Black tank flush questions

[Mikendebbie]

We have been full time in our new 3921FB for several weeks now. This unit has 2 black tanks - one for the front bath and one for the half bath. I flushed the using the black tank flush a couple of times. I have a single point of connection for the black tank flush in the docking station.

1. Does anybody know if the tank flush is supposed to flush both tanks? I just finished and only the front tank showed water coming out from the flush. After the initial drain for both tanks I turned on the flush and opened up each tank individually. No water came out of the rear/half bath tank - which indicates to me that the flush is not piped to that tank. Is this correct or is the flush piping kinked or maybe not connected? I do not see a second flush connection.

2. This is the 3rd RV I have had with built-in black water flush. I have never considered whether or not the black water flush piping requires a pressure reducer like the house plumbing. I have always connected a hose without a pressure regulator. Does anybody know if black tank flush needs to be on a pressure regulator or not?

[beeje]

My only suggestion would be that while you are flushing, listen carefully and you should hear the water entering the tanks. One is near the front and one towards the back.

[BB_TX]

If I felt the water pressure was high enough for the fresh water to require a pressure reducer, I would feel the same for the flush. Both use the same type piping and fittings.

[BuilderBob]

You don't need a regulator on the tank flush the more pressure the better as far as if it's to the rear black tank that would be a good question for keystone you would think it should be!

Bob & Carol
Washington St
2017 352RL 2008 Dodge 3500 DRW CC LB 4x4 6.7L

[Mr Pachu]

Originally Posted by BB_TX

If I felt the water pressure was high enough for the fresh water to require a pressure reducer, I would feel the same for the flush. Both use the same type piping and fittings.

X2 as mentioned above.

[DQDick]

I would be surprised if one inlet worked for two tanks for several reasons. I don't use a presure regulator on the black tank flush because since it is always open, there should be no pressure buildup to stress connections.

[Dave W]

I just use the same pressure (separate dedicated hose) that the rest of the RV water system uses which will usually have a pressure reducer at the CG spigot. Those tank flush devices have a couple built in ways of regulating pressure and maybe even be causing some water hammer. Those are the spray nozzle at the tank and a back flow preventer. Most if not all of that piping is PEX and unfortunately the lines are attached to the inlet fitting (plastic) and the nozzle (plastic) by a steel crimp ring which may or may not be well made up. I believe your owners manual will give you a max water pressure which IIRC, is about 50 pounds+/- and that's what you need to use.

I seldom use that built in flusher, instead use the one on the macerator or, if using a slinky, a Camco back flush fitting - both work better for our 5ers very slow black tank drain based on the added 'stuff' that comes out

[WeBeFulltime]

Originally Posted by BB_TX

If I felt the water pressure was high enough for the fresh water to require a pressure reducer, I would feel the same for the flush. Both use the same type piping and fittings.

Ding Ding Ding! This is the correct answer.