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Old 11-01-2021, 01:17 PM   #1
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Black tank valve question.

I have a 2022 coachman freelander 27QB motor home. The pipe coming out of my black tank has a open and close valve at the end to dump it but right at the beginning of the black tank there is a valve shut off at an elbow. What is the purpose of the second shut off valve?
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Old 11-01-2021, 03:30 PM   #2
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This just came up a few weeks ago on another model. It's to keep the waste in the tank instead of the pipe. A number of units have this setup.
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Old 11-01-2021, 04:30 PM   #3
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Originally Posted by dizcom View Post
This just came up a few weeks ago on another model. It's to keep the waste in the tank instead of the pipe. A number of units have this setup.

So they don't trust the pipe? Sounds funny. I think most rigs have their gate valves at the termination (cap)- mine included.
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Old 11-10-2021, 04:50 AM   #4
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My rig has this on the black tank also. It was suppose to have one on the grey tank too. I installed one. With tank heaters this will keep the water out of the discharge pipe so it won't freeze and burst. This is for winter. Also if you hit the discharge line which hangs low hopefully you won't get a tank full of poo!
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Old 11-10-2021, 08:55 AM   #5
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I have the same valve setup. I agree with dustydave.

I close mine after the last dump of the year. I figure when I add pink stuff to the black tank. Some of it goes into that short pipe from the tank.
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Old 01-27-2022, 02:30 PM   #6
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If you have road hazards that might rupture the cross over pipe from the waste tank, you wonít spill raw sewage on the ground. Itís a pain to open and close both valves each time but I added an extender to mine so I donít have to crawl under the unit.
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Old 01-28-2022, 12:57 AM   #7
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Some RV have DUAL GRAY (kitchen) tanks, some a tank is on opposite side from dump, with EXPOSED PIPE (like you have?). LARGE valve is always BLACK, smaller is GRAY. ALL VALVES should be CLOSED during travel, because wreck, road debris, or a blown tire = broken pipe= BLACK TANK DUMP/ LEAK can be a FED offense/first response agency reportable under CWA (Clean Water Act); valves at the tank can contain/ prevent leak w/ PIPE= broken. Internet can show many broken Rv pipes on roadside. Leak prevention= Best. p.s. MY rig/floorplan, by contrast, waste piping is less than two feet length black and gray, and contained/ protected
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Old 01-30-2022, 04:04 AM   #8
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The first valve at the tank also seems to helps prevent clogging. If you only had the one valve at the sewer connection, stuff could settle in the pipe until you decide to empty the tank. Then there is less force to actually flush because the pipe is already full. Low temps could also freeze the pipe.

My routine is to connect to the sewer hose and leave the black valve open at the sewer connection. When the tank is full, I open the black valve at the tank. Gravity does its job and just about everything is flushed out. After the black is done, open the grey to rinse out the sewer hose. Close the black at the tank and then the gray at the sewer connection when done. If we are at a spot for several days I do sometimes leave the gray open until the second to last day. Let it fill up the day before we leave, so it can rinse the hose.

It wasn't obvious to me when I first bought my RV... Don't think you can leave both black valves open all the time. Black tank water will drain easily. Toilet paper and crap will just settle in the tank. It'll most certainly clog.
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Old 01-30-2022, 06:07 AM   #9
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I have the 28Z model and the black tank line goes from one side of the RV to the other (under the drive shaft) Thats said, the valve coming directly out of the black tank needs to ALWAYS be closed until you go to dump, otherwise the solids will build up and cause a blockage. ALso in case it gets broken while driving it will not dump the entire black tank load.

I sometimes wonder if installing a macerator at the black tank then using a small detachable hose when draining the tank would be better. Just tire of spending money I guess keeps me from doing it.
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black tank, tank, valve

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