Black water flush not working?

Pixmap · 10-15-2022, 04:08 AM

Hi. I have a new 2023 (second day), and I am not confident my black water flush is working. I hooked up the hose and turned the water on.. nothing seemed to come out of the black hose? Also, a lot of water squirts out where the hose is connected to the trailer. Any thoughts?

Thanks

jxnbbl · 10-15-2022, 04:31 AM

I had the same thing with a brand new black water flush. First find the vacuum check valve. They will look something like this:

link

I have two of them on my trailer, one is under the bathroom sink and the other is hidden behind a panel inside the other bathroom cabinet.

There have been incidents where they put these on backwards...so there is no flow through.

In my case, this was not the problem the ptex piping had been crimped and the solution was to get to the crimp/bend cut it and insert an elbow at that location. I think during assembly they just forced the connection of that pipe putting a fold into the pipe.

jxnbbl · 10-15-2022, 04:32 AM

I should add that I actually found all the connections to "eliminate" the backflow valve out of the system. I did that to prove that wasn't the problem to the dealer as i was having a hard time convincing them it was more "internal" and to get it fixed under warranty

Pixmap · 10-15-2022, 05:33 AM

Thanks! I'll do some research today! Thanks

Pixmap · 10-15-2022, 06:19 AM

Looks like a lot of my plumbing is under the insulation of the camper... so I can't find any check valves. I guess it's a trip to the dealers. :-(

Again thanks for your help!

**chuckster57** · 10-15-2022, 06:24 AM

The anti siphon valve will be in the interior of the trailer not underneath it. Under the bathroom sink is one place, behind the shower faucet is another. It will have an arrow showing the flow path, and Im betting that its plumbed backwards.

**JRTJH** · 10-15-2022, 06:37 AM

Quote:

Originally Posted by Pixmap

Looks like a lot of my plumbing is under the insulation of the camper... so I can't find any check valves. I guess it's a trip to the dealers. :-(

Again thanks for your help!

Open the bathroom vanity door (under the sink) and count the PEX tubes you see. If there are two, they are for hot/cold water. If there are 4, then two of them are for the anti-siphon valve loop in the black tank flush line.

The actual valve will likely be "tucked way up near the back of the sink, about the same level as the faucet connections, so it may be "nearly impossible to see until you stick your head inside the vanity and look up, behind the sink".....

**sourdough** · 10-15-2022, 06:45 AM

Quote:

Originally Posted by Pixmap

Looks like a lot of my plumbing is under the insulation of the camper... so I can't find any check valves. I guess it's a trip to the dealers. :-(

Again thanks for your help!

It's not going to be under insulation. It has to be higher than the toilet so it will be inside somewhere and under the bathroom sink is the usual "hiding" spot. Don't know what trailer you have so can't look at the floorplan. Adding a signature as the forum rules state helps everyone help you.

Also, taking it back to the dealer to fix is going to be a huge waste of time and energy IMO. They might get to it in a week, maybe 2 months. It's a simple fix and won't take more than an hour of your time even if you've never done it before.

Gary R. · 10-15-2022, 04:21 PM

I gave up trying to find that backflow valve on our Alpine. The "Convenience Center" has a tank flush connection, but as more that one forum member has experienced, no flow was noted. I could not find the back flow valve under the bathroom sink (only two PEX lines there), or behind the shower faucet. I tried to trace the PEX pipe from the Convenience Center to the valve, but the pipe goes under the trailer to parts unknown.
Where the factory workers put it is a mystery to me.

So I just use a tank wand and back pressure water to clean the black tank.

Works fine for me.

**sourdough** · 10-15-2022, 04:59 PM

Quote:

Originally Posted by Gary R.

I gave up trying to find that backflow valve on our Alpine. The "Convenience Center" has a tank flush connection, but as more that one forum member has experienced, no flow was noted. I could not find the back flow valve under the bathroom sink (only two PEX lines there), or behind the shower faucet. I tried to trace the PEX pipe from the Convenience Center to the valve, but the pipe goes under the trailer to parts unknown.
Where the factory workers put it is a mystery to me.

So I just use a tank wand and back pressure water to clean the black tank.

Works fine for me.

Yours is probably a good fix if you can't find it. I've noted before of a friend that called a mobile tech because his failed and the cut the wall out of the inside of his pass through trying to find the lines/location - I like your solution better.

skids · 10-16-2022, 06:01 AM

About a check-valve: As I understand it, the place where the hose is attached to is like the city water supply with a check valve. You could attach a ball valve onto the end of the hose to shut off the water supply if you warry about backflow.

alnbobby · 10-23-2022, 09:59 AM

If you discover your black water check valve, and it's one of the black plastic types, be aware that they easily become inoperable (break?), especially if left in place during the winter. I've had to replace at least 2 of those valves in the past several years. One of my winterization steps is to remove the black flush check valve.

**flybouy** · 10-23-2022, 10:14 AM

Quote:

Originally Posted by alnbobby

If you discover your black water check valve, and it's one of the black plastic types, be aware that they easily become inoperable (break?), especially if left in place during the winter. I've had to replace at least 2 of those valves in the past several years. One of my winterization steps is to remove the black flush check valve.

If you're going to the trouble to remove then just replace it with either a metal vacuum breaker or with two 90° fittings and a shot length of pipe. If you use the second option then just use a backlog preventer on the garden hose.

maccam1 · 10-23-2022, 02:05 PM

i had this happen to me.in the check valve there was a stink bug that got up in there and was blocking the valve from working.

maccam1 · 10-23-2022, 02:07 PM

do you blow out your lines when you winterize,i attach the air hose to the black water flush,and blow it out real good.

SRD · 10-24-2022, 11:00 AM

Never used the black tank flush on my 2017 Passport and probably a good idea I haven’t. Doing some maintenance dropped the underbelly and the hose for the flush was way to long and kinked completely shut. That way from the factory

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