maybe avoid sucking the p traps dry.  I probably should plug both sinks when I drain the grey tank for insurance of that.

 

Thanks again for your inputs!

 

George

[John E Davies]

 I will try Steve’s idea for dumping with valves closed to maybe avoid sucking the p traps dry. I probably should plug both sinks when I drain the grey tank for insurance of that.

If everything is closed up tight and the tank is full, it will not dump very well. There has to be a big opening for outside air to enter to prevent a vacuum from forming. Some air will go back up through your stinky hose if it isn’t blocked by a drooping section full of water, but that isn’t reliable.... Just always pull the isolation valve forward (opens the vent) and don’t worry about plugging the sinks. The air will come down from the roof. You can always run the faucets for a second afterwards, if you want to make sure there is some water in the traps, and that is the time you can add a few ounces of tank deodorizer. Don’t forget the shower trap, if you don’t use the shower that one may dry out through simple evaporation.

 

John Davies

 

Spokane WA

[geokeg]

All excellent points John, thanks!  Especially the shower drain drying out, we never use it ?‍♂️.  That one really makes sense and is most likely my source of the aroma.

 

 

[bugeyedriver]

On my Elite, I've always found the source to be the galley sink.  If the road is rollicking of bumpy enough, I think the p-trap at the sink sloshes the water out and the fumes are able to enter the Ollie.  I've always been able to remedy this by pouring water into the sink to refill the trap.