2020 T@B400 Black Water Flush and Air8 Work

AirBoss

In case of interest, dealer warranty repairs underway to correct the black water flush valve factory install (vave either installed backwards or hoses reversed so no water getting to black tank) and install the factory Air8 modification kit. Will post more pics later today. Here's bath vanity with sink panel panel removed and the valve. Its mounted behind the wood panel so access is a bit tricky. 

AirBoss

And the swap of lines to get incoming water into the tank, per NuCamp instruction . 

Amazonica

Interesting. thank you for posting @AirBoss.
I too have a 2020 400 and have read about the Black Tank Flush Valve. I *think* mine works but not entirely sure. Makes a water gushing sound when hose is attached and turned on full force, no leaks, but alot of water does come back out of the inlet point once the spigot is turned off and I detach the hose.
 My guess is there may be a time period that is more likely to have this issue? Mind if I ask when yours was made?

AirBoss

Hey there Amazonica. Can't recall date of manufacture but I did find that the Air8 modification (wire mess cover underneath) had already been made (factory or dealer, don't know but likely factory). To your point, flush valve likely a issue on some models up to a certain date. I'd be a bit cautious about full pressure when flushing. as there are some fittings in the system that may not handle high city water pressure. Just a cautionary note. You should see water flowing of the sewer hose elbow when you flush, assuming you are leaving the tank dump valve open, as recommended. You can also just run the flush then go inside and lift seat on head . Should hear water sloshing around in there. Don't get too close, tho!! 🤮

Raydar

Thanks  Airboss. Great pictures and I will have to check my flush connection tomorrow. 

Tabfortwo

Wow there finally utilizing the 1 1/2 in vent pipe for a drain. Instead of drilling directly into the tank.

AirBoss

Raydar said:

Thanks  Airboss. Great pictures and I will have to check my flush connection tomorrow. 

Fingers crossed for ya. It' a fairly easy process if you have to tackle it. About 60 min...plus couple runs to Home Depot! 😉

Raydar

Ok Airboss, looks like I have the same problem. Dewinterize our 2020 T@b 400 bd. Black tank flush doesn't work at all. I looked at the pictures you posted. I'm trying to figure out why there is two hoses, going to the spray nozzle. I saw the black component behind the wood panel. Not sure what that is. My tab was made in July of 2019. 
Looks like I will be fixing this. The dealer is 5 hours away 

AirBoss

@Raydar
It's a fairly straightforward repair (1-1.5 hr), but it is covered under warranty so be sure you're not jeopardizing the warrant by doing it yourself. I was already headed to me dealer for another matter and they're only 35min away so it made sense to have them do it.  

Depressurize the water system. I drained the system using the two low-point valves in the aft compartment, drivers side. Remove small rectangular panel from below the sink. this will expose the hot/cold line and the drain line. Disconnect all three. You then remove the entire sink panel by popping the white caps off each screw and remove them. Be aware there are two screws directly behind the sink itself ( of course there are!) so you'll have to tilt the sink down and use a long-shaft screwdriver to get to them. Panel comes off fairly easily. 

The black component behind the wood panel is a type of check-valve that is supposed to prevent water from backflowing into the system. It allows water in but not out, thus the two hoses. Think electrical...it's not hard wired...it's switched. Apparently during production the hoses got crossed or the valve inserted backwards. Regardless, the issue is the valve closes when you try to use the exterior flush connection instead of opening. 


Snip each hose at mid-point between where they come up through the fiberglass and where they disappear behind the wood panel. Slide hose clamp over bottom section of one cut hose, insert male/male nipple, slide hose clamp up onto the upper section of the OTHER hose, push male/male nipple together and clamp. Do the same for the other hose sections and you're good. Reconnect hot/cold and drain lines, pressurize the system to check for leaks, test run the black water flush and listen for water entering the blank tank by opening the valve on the toilet. You should hear water running into the tank. Be careful with pressure. If your city water line is high pressure, don't crank it wide open. 

Good luck with the repair. Good thing is it's not a show-stopper; meaning there are a couple work arounds to flushing the tank. But as mentioned previously, it's new and should work as designed. Don't recall off the top of my head when mine was built but likely in or around the same time frame as yours.

Have you made the Air8 repairs to the vents? Mine were already in place which leads me to think my unit was built fairly late in the 2020 build cycle. 

Raydar

Thanks Airboss, I purchased our 400 in late October. And the Air8 mod. Was completed by Nucamp at factory. 

AirBoss

Yessir. Purchased mine in early Dec so we're peas of the same pod more or less. Cheers!

Denny16

This is strange?  NuCamp has been using this back flush system since 2018, I have a December 2018 TaB400, back flush system works great.  This was not a new mod in 2020, someone was either not paying attention.
cheers

AirBoss

Can't say what or how but its an issue for some T@B400 owners. I'd like to think a QC systems check prior to shipment would catch this, but fortunately its s fairly easy fix.

anba

We have a 2020 T@B400 BDL and we have the same black tank issue. Nucamp confirmed that they had a "few" units with the backward install and that swapping the hoses is the solution. I'm fairly new to the T@B so my question may sound naive, but wouldn't it be better to correct the problem by reversing the wrong install instead of cutting and splicing two hoses which introduces two new weak points in the water system?

It's covered by the warranty, so I will let the dealer do it.

TNOutback

I had the same black tank flush issue.  I let my dealer take care of it over the winter.  When I got my trailer back, the outdoor shower assembly had clearly been pried and scratched out of the exterior wall, and only partially put back in place - with no caulking.  Later on we were fortunate to have a few days of unseasonably mild weather in early June, and went on a spur-of-the-moment trip; our first (and only) of 2020.  That’s when we discovered that the hot and cold water in the bathroom sink is reversed.  We really shook our heads at that, thinking back to our previous outings last Fall, not recalling that the water was backwards in the bathroom sink. Or was it? Oh well.   Now seeing pictures and understanding the procedure, it’s clear the less than capable folks who butchered up the exterior shower trying to fix the black tank flush, also left us the gift of reversed water lines! 

Oh boy.

AirBoss

@TNOutback
LOL! Could have been worse. Could have switched Black water lines for Bath sink lines! 

@anba
In theory yes, it's generally a better solution to reroute lines correctly as opposed to splicing them. I suppose you can request that from the dealer but the nuCamp recommended fix is to access the lines by removing the fiberglass bath sink component which exposes the flush lines and switch them, as shown below. It's an easy swap and you're off and running. If done correctly should be no problem. 

 

DINDAnLAN

We bought ours last November. Same issue here. Made factory aware of that and to get on the Air 8 list.

Denny16

Every time you splice a water line in a boat or RV, you have a potential leak/failure point.  But with pex water lines, you can use a Shark type connector, or a pex expanding connector, which is very secure when installed correctly.

I would not use hose clamps and barbs on a connection I can not quickly inspect and check.
cheers

TNOutback

@Denny16 I don’t think the black tank flush lines are PEX

Denny16

OK, I thought all the water lines were Pex.  On closer inspection they do look like garden hose tubes..
cheers

qhumberd

Thanks so much for the detail @AirBoss but I have one question about the routing of the black tank flush. I don't see in pic below the route to the wall and to the outside. Where is that? And where is this that in relation to the outside shower connections?

I am about to investigate a slow drip that seems to be coming from the outside shower area, but wanted to see where that was compared to this plumbing.

Thanks again

AirBoss

@qhumberd
Unfortunately I didn't follow the lines out past what is shown as nuCamp recommend just swaping the lines as shown. Sorry I can't add much there.

That said, the back flush connection is located immediately forward of the outdoor shower so I presume those lines pass thru the exterior wall in a similar fashion. I'd think by removing the outdoor shower panel you may get eyes on how the backflush it routed. 

As mentioned above, @TNOutback had an "interesting" episode related to this matter when his dealership attempted to fix the back flush issue by going thru the outdoor shower panel. Didn't end really well...perhaps he can add some color here? 

TNOutback

I suspect my dealer service didn’t know the proper procedure for the black tank flush fix, and just presumed they could access the reversed valve through the outdoor shower opening since it is close to the hose connection on the outside.  I would be hesitant to remove any outside fitting without first knowing what you will be able to access behind it.  Here I would lean on Creed at the factory to get his take on anything you might suspect could be happening in places you cannot see.  The dealer didn’t put the outdoor shower fixture back flush in the opening, and they inexplicably did not caulk it back up either. I could not move it any closer, and was afraid to take it out because it was in a bind and I was concerned about breaking it.  I just caulked it back where it is, with a rather unsightly gap to the wall.  I don’t know what you can access behind it.

Denny16

Sorry to hear about your poor dealer experience.

Cheers

qhumberd

Thanks @AirBoss and @TNOutback. I am doing some pressure testing with the water pump now that I am at home to see if there is a drop in pressure that will trigger the pump. It is fortunate that NuCamp put shutoff valves in the closet for both lines to the outdoor shower. I am checking one line at a time that way. So far no leaks noted by the wheel well outside and nothing noticed inside. Could just be another case of my 3 grandsons who beta test all connections, switches and latches as any growing boy should 

BTW would @TNOutback be able to share the name of the dealer? As we are both in middle TN I would like to know who to avoid for service. I think you can send a message to me directly on this forum.

anba

Just as a follow up. Our dealer reversed the wrong backflow installation. In addition we also had two loose connections at the back of the outdoor shower assembly which caused water to run inside to the back of the TAB when we used the outdoor shower.

Both problems were fixed under warranty, but could have been avoided with a better quality control and/or workmanship in the factory.

Denny16

Both of the hose connections shown in AiBoss’s photo go to the check valve, which is the issue, as the check valve is connected backwards. Not that the lines were wrong at the outside connection to the black tank flush inlet.  The white box the lines go down through cover the black tank under it.  The flush inlet connection is in the wall, comes up to the check valve and then back down to the black tank spray tube.  So there are no lines to swap at the inlet side.

This photo shows the two white tubes connecting to this black box behind the plywood support — this black bit is the check valve, water comes up from the inlet and then goes down to the flush tube/wand bit inside the black tank:


To fix this without cutting the tubes under the check valve as previously shown, you need to remove the black check valve (shown in the photo), and swap the connections on it by turning the valve the other way round.  To do this, you are going to have to remove the wood support bit that the valve is connected to it.

I finally worked this out, once the above photo was posted by @qhumberd.  What nüCamp could do is draw an arrow pointing up on the inlet tube and an arrow pointing down on the black tank spray end, showing the direction off flow, then the check valve should have an arrow showing which direction the water flows through it.

Production problem solved, that said, one tube is already marked with a blue stripe, but arrows make it easy to check the connection at a glance.
cheers

ecstatic

FYI the sink doesn't need to be removed to fix the black tank flush issue.  There is an access panel under the sink with four screws that exposes those hoses and allows them to be cut and corrected.