Omni/Magnitude Black Tank Flush Question

[psdtime]

On my 2022 Omni, there is a black tank flush in the wet bay. I'm not too sure how it's supposed to work, when I hook a hose up to it, it sound's like it's doing its thing. I'm not totally sure if I should have the tank drain open or closed, so I have tried both. My main concern is that when I take off the hose, the water shoots back out and dumps into my wet bay. It seems to me that there should be a check valve there. I'm not talking a ton of water, maybe .5 to 1 gallon. It's probably just what is in the pipes to the flush. Do those of you that have the flush encounter the same issue? Thanks

I just realized I put this in the Class B section, meant to put in the Class C section, not sure how to delete or move.

 

[16ACE27]

I moved your thread to the proper area.

A factory installed black tank flush should have two safeguards:
A check valve integrated into the water hose connection just like your city water connection, and;
A back-flow preventer usually installed in a wall cavity somewhere.

Thor has been known to install the back-flow preventer backwards in many Super-C RVs.. The amount of water that you get back out of the hose connection suggests that may be your case as well.

I recommend you get a clear section of drain pipe (or elbow) so you can see what's draining and verify that when you are putting water in the black tank via the flush, that it is coming out of the drain.

 

[Chateau_Nomad]

The instructions will state to leave the drain valve open the entire time. This is a CYA for the manufacturer, because people tend to walk away and forget the water is on and valve closed... DON'T BE ONE OF THOSE PEOPLE!!

The following has worked for me for over 5 years:
Connect to sewer dump.
Open drain... allow tank to fully drain.
Hook up hose to black tank flush.
Close drain.
Turn water on an monitor tank fill...
DO NOT WALK AWAY!! NO MULTITASKING!
Fill tank to about 3/4 full.
Rock the motorhome to slosh water in tank.
Pull drain valve and allow to drain
Close valve.
Repeat the fill... rock... drain above.
Turn off water.
Wait about 5 minutes for pressure to release.
Close drain valve
Remove hose from tank flush connector
Remove, flush and stow sewer hose.

This has worked perfectly for me. All my tank sensors work fine.

 

[psdtime]

Thank you both! I'm at least sure that the check valve at the water hose connection is either inoperative on simply not there. As for the directions, I completely agree with both of you. Thanks again!

 

[psdtime]

Confirmed, no check valve on my black tank flush, I threw this away and mounted a check valve model in it's place.

 

[EA37TS]

On my 2022 Omni, there is a black tank flush in the wet bay. I'm not too sure how it's supposed to work, when I hook a hose up to it, it sound's like it's doing its thing. I'm not totally sure if I should have the tank drain open or closed, so I have tried both. My main concern is that when I take off the hose, the water shoots back out and dumps into my wet bay. It seems to me that there should be a check valve there. I'm not talking a ton of water, maybe .5 to 1 gallon. It's probably just what is in the pipes to the flush. Do those of you that have the flush encounter the same issue? Thanks

I just realized I put this in the Class B section, meant to put in the Class C section, not sure how to delete or move.

None of my rigs have never had a check valve at the inlet. They only have a vaccum breaker in line which serves as a backflow preventer. Look at you waste water diagram.

 

[psdtime]

None of my rigs have never had a check valve at the inlet. They only have a vaccum breaker in line which serves as a backflow preventer. Look at you waste water diagram.

I believe you, but my issue was that the water was flowing back from the hoses and landing in my wet bay floor since it was the low point. I would be like a 1/2 gallon or so. Most of the time when I was flushing the black tank, it was right before I plan to store the rig, so I would have to towel dry the wet bay floor each time and then leave it open long enough to fully dry before putting it storage. It was just kind of a pain. All I was hoping to do is to keep the water from flowing back into the wet bay,.

 

[The Gritz Carlton]

I never had that much water flow back out of that connector on mt 35SF but a little water spurting back is normal. Mine had two black tanks and they both did the same thing. My newer SOB does the same thing. Perhaps the hose from the connector to the tank is a bit longer with a dip in it and this causes a siphon back. If it works I wouldn't mess with it. Just get a small pail/coffee can and catch what you can, dabbing the rest of it up with a towel. The benefit of a clean tank far outweighs the effort. I would remove that check valve. If one was suppose to be there, it probably would have one there. I agree with Post #3....run as much water through as you wish but never leave your knees when doing so. It's like leaving bacon frying in the pan...it knows when you're not looking and it will win the battle of common sense.