Looking for Info on Fittings for Black Tank-to-Vent Pipe Connection (2020 320 CS-S)

DeanSS007

Less than three days before our final outing of the season and we just discovered that the vent pipe on our 2020 T@B 320 CS-S has become completely separated from the top of the black tank.  I’m working on an interim fix so we can make use of the toilet (sparingly) during our four-day trip to Northern Michigan, but we’ll absolutely need a permanent repair before the 2023 camping season rolls around.

What I'd like to know is how the factory attaches the vent pipe to the black tank on the 320 models, as well as the type, name and manufacturer of the fitting(s) used to attach the pipe to the tank.  The working space behind the bathroom wall is extremely tight on these campers, so it's not going to be an easy job, but first things first.  I wonder if anyone from the NuCamp factory can provide some info and/or photos of how the vent pipe is attached during the manufacturing process; OR, what the recommended fix would be for this kind of situation.

Below are two photos I was able to take -- one showing the pipe resting on the opening to the black tank; and the second shot showing an approximate 1/2-inch gap when lifting the vent pipe up by hand.  Not sure if NuCamp uses a grommet-style fitting for the vertical connection or some other kind of attachment.  I will be removing a portion of the original ABS pipe, which should allow me to better assess the actual hole size at the top of the tank and get a better look at the piping interface (in the light of day rather than in that tight little space using a mirror and my iPhone camera…).

Hopefully someone out there might have some added insight on this situation.  

Thanks,
—Dean & Linda

Sharon_is_SAM

Please contact nuCamp:  Help@nucamprv.com

DeanSS007

I will do that.  Thanks!

DeanSS007

Eureka!!!  All fixed and ready for our fall color tour this coming week. Here's what happened (for anyone who's interested):

After cutting through the horizontal portion of the vent pipe toward the driver's side of the bathroom access panel, I pulled out the L-shaped leg and got a much clearer view of (and physical access to) the pipe-to-tank opening.  

Once I looked at the broken end of the pipe, and having read an older post about repairing a broken grey water connection in a T@B 400 ( https://tab-rv.vanillacommunity.com/discussion/14507/solved-and-fixed-please-help-plumbing-broke-on-shower-drain/p1 ), I realized that the ABS vent riser is (was) threaded into the black tank with a 1.5-inch NPT fitting.  

Using a makeshift extractor, I was able to back out the broken-off threaded portion and replace it with a PVC fitting (a 1.5" DWV trap adaptor), the threaded portion is not NPT but mated just fine with the black tank threads (I applied some teflon pipe dope for added sealing and snugged the adaptor against the tank).  The non-threaded end of the trap adaptor has an outside diameter very similar to the OD of the ABS pipe.  Using a rubber union for 1.5" PVC pipe, I was able to join the new trap adaptor fitting to the vent pipe.  A second 1.5" rubber union was used to join the horizontal portion of the vent pipe to the previously cut portion.  (Side note: The use of rubber unions should allow for some flexure of the pipe, which can help to avert a similar fracturing episode of the tank-to-pipe fitting in the future.)

Now, it's important to note that this fix is what my dear old pappy used to call "field expedient," but it should do the trick since this is not a pressurized system (more like a "sloshing" system).  And, though somewhat frustrating and bothersome, the problem was not insurmountable and I believe everything should function as originally intended for years to come -- plus, it certainly will be much, much (MUCH) better than if that detached vent pipe had gone unnoticed for a while longer.

I don't know when the vent riser broke off of the black tank, but since we rarely use the toilet it could have been a while ago (maybe the 25 miles of washboard road when visiting Badlands NP last year).  With that in mind, it would be a good idea for T@B 320 owners to check that the vent pipe is firmly attached to the tank from time to time, just in case the same thing happens to someone else out there.

Related Costs
Materials: $20
Labor: Free, just me
Damage to psyche: Moderate, yet temporary
Having a properly functioning black tank and vent system: Priceless!!!


Happy trails, Everyone :-)