Question for thech heads about sewer gas

[Billy Dean]

My wife & I have had many RVs and they all stunk at times from the black water tank. We thought the Jay Flight was going to be different. It didn't smell for a while, but then it came.

Today, I installed a sewer vent cap made by Coil n ' Wrap named Xtreme Vent. The vent spins around to face the wind. It creates a negative pressure in the sewer system, drawing out the gasses; whether it be black or gray water.

It seems to work like advertised. My question is how does the gas get into the RV? The only thing I can figure is it comes out the sewer vent & gets blown in the Fantastic roof vent down into the trailer. I have thought of how the gas could maybe come from around the toilet, but that has a water seal at the flush valve. Maybe it's not sealed at the floor?

Does anyone know?

[barrelslime]

I dont know if this is a definate answer but how does the GAS get in to the RV. Well as mentioned its a gas and must be sealed very well to contain the smell. Also its a gas and builds some pressure which means the sealed tank must be sealed well or the pressure is gonna find a way out. Thus the need for a vent to keep pressure from building. Fact is septic tanks are buried outside your home to keep the smell out of your home. Imagine if you had a holding tank in your basement, that needed empting periodiclly. Your house would smell.

[ByDesign]

There are several possibilities. Outside sewer hose/line. Blockage in vent.
The Fantastic fan could a possibility if it's blowing "in" to your RV. Some Blank Tank additives can mask it, but it still may be there.
In my situation, my PVC hard-line is becoming separated from the sewer access opening, another project on the list.

I imagine the scent may be hard to track to the exact point of entry.

[Seann45]

It can also come through the toilet seals..

[Billy Dean]

SEVERAL YEARS AGO, I TOOK THE TOILET OUT OF ONE OF MY RVs. I kind of remember that there is a large pipe going down from the toilet that slips inside the pipe coming up from the blk wtr. tank. It wasn't a tight fit, so there is not an air tight seal. So I've concluded that's where the gas & stink is coming from. I believe the gas then seeps past where the toilet rests on the floor. It couldn't come past the flush valve because it's sealed with a layer of water. I believe when the wind blows against the blk wtr vent, the gas is forced down the vent pipe and into the trailer. This can happen when the trailer is parked with a strong wind or as you go down the road which creates a strong wind. Since installing the sewer vent caps mentioned earlier, we haven't ever noticed any sewer smell. It seems to really have solved the problem. Try it; you'll like it.

[rvrev2]

I noticed that if I have the bathroom vent running, and I flush, that black tank odors are literally sucked into the coach. I keep having to remind myself to close the roof vent before I flush.

[jayco32rls]

Originally Posted by rvrev2

I noticed that if I have the bathroom vent running, and I flush, that black tank odors are literally sucked into the coach. I keep having to remind myself to close the roof vent before I flush.

This effect is caused by a low pressure situation. Because the vent fan is on this causes the static air pressure in the TT to be lower than that in the black water holding tank. Air will always try to flow from high pressure to low pressure thus causing the "stink" to come into the TT from the flush valve when it is opened. Thats also why the spinning tops that go on the black water tank vent work. When the air flows by the opening it creates that same low pressure situation, causing the tank fumes "the stink" to want to go out the top of the vent ( high pressure to low pressure). Hope this helps a little.

[Seann45]

Camping world and a few other places now have a solar powered sewer vent fan.. gonna get me one next time I am at a CW

[ByDesign]

Hhhhhmmmm, i can smell a mod brew'n !!!!