black tank not venting?
We have a 2020 high end 5th wheel and also own a 2019 motorhome, and have owned many other coaches. This is the first time we have had this problem and I suspect a black tank venting issue but I welc...
Forum Discussion
Boon Docker wrote:SJ-Chris wrote:
It isn't clear to my why, even if the vent pipe is inserted 1/3 the way down into the black tank, why there would be pressure built up. It isn't a sealed system (because of the vent...even if the tube is submerged) so there shouldn't be pressure. Yes, the toilet might burp a bit, but not actual pressure.
The liquid would rise up the vent tube as the tank fills. When the toilet is flushed the liquid would rush back down the vent tube. Causing a release of pressure through the toilet.
If you've ever done home brewing, they way you carbonate beer is add some extra sugar after fermentation, then seal the bottle, so pressure builds up carbonizing it.
Sewage decomposing will also off gas (different gas types and nasty odors). At 2/3 full, the air space will pressurize pushing water up the vent tube. This may have pushed water up the vent tube far more than you might expect and when you open the toilet valve all that pressure releases.
