Nautilus P3 settings for Black tank flush

ColoradoSun

We used the black tank flush (along with the rest of the plumbing) for the first time a few days ago.  I had heard of some owners experiencing leaks so I had opened up the cover to be able to see inside of the Nautilus panel. I was under the impression that the water line from black tank flush inlet went directly to the black tank so I didn't think any changes to colored valves were needed. When I hooked up the hose from the hydrant and turned on the water the pressure regulator immediately began shooting out water. It appeared no water was going in but there were no leaks inside. I checked the Nautilus manual (should have done that first!) and the section on black tank flush on page 14, Step 3 a photo showed the colored valves set to the winterize settings. I changed to those settings and turned the water on and then could hear the black tank flush operating and discharge began flowing from the sewer drain hose. It was odd that the Nautilus manual does not actually say anything about setting the colored valve to the winterize setting for black tank flush and the photo merely infers it. I still can't figure out what is going on.
Did I do this correctly?

bergger

I used our black tank flush several times last year and don't ever recall having to move any of the levers.  The levers should only divert water coming in from the fresh water inlet, the white connection.  I remember just connecting the hose to the black tank flush and turning it on, water went right to the black tank sprayers.  Unfortunately as my 400 is still winterized I can't check this to confirm.  But that is how I remember it working. 

ColoradoSun

Yes that was what I expected too.  This morning I went back and opened the Alde compartment to get a look at the Nautilus plumbing. It sure looks like the line from the black tank rinse inlet has no connection to the colored valves before running into the compartment below the refrigerator and on, I assume, to the black tank. I have to try it again next time we're at a RV dump station.

Denny16

No need to wait until then.  You can test the flush system by hooking up a garden hose to the flush inlet, have someone watch from the toilet, while,you turn on the water and see where it goes.  Only takes a few seconds, the little amount of water you end up,with in the black tank will help the Happy Camper black tank additive keep your tank fresh smelling, even whilst you are not camping.
cheers

ColoradoSun

Denny16 Of course! Thanks for pointing out what should have been obvious. I'll check it this afternoon.

EricH

ColoradoSun said:

Denny16 Of course! Thanks for pointing out what should have been obvious. I'll check it this afternoon.

Any luck with this? We just tried using our black tank flush for the first time and had lots of water leaking out the bottom of our trailer. 

TomCanada

Just had the same problem when we went to use ours. Water came out the bottom but I could also see that it was leaking out from the bottom of the main surface of the Nautilus panel, just under the black tank flush inlet.  I looked under the bed when I got home and found the fitting to the inlet was a bit loose - I was able to hand tighten it another half to three quarter turns. I suspect that's where the leak came from but of course won't know until next time I try to use the flush.  Did you check yours @EricH and @ColoradoSun? 

Btw what's the recommendation for having Happy Camper in the black tank between trips?  I have the tank dumped and flushed but should input in a gallon of water + Happy Camper while it sits, and will it be ready to go next trip or will I need to add more?

ColoradoSun

After that initial use of the black tank flush it has worked fine. I never found any inside leaks and tracing the line coming in from the Nautilus black tank flush inlet confirmed there is no connection to any other water line. No separate settings of the colored levers for the black tank flush are required. 
I have read several recommendations from owners to keep some water mixed with Happy Camper in the black and gray tanks between trips. The Happy Camper instructions are one scoop with a gallon of water and then add two gallons for best results. We are trying that approach.

Denny16

Yes, their are no Nautilus valve settings for the Black Tank Flush, just connect, the hose and turn it on to flush the tank.  

From the Black Tank Flush fitting on the Nautilus panel, the water line goes back to the washroom/head to a check valve behind the wash basin pedestal.  Sometimes in the past, this one way valve gets connected the wrong way round, resulting in back pressure to all the flush system connections, and the flush does not work.  This also can cause a leak, when water comes out of the pipe connection on the back of the panel.
cheers

TomInPlymouth

On our maiden trip, with our 2021 TAB400 Boondock, we were having a fine time of our trailer until the black water tank flush.  Drained the black water tank, closed the valve.  Drained the grey water tank...closed the valve.  All was good.  Then I put a water hose on the flush fitting and turned it on.  I did not pressure reduce it on first try (only the water line is labeled as needing one, and the trailer comes with only one).  Water came pouring out the bottom like others have described.  It was NOT primarily behind the nautilus cover though a little was.  We sponged it out.  Most of the water drained from underneath and there was also some in the area under the passenger side bench.  Enough to bleed onto the inside floor.  We sponged and dried it all out. 

I drained the black water tank and tried it again with a pressure reducer at the recommendation of a service tech where we bought the trailer and same issue.

We removed the alde cover, the drawer under our refrig and can't see any problems with hoses, but it was wet and we sponge dried it out.

<How do I gain access to look behind the wash basin pedestal?>  I see that the pedestal has 4 "square" screws.  

I hope that provides access to the full water line.  I'll then try the flush hose again and if I have the whole length of the hose largely visible I should at least know what's happening

I was imagining I'd want to pull the bottom off to look at what happened, but that seems a little tricky.  Those self tapping aluminum screws look like they're dusty with "corrosion" and trying to remove the cover to look at things seems like pretty significant process.

Anyway, any help would be appreciated.  You can clearly see that I'm lost on next steps.
Thank you!

bergger

sounds like the sounds like the one way valve that is in-line with the black tank water line may be installed backwards. It’s a one way valve to prevent water from coming back down the line from the black tank. Others have had this issue and have had to have the valve removed and installed the right way. Maybe someone who has done this will chime in about it.

TomInPlymouth

Thank you.  It may well be. I see that the pedestal has for square screws holding the front panel on.  I'll pull them tomorrow and take a look.

I can hopefully see the full water line to the black water tank.  

Denny16

This is what you are going to find with the washroom sink pedestal removed.  The red arrows are the black flush water lines, the one way check valve is behind the plywood bit, circled in blue:


Since you have a 2021, this should be covered by your warranty, I would have the dealer check this out for you.
cheers
 

TomInPlymouth

Ours does look like that.  Ours has a small front panel that I removed.  Here are two photos.  I'll connect a hose to the flush outlet and see what happens...then I'll know what's what.  Thanks for the tip.  Very helpful.

Yes, it should be a warranty.   Our dealer already said that they can get to it in July (maybe)...and have not been responsive from the get-go.  Delivered the trailer to us 1 month after they received it and we saw it/paid for it...supposedly to prep for our taking it ..I have no idea what they actually did.  It hadn't been washed from the open trailer ride from Ohio to MA, inside was dirty from letting people tour our trailer, front window no longer stayed up, do not respond to questions about modifications we'd like or questions...on it goes.  I'll ask nuCamp for highly rated dealers that we maybe can use.

Denny16

Since you got this far, hook up the black tank flush inlet to a hose, and see if any water is going into the toilet black tank, by looking in the toilet flush hole (fresh water and pump off) and look for or listen for any sign of water running into the tank.  You should be able to hear this.  If not, then the check valve is connected the wrong way round (backwards).  

Factory solution is to cut the two lines midway, and reconnect them (with a push in connector) left hose to right and so on.  This will correct the wrong way round connection to the check valve.
cheers

TomInPlymouth

Yes, good plan.  We connected a hose to the black tank flush line and could see the full run.  Turns out that it was a leak right inside of the nautilus face plate...the first connection from the hose fitting to the inside line.  Was able to cinch it down and eliminate the leak (for now anyway.)  We ran the flush hose a bunch...made it to the toilet without a drop along the way.  

Denny16

Glad glad you got it sorted.  The leak behind the Black Tanks Flush line connection behind the Nautilus panel seems like a common issue mentioned here.
cheers

TomCanada

Just noticed this sticker in the Nautilus compartment.  Anyone know what this means?

Denny16

Probably referring to the holding tank gate valve, which needs to be open, to prevent overfilling the black tank, and flooding the wash room.
cheers

TomCanada

What's a gate valve?  Something user accessible?

Denny16

The handle you pull under the trailer to dump the black and gray tanks.
cheers

TomCanada

Ah ok I get it. I saw some videos of people filling their tank via flush with the valve closed to get it extra clean and always wondered if that had a higher than necessary risk of some nastiness if the level got too high - that video just recommended watching the black tank level on the panel. I feel safer just leaving it open and am ok if the inside isn't squeaky clean.  

Denny16

Yes, I agree, the flush unit is a jet spray wand inside the black tank, and squirts water down the sides to clean.  Leaving the gate valve closed, kind of defeats how it works.
cheers

manyman297

Just had this exact issue (loose fitting on Nautilus): 

https://tab-rv.vanillacommunity.com/discussion/comment/169424#Comment_169424

MuttonChops

TomCanada said:

Just noticed this sticker in the Nautilus compartment.  Anyone know what this means?

This comes up on lots of RV Forums.
As others have noted Fullway Termination Valve means the Black Tank Dumping Gate Valve
= = =
Copied from Google
    A fullway termination valve is a gate valve by its proper RV name. So they are saying that the black tank dump valve must be open during the use of the black tank flush system. This is so you do not have sewage blowing out the vent on the top of your RV, breaking the black tank or coming up through the toilet.

In other words just make sure your Black Tank Gate value is open {and connected to dump station  }

Denny16

MuttonChops, not likely to get an overspill from the vent, as the black and gray tank vents are tied together, and any black tank overflow is going to go into the gray tank first.
cheers

Verna

Thank you, @MuttonChops. I was beginning to wonder if my former 2019 T@B 400 was the only one with the warning tag to keep the black tank gate valve open and connected to the dump station while using the black tank flush. 

rs7971

Okay. We just took delivery of 2022 TAB 400 and wanted to try a short camping trip before winterizing. All went well until black tank flush. I followed the instructions to the letter and the towels on our shower floor got soaked and water flowed out the bottom of the camper by the driver side wheel. As I’ve had this for only a week, I was not about to take it apart to look for the problem. The good news is the dealer has our unit and is troubleshooting. I’m curious as to why this problem didn’t get caught during CQ check. It looks like I’m not the only one who experienced this problem.

manyman297

@rs7971 Looks like Nucamp still hasn't found a person who can reliably tighten water fittings yet . My guess is the black tank flush fitting on the backside of the Nautilus wasn't tightened from the factory. A lot of us had the exact same thing happen. I was lucky and ran across comments about it before we did our initial flush and was able to stop the leak before it really did anything. 

Also check your fittings under the kitchen sink. Our drain fittings were all loose and leaked gray water into the cabinet below. 

It's frustrating because these issues are proof that they aren't pressure testing anything (or at least not the black tank flush). Luckily these are the only two issues we've found with our plumbing in the first season camping. 

TABNewbies

@rs7971 and this is the loose connection that @manyman297 refers to:

Denny16

@manyman297, there is no way to pressure check the black tank flush, as their is no valve on it.  The flush is an open line, from,the Nautilus panel to the nozzle in the black tank.  Only thing in line is the check valve, which a pressure check would find only the check valve was installed backwards.  

cheers