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
SJ-Chris wrote: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.
The liquid would NOT rise UP the vent pipe beyond the liquid level (1 inch? 2 inches? 3 inches?). As more liquid is put into the tank (from the toilet), it would simply flow into the black tank. I agree with the OP that as liquid is flowing into the black waste tank, some air will release back into the toilet.
-Chris
IN NORMAL operation the liquid in the tank will not raise above the bottom of the toilet ball valve. BUT, if you connect the Black Water rinse and FORGET it, the water pressure WILL push the water UP the vent pipe and on the roof and IF the 1.5 inch vent pipe is NOT sealed correctly at the roof that black water will flow into the roof cavity. BIG MESS and smell. There can be 2 possible problems. The 3 inch toilet down pipe protrudes into the tank too far. OR the 1.5 inch Vent pipe also protrudes into the tank too far. I have seen BOTH happen but not both at once. DUMP THE TANK. Then flush the toilet a few times. IF not burping or same type problem, then the vent or 3 inch is too far down. Doug
