Black tank flush clean out

[rjt30114]

Neither of my black tank fresh water flush ports seem to be letting fresh water in the tank to clean it out. They just build up pressure and nothing goes in the tank. Then when you unscrew it spews all the fresh water back out. This is on a 2022 BT36 and is the same for front and back bathrooms.

[Judge]

It is possible that they installed the vacuum breaker backwards or they did not cut the hole in the tanks for the water to flow in from the San-T-Flush port.

Neither would be surprising when it comes to Thor.

I would get out your schematics out and start tracing the plumbing….. or if its brand new, call your dealer.

[BaBa]

Our new Four Winds 31W came from the factory with this issue. Turned out the anti-siphon/back flow check valve was reversed plumbed - apparently a common issue. Warranty fix at dealer is your best bet unless you have the correct PEX tools and skills. In our 31W, the valve is located inside the wall between the bedroom and bathroom. It's up high in the wall, I'm guessing to mitigate any chance of blackwater infiltration and mitigate any potential siphon effect. Ours was accessible thru the far left cabinet over the bed, left side panel against the wall. If necessary, you can get to the PEX piping leading up to it thru the access panel within left nightstand or to a lesser degree, the access panel under the bathroom sink. I know this because I first tried cutting the lines below and inserting 1/2" PEX couplings to reverse the flow.





After reversing the lines, I tried another flush and water started pouring out of the coach onto the driveway. I discovered the water was coming from inside the wall flooding the bathroom floor! After opening up the side wall of the upper left bedroom cabinet to expose the valve assembly, I discovered someone at the factory had nicked the PEX at the valve with a hole saw

[sthursto]

Posting some pictures would be helpful.

[Tearstone]

This one-way valve is in the wall somewhere. Log into your owners portal for the schmatics document for your rig. It will detail exactly where it is located.

[BaBa]

I unsuccessfully tried to post pics before. Will try again here.

Here's the PEX supply and return lines at the bottom of wall, under the nightstand and bathroom sink:
https://drive.google.com/file/d/1-z9...ew?usp=sharing

After I cut and spliced them to try and correct the reversed flow:
https://drive.google.com/file/d/1FY2...ew?usp=sharing

Discovering the massive leak above inside the wall, I began to open up the wall above. Here's the check valve hidden inside the bathroom/bedroom wall, access thru left overhead cabinets over bed:
https://drive.google.com/file/d/1mRJ...ew?usp=sharing

https://drive.google.com/file/d/1mSM...ew?usp=sharing

https://drive.google.com/file/d/1VH3...ew?usp=sharing

And here's the finished job with a new 1/2" brass check valve and fresh PEX tubing:
https://drive.google.com/file/d/1PSC...ew?usp=sharing

Works like a champ now.

[16ACE27]

Originally Posted by BaBa

I unsuccessfully tried to post pics before. Will try again here.

Here's the PEX supply and return lines at the bottom of wall, under the nightstand and bathroom sink:
https://drive.google.com/file/d/1-z9...ew?usp=sharing

Here's the check valve hidden inside the bathroom/bedroom wall, access thru left overhead cabinets over bed:
https://drive.google.com/file/d/1mRJ...ew?usp=sharing
https://drive.google.com/file/d/1mSM...ew?usp=sharing
https://drive.google.com/file/d/1VH3...ew?usp=sharing

And here's the finished job with a new 1/2" brass check valve and fresh PEX tubing:

What you are trying to post as "images" are actually shared pages. You can post those links directly. They won't work in the image box or with IMG tags.

I fixed the links for you.

[wrapped]

Where did you get that valve and part number. Being full-time I've replaced those values multiple times and haven't been able to find a residential replacement only rv plastic type.

[BaBa]

I used a Watts LF288A anti-siphon vacuum breaker 1/2" brass, lead free and two 1/2" NPT male to 1/2" PEX adaptors (one with a 90-degree turn). Amazon has the valve here:

https://www.amazon.com/gp/product/B0...TUV3GW4L&psc=1

Good luck!

[wrapped]

Thanks

[Pete'sMH]

I simply bypassed the vacuum breaker altogether. I was able to use a shark bite one way valve to join the PEX lines in the basement where they went up to the valve and where they returned. I now have a much simpler, more direct flush system that can’t leak into the walls. I understand the code requirement for the valve but the risk of contamination is exactly zero so I’m not worried about it. I was so pleased with it on my class A after a messy flood that I did it on my new RV as soon as I bought it - before it could leak.