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Old 05-10-2018, 05:45 PM   #1
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Black Tank Flush - 2017 Chaparral 392

I was going to give our black tank a “Pre-season” flush as we had a few issues last year, I think mainly due to the 90 degree elbow. I noticed a sticker beside the panel stating something to the effect of “Ensure the fullthrough valve is open before flushing the tank” ....what the heck is a “Fullthrough Valve?” Is that the main dump valve or is there another valve I need to pay attention to???

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Old 05-10-2018, 06:05 PM   #2
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Iwould say it's the dump valve. They want you to leave it open when flushing.I don't because I want alot of water in tank when I'm flushing out the tank,You need the flow to flush out the tanks. Just don't leave it closed and walk off with the flusher running.It will ruin your day. I saw this first hand when my neighbor,at the campground did just that.Water,nasty water came up through the toilet.I believe his wife flushed the potty and it was pressurized pretty good.I could hear here screaming at him.Sounded like two drunk sailors cussing each other.

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Old 05-10-2018, 06:17 PM   #3
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They are taking about the dump valve, if you don't have it get a clear elbow so you can see how the flush is working
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Old 05-10-2018, 06:22 PM   #4
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Thanks everyone, that’s what I thought but I’ve never heard it called that before. I hooked the hose up but only let it run for about 30 seconds just to see if I could hear the sprayers going in the tank. Water was leaking from what hose connection so I might have to replace the washer.
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Old 05-10-2018, 10:08 PM   #5
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Before I had a flusher, I would use a back flush valve and fill the tanks to flush. You are correct, the flow really helps. Three fills and my guages would zero out.

Now that I have a built in flusher I am weary of full tank fills given all the extra plumbing related to the flusher (back flow preventer, etc.) Too many opportunities for leaks for my level of comfort.

I just run the flusher (w/water pressure regulator) for 5 min and confirm clear water coming out.
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