Blowback in the WC
Hello fellow RVers.
We have a 2018 Coachmen Pursuit 32 WC.
It has three waste tanks - two for grey water (one for bathroom shower/sink, one for kitchen sink), and one for black.
Every time we flush the toilet, we get "blow-back" from the tank (an air bubble comes from the tank before the toilet drains). Both of the grey tanks appear to have vents to the roof, but the black tank doesn't - unless one of them is teed into the black tank, which I think is unlikely. When I drain the black tank, it sucks in air through the waste pipe before dumping. If we "flush" the toilet during dumping, the tank drains fine.
Am I right in thinking that the black tank might be missing a vent? Is it actually possible that the manufacturer missed this?