Black Tank Vent

[Danjo]

How big of a black tank vent do I need? I’m about order a tank and need to finalize this. Thanks for your help

[Johnny Mullet]

Depends on how much poop you wanna haul around. If my skoolie was gonna haul poop in a tank, then I would want at least a 2" pipe venting to the roof above any vents or hatches.

[Danjo]

Originally Posted by Johnny Mullet

Depends on how much poop you wanna haul around. If my skoolie was gonna haul poop in a tank, then I would want at least a 2" pipe venting to the roof above any vents or hatches.

Haha, yep haulin poop. I was hoping to run smaller, but it looks like 1 1/2” is the minimum allowable size. According to who I don’t know, RVIA, UPC?

I was hoping to go smaller to minimize wall thickness.

[Frochevy]

Hey I'm having the same question as I'll be mounting tanks soon... Any thoughts on connecting the gray and black tank vents together and only taking one up?

Any issues with a long horizontal run, T into gray tank then going out and up the back of bus? (Trying to eliminate more holes in roof of bus...

[JDOnTheGo]

I agree with Johnny - 2" is the way to go (when possible - the ideal is sometimes not practical). I theorize that those who complain about tank smells do not have a properly vented system.

I can't think of a reason that T'ing the two tank vents together would be a problem. However; a long horizontal run of pipe is bad, slight angle up is better, vertical is best. I suspect it is impossible to have ONLY a vertical run but I'd keep the less than vertical runs as short as possible.

[Danjo]

Originally Posted by Frochevy

Hey I'm having the same question as I'll be mounting tanks soon... Any thoughts on connecting the gray and black tank vents together and only taking one up?

Any issues with a long horizontal run, T into gray tank then going out and up the back of bus? (Trying to eliminate more holes in roof of bus...

No problem joining as long as there is a P-trap to keep gases out. The long run might be a concern if for instance it rains and is sitting at an angle that causes water to collect and stop venting. It could also fill with waste water if you wait too long to empty.

There’s also concern about keeping the p-trap wet. If left to sit it will dry out and the gases will be able to come in through the drains