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Old 07-18-2016, 12:38 PM   #11
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I have had 2 of the plastic valves go bad (did not let any water go through). One RV repair place gave me a 90 degree connector saying they do not sell the valves any more, they just get rid of them. They said they have seen too many failures (which usually flooded the trailer and caused a lot of damage). They said I was lucky it failed closed. I have since gotten a brass valve which seems to work better. Get a 90 degree connector to see if the valve is the issue.

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Old 07-18-2016, 02:40 PM   #12
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Originally Posted by jtstromsburg View Post
Not too uncommon to find the check valve installed backwards. I know you said you just changed that but might not hurt to make sure.
It's about gotta be that or the whole hose is plugged at the spray end. In which case case you'll have to gain access to where it attaches to the tank.

X2 on the backwards statement ... several XLR guys on the forum have found the check valve backwards from the factory. Mine was making all kinds of noise and preventing good water flow, so mine went bye-bye... what do you need a check valve on a black tank flush for anyway? It would take two failures at once to possibly cause a black flow situation. And, you would be not following instructions (whatever the heck they are!)

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Old 07-18-2016, 06:05 PM   #13
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may I ask a question related to this? As I was flushing my black tank the other day I had a thought. is there a back flow preventer built in or am I chancing that I am polluting my fresh hose supply. I am hooked up to water supply with my fresh hose and then I am running a garden hose off the same spigot ( a tee) and this to the black tank flush. or should I be buying something to prevent this? thanks
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Old 07-18-2016, 07:00 PM   #14
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There is a back flow preventer on the vacuum break
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Old 07-18-2016, 07:31 PM   #15
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thanks for the come back. now I can breath, or I mean, drink better
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Old 07-18-2016, 07:44 PM   #16
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Originally Posted by Drrayrn View Post
thanks for the come back. now I can breath, or I mean, drink better
To ensure you can always breath, buy a second hose (different color is best) and use it exclusively for your back flush process!
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Old 07-18-2016, 07:57 PM   #17
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Originally Posted by RSchleder View Post
To ensure you can always breath, buy a second hose (different color is best) and use it exclusively for your back flush process!
I agree with this but remember if your water pressure is 45 PSI positive side it's not going to contaminate your hose. Also you should be leaving your valve open when in use by the directions. So no back flow through your hose but it's always best to use to different hoses... PS: but I also use bottle water not nothing from my hose.
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Old 07-18-2016, 08:51 PM   #18
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Is it normal for the backflow preventer (i assume that's what is up under the bathroom sink??) for my black tank flushes to make loud vibrating noise when in use?
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Old 07-18-2016, 09:19 PM   #19
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Black tank flush not working

I had a problem once which was I had my pressure regulator connected while trying to flush tank. Very little water was going to tank. Took off regulator and problem solved. Must have built up more than 55psi and shut down the flow. Regulator had worked fine all weekend and all camping trips since.

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Old 07-18-2016, 10:28 PM   #20
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This was my experience with the black tank flush...I hooked up the hose to the exterior connection. Turned the water on. After a while I opened the sewer hose to drain the blank tank. Nothing. I wondered where all the water went. Looked in side the RV and saw water running out from the sink cabinet. Cleaned that mess up and looked for answers. It was suggested that I bang on the vacuum breaker. I gave it several good hits with a wrench. I also hooked up my air compressor to the black tank flush exterior connection and let the air pressure blow out any obstructions. Hooked water hose to the flush connection again and voila...success. It works now. This may or may not work for you. Just letting you know what I did.

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black, black tank, black tank flush, tank

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