Black water tank flush spit back at me.

[kenandterry]

I connected my DIRTY JOB hose to the black water tank flush connection on my Georgetown. It has been giving me increasing troubles, but today, here’s what happened.

I connected the hose to the flush connection, black tank waste valve open, I turned on the water tap .....good pressure from campground taps. I know the water filled the hose into the connection, but didn’t hear anything after just a few seconds. No sound of water flowing, no black tank wand spinning......like once upon a time. I turned off the tap. When I disconnected the hose from the connection, the pressure of the water from behind the connector came out and sprayed me quite well. Slight odour of sewer, but nothing disgusting.

How do I determine if the back flow preventer is the culprit, or the wand is completely plugged.....either of which will not let me use the black flush? In my Georgetown the back flow preventer is up underneath my bathroom sink and is the clear plastic model with 90 degree input/output connections.

Thanks

[Skip12]

If you can find someone to help, you could try to disconnect the anti-sipon valve from the output side, put it.in a bucket and turn the water on for a second to see how the water flows out. I suppose you could build connectors to bypass the valve to see if that works.

If it were me, I think I'd just replace the valve and hope for the best.

[emm-dee]

I had a similar problem when the cheap B&B 571 “backflow preventer” failed. Seems as though some plastic shrapnel from the valve got pushed into the actual flush fitting. Easy fix. Here’s the head about it.

http://www.forestriverforums.com/for...rn-189905.html

[nomad297]

If the problem was a clogged sprayer, the back pressure would relieve itself at the vacuum breaker dome, and you would see the (minimal) water there, only once the city water side’s pressure has been eliminated. If the problem is a clogged vacuum breaker where the check valve diaphragm is stuck closed, you would see water where you have described. However, in the unlikely case where the vacuum breaker’s check valve is stuck open and forcing the air inlet cartridge to stick closed AND the jet is clogged, you could be seeing water blow back as you described.

Your problem is with the vacuum breaker — not with the black tank sprayer...unless all of the planets are aligned just right.

Bruce

[fonzie]

I would attach hose to black water flush and let pressure on for 15 minutes. If the sprayer is clogged, it will take time for the clog to soften up and flow again. Have the black tank valve open all the time and wait.

[emm-dee]

Originally Posted by fonzie

I would attach hose to black water flush and let pressure on for 15 minutes. If the sprayer is clogged, it will take time for the clog to soften up and flow again. Have the black tank valve open all the time and wait.

I think it depends on what is clogging the flush. The outlet which is made by B&B has 12 holes, each one 1/16” in size. In my case there were tiny chunks of plastic and glue that had accumulated in enough volume to completely clog most of the holes. I can’t say where the debris came from. The vacuum valve was leaking so it’s possible the junk came from the actual valve. Since we’re all familiar with Forest River’s dedication to quality control maybe some glue got into the system.

All I know is once the vacuum valve was removed and the flush outlet replaced everything started working as it should.

[nomad297]

Originally Posted by emm-dee

The vacuum valve was leaking

The vacuum breaker probably wasn’t leaking — if the spray nozzle gets clogged, the atmospheric vacuum breaker will relieve the pressure between the vacuum breaker and the nozzle, which results in spillage from the vacuum breaker dome. It was probably doing its job.

Bruce

[emm-dee]

Originally Posted by nomad297

The vacuum breaker probably wasn’t leaking — if the spray nozzle gets clogged, the atmospheric vacuum breaker will relieve the pressure between the vacuum breaker and the nozzle, which results in spillage from the vacuum breaker dome. It was probably doing its job.

Bruce

Vacuum valve was definitely leaking. When water supply turned on there was a steady stream of water bubbling out of the top of the valve and running out the bottom of the MH.

After replacing the vacuum valve the flush outlet was working, although very slowly. After about 4-5 fills the system completely stopped. I removed the vacuum valve, verified water flow up to that attach point and then installed the PVC elbow to bypass the vacuum. I then removed the outlet thingy and found the debris clog.

Did the valve fail and then cause the clog, or did the clog cause the valve or fail? Don’t know and since everything works now don’t care.

[kenandterry]

I appreciate the feedback and info so far.
We’re on a road trip for the month and I’m not going to temp fate, nor do I have all my tools available to investigate this further right now.
I’m using the hose attached wand to power rinse the black tank down through the toilet, so there’s no real problem other than convenience of the OEM black tank flush method.
I’ll update when I tackle this further.
Thanks for now.