Black Tank Flush Not Working?

TNOutback

Very strange.  I hooked up a hose to flush our black tank for the first time (after our 2nd camping trip), but no water flows when I connect a hose to the fitting and turn on the water.  I leave the black tank gate valve open per the instructions, but no water flows out of the black tank.  Ideas?

NorthIsUp

Do you hear water going into the tank. It should be a very prominent sound of the plastic black tank filling with water, especially if nothing is flowing out. 

Verna

I can hear the wand going around spraying the black tank walls, plus I can hear the water running through my sewer hose.

If you can’t hear it and there's no water coming out, I would say there’s an obstruction from the water inlet for the black water flush. 

falcon1970

How full is your black tank?  Do you use an aerobic product such as "Happy Camper" in the tank?  Do you get water through the sewer hose when you open just the gray water gate valve?  If there is only a little water in the black tank it may be that solids have dried out and dammed the exit.  If you don't get water from the gray tank drain the solids may be past the point where the two drains join.  Try adding water to the black tank along with "Happy Camper" or one of the other products like it.  Let it sit for a few hours and see what happens.  If just sitting for a few hours doesn't work you may have to tow the trailer for awhile to slosh things around in the tank.  BTW, keep the gate valves and the toilet flush valve closed while you are doing all this or you may have a surprise.
I have also seen a product from CAMCO that attaches to the drain Port at a 45 degree angle and to your sewer hose at the other end.  It has a hose connection that allows you to squirt water back up the drain ports into the tank.  I have never used one of these so I don't know how effective it is.

TNOutback

Black tank drains just fine when I open the gate valve.  I hear no spraying and no water flows out of the black tank when I have the flush hooked up and water is on. @falcon1970, ummm, no solids have been deposited in the black tank yet.  

ecstatic

I have the same issue with mine.  No water flows into the black tank from the flush, it is as if there is a plug in there.  I plan to have my dealership take a look at that and a couple of other minor things.

falcon1970

@TNOutback
OK, now that is a stumper!  It does appear that the flush port must be blocked.  There is a small screen inside the flush port connection.  Might that have debris (or something) covering it?  The screen can be removed and back flushed if there is debris covering it.  

TNOutback

falcon1970 said:

@TNOutback
OK, now that is a stumper!  It does appear that the flush port must be blocked.  There is a small screen inside the flush port connection.  Might that have debris (or something) covering it?  The screen can be removed and back flushed if there is debris covering it.  

No debris in screen.  With hose connected and water on, nothing happens.  When I turn the water off and go to disconnect the hose, the water is definitely under pressure as it sprays everywhere when I’m unscrewing the hose.  Definitely blocked.  The only way I can see to get to the inside of the fittings to take a peek is to remove the bathroom wall unit.  I’m not doing that!  I’ll add it to the unfortunately long and growing list of problems with our new T@B.

falcon1970

@TNOutback
So definitely a blockage, but somewhere in the piping.  Sounds like warranty work.  I don't think I would want to tear into the bathroom wall either but maybe nuCamp can provide us some guidance as to how the panel below the sink is attached.  Looks like several screws with decorative caps but there are likely some hidden connections as well.  And I don't know that I would trust a dealer to do it either.  At least if I do it I can be assured that I won't destroy something.

TNOutback

My guess is that there is a back flow preventer installed in that line, and someone installed it backwards!

ScottG

@falcon1970, I have no firsthand knowledge of the 400 anatomy, but you are probably onto something with the decorative caps. If they are like most others I've seen, the caps should pry off and then you can remove the screws. If it's truly an access panel (which it sounds like it is) there shouldn't be any hidden connections.

I agree with you about giving it a go yourself. Even if you do damage something, it's less frustrating that having some disinterested ham-fisted tech damage it for you!  ;-)

Michigan_Mike

TNOutback said:

My guess is that there is a back flow preventer installed in that line, and someone installed it backwards!

I would guess that these units are a one-piece device with a spray nozzle head on them as you can hear them working when hooked up to a water hose.  I would screw in a brass RV blow out valve and try using an air compressor to see if that would remove any debris in the nozzle.  I could see a nozzle possibly plugging up over time from debris within the tank, but this is unusual I’ve it’s a brand new system.  It sounds like a defective part from the manufacturer and probably slipped down the assembly line when the crew went to lunch.  😀

falcon1970

Oh dear, now I am curious.  I guess I will have to investigate how that panel is attached--and detaches.

gspdx

So I have another question.  Over the course of this summer I only found one dump station where the hose had a threaded end that would screw in.  I have found some with a cut off hose and some with a pipe that functioned as a nozzle.  I did buy a Camco water bandit to help on cut off hoses but this seems a little strange to me.  Is this normal all over or have I just been "lucky"?

Verna

@gspdx, this is “normal”. 

DeanP

We just tried our black tank flush for the first time this morning and we have the same problem - it wouldn't take flow.  I think @TNOutback nailed it.  I'm sure this type of connection requires a back-flow preventer.  I would imagine the same person installed them on all the 400s.  Once the first one went on wrong, all of the rest followed suit.  I wouldn't expect that this system would be factory tested, so there was no way to catch the mistake.

TNOutback

I did exchange email on this with Nucamp. It’s not unheard of these being installed backwards from the supplier. 

ecstatic

TNOutback said:

I did exchange email on this with Nucamp. It’s not unheard of these being installed backwards from the supplier. 

Did they recommend a way to fix this?

TNOutback

ecstatic said:

TNOutback said:

I did exchange email on this with Nucamp. It’s not unheard of these being installed backwards from the supplier. 

Did they recommend a way to fix this?

They said it’s a dealer fix. 

DanL

I had the same problem.   I took it to the dealer and they determined the back flow preventer was installed backwards.   Unfortunately, they had to access the back flow preventer from the inside of the trailer which takes labor.    Fortunately, it was covered by warranty.  Works great now.

AirBoss

Yep...same here. First trip. No solids in black tank. Water flowed from under trailer,  not out the hose. Seems odd that a QC check didnt catch this at the factory. Waiting on NuCamp to advise dealer on repairs process. Not a show stopper but should function correctly out of the factory. 

qhumberd

For those with the T@B 400 I wanted to share the location and plumbing of the backflow preventer for the black tank and the way to access. Mine was working fine but as my sink was defunct it had to be removed so that opened the location. You might be able to reach the spot where the valve is located behind the plywood without disconnecting the sink but it would be tight. I was pulling the sink so it has been removed to allow a better view of the area.

In this picture the hose on L is the input from the black tank flush connection on the outside. Flow goes up to the one way vacuum breaker and then down to the black tank, where it sprays. This is loud and quite easy to hear when it is working.

The valve is pictured here from above behind the plywood bit. Note again flow going up the bottom hose and out the 90 deg connector back down to the hose to the black tank. These are simple 1/2 in pipe connections.



These are shots from the Amazon page which shows the identical valve for a better view.



These are around 26 dollars at Amazon if a replacement is needed, and the fittings look easy to remove and replace. If it is plumbed backwards as some have noted, I think there is space to swap the lines at the valve without having to cut anything and that should get it working.

My final observation would be to suggest that water could stay in the valve so as part of winterizing the trailer it seems prudent to use compressed air to blow out this valve and remove any residual amount that might freeze in the valve body. I have added that step to my winterizing checklist as I saw mentioned by @ADRawli.

As I am learning the nuances of our little home I find it helps to see what is "behind the curtain" to help understand function and fix malfunction as camping season is upon us.

Best wishes all