Black Tank Flush System

[Dave49]

A new problem has come about that I have never heard about. Dumped my black tank and when I use the hose for back flush there is a lot of back pressure and it doesn't seem to be working. Sometimes I close the black tank valve for a few to put enough water in to gety a good flush. While doing this either with the black tank closed or opened I get a high pitch sound and my dog and cat go crazy it hurts there ears so bad. But last night while doing this I happend to look under the trailer and there it was, the underbelly cover sagging from you guessed it, water! I poked a hole in it to get rid of the water as it has been raining hard here for the last 12 hrs at least and wanted to get the water out of there quick as I could. Black tank seem to dump well, and I been using chemical constantly. I have flushed a lot of water down and it doesn't change it. It acts like it's plugged, but I don't know how it could be.

Any ideas on what may be happening? When the rain quits I will be under there dropping the underbelly so I would like to know if there is anything I should be looking for.

Thanks
Dave

 

[cookie]

I would start by looking behind the inspection port located in the shower.
Behind it you should see the PEX plumbing for the shower and some plumbing going to an anti-syphon valve.
That valve may have cracked or otherwise failed.
Turn your flusher on and observe the anti-syphon valve.
I would also look behind the UDC for any leaks where the city water hooks to the flusher line.
Please let us know what you find.

Peace
Dave

 

[JohnDar]

Depending on your floor plan, the anti-siphon valve might not be located at that shower wall port. You may have to remove the basement wall to locate the lines to it. That will also allow you to inspect for any water damage if it is leaking. While you're in there check the location of your converter and move it if it's near that line.

 

[Gary521]

There should be a check valve in the black tank water flush line. Could be installed backwards. This happened to a friend of mine.

 

[TXTiger]

Does the sound happen when you dump the gray tank or only when dumping the black? If only the black then I bet there may be something wrong with the anti siphon valve

 

[guyc66]

A new problem has come about that I have never heard about. Dumped my black tank and when I use the hose for back flush there is a lot of back pressure and it doesn't seem to be working. Sometimes I close the black tank valve for a few to put enough water in to gety a good flush. While doing this either with the black tank closed or opened I get a high pitch sound and my dog and cat go crazy it hurts there ears so bad. But last night while doing this I happend to look under the trailer and there it was, the underbelly cover sagging from you guessed it, water! I poked a hole in it to get rid of the water as it has been raining hard here for the last 12 hrs at least and wanted to get the water out of there quick as I could. Black tank seem to dump well, and I been using chemical constantly. I have flushed a lot of water down and it doesn't change it. It acts like it's plugged, but I don't know how it could be.

Any ideas on what may be happening? When the rain quits I will be under there dropping the underbelly so I would like to know if there is anything I should be looking for.

Thanks
Dave

Dave,

I had this same issue with my blank tank flush when I first got my 5er. Serious back pressure with a high-pitched whining noise when trying to flush the black water tank. I first removed the anti-siphon valve to see if it was defective. It appeared fine with no blockage so I figured it had to be something in the line. When I opened up the panel to look behind the UDC I found that the flush line had a good kink in it caused by a plastic zip tie that was holding it in place. I cut off the zip tie and straightened the line as best I could and tried the tank flush again......viola, it worked great. If your tank flush has never worked then I would recommend checking for a kink in the line.....may be a simple fix like mine.

Guy

 

[03svtcobra]

I would start by looking behind the inspection port located in the shower.
Behind it you should see the PEX plumbing for the shower and some plumbing going to an anti-syphon valve.
That valve may have cracked or otherwise failed.
Turn your flusher on and observe the anti-syphon valve.
I would also look behind the UDC for any leaks where the city water hooks to the flusher line.
Please let us know what you find.

Peace
Dave

I have a 2005 Landmark Monticello. My anti syphon and check valve were located in the coat closet next to the front door. This closet has the systems monitor and other controls in it too. I took out the removable panel and there they were.

 

[Ray LeTourneau]

Could the valve possibly be installed backwards? Or is it safe to assume this isn't the first time you've used the flusher? It sounds like a failed valve for sure.

 

[Bobby A]

My anti syphon always has a high pitched wine to it and it has been working fine for the last 4 years of full time use, I've used it literally hundreds of time. Check valves do go bad, I've had to replace mine several times, I think its because of all the hard water at all the campgrounds we stay at. Every now and then I do get low pressure into the black tank flusher and when that happens I know its either the check valve or the screen is clogged. But for all your water pouring out under the underbelly I'm not sure about that, as others have said the first place to start in behind the UDC. JMHO Good luck

 

[wdk450]

That anti-siphon valve is a water damage accident waiting to happen. The way the valve is made there is an atmospheric port which CAN vent pressurized water, or the plastic valve can fail under pressure. This is the voice of experience talking - My valve failed due to suspected high water pressure in a park and soaked/destroyed my $250 power converter located under the valve in the utility compartment ( of course, this happened on the road at the beginning of a month long trip).

I would strongly advise replacing the atmospheric anti-siphon valve with a standard, brass, check valve.

Here is a link to the manufacturer's literature. Read item # 7. Note that the word is "Venting", not "normal flow". http://www.bandbmolders.com/files/TankFlusherInstructions2.pdf

 

[donr827]

Wdk450, The instructions from the manufacturer, #7, makes a lot of sense. There must be a reason why the trailer manufacturers do not follow the instructions from this manufacturer. It could be that other manufacturer of this devices might have a different view.
Don