Black Flush Line - Shorten?

[howson]

Yet another "down under" related project and part of the soft hose replacement process. I figured this topic was worth it's own thread, thus here it is.

This time it is the black flush line. I have no intention of actually replacing the line but wanted it out of the way for other work. When I removed it from the back of the Nautilus panel and pulled the black water hose down under the trailer I got soaked with all the water in the line. I was surprised--I haven't flushed the black tank in months.

As I pulled (and pulled and pulled) the water line out of the camper's innards I eventually ended up at the bathroom knife valve. The flush line goes vertical at that point. My guess is this is where the atmospheric vacuum breaker/check valve is located. ( Diagram below is from Cate&Rob .)



The picture below is looking straight up from beneath the trailer underneath the bathroom. You can see the Bristol 1.5" bathroom gray tank valve. One black line is going up and one is coming down.




Look how close the black tank and flush connection is to the vacuum breaker location!


The connection on the Nautilus panel to the vacuum breaker is at least 1/2 the length of the trailer. Crazy long distance. No wonder water is retained in the line!



What I'm contemplating doing is relocating the black flush right below the vacuum breaker. The line will flush completely (like it should) due to gravity and the shortness of the line in this location. I don't like the connection on the Nautilus panel anyway, as when I disconnect it back flushes water into the compartment. Having a series of connectors to get a line outside is awkward and makes snaking a fresh city water line for water harder, too. (I know...1-800-Waaaaaa.)



I'll update this thread when I finalize the install with what I did. If you have a suggestion I'd appreciate reading it.

Also--if you don't winterize the black flush line--I suggest adding it to your regiment. May seem silly, and I know the water line will flex if frozen, but why chance it? Put a little antifreeze through the breaker valve and into the lines to remove all potential for damage. (Feel free to disagree--just my .02 based on what I found today.)

Howard

[Cate&Rob]

howson
Hi Howard,

Your pictures are somewhat confusing for those of us who don't know the physical layout relationship of the water panel, vacuum break and black tank flush nozzle on your trailer. Maybe a marked up layout drawing would help?

I think the gist of your message is to not expect that the flush line from the vacuum break to the tank will have a continuous downward slope (as it is supposed to). I can attest to this being the original situation on my 5th wheel, but I was able to better fasten the line along its original route to keep the downward slope as it should be.

Good advice (if you don't know for sure that your flush line completely drains from the vacuum break to the tank) to winterize this line with antifreeze. BTW, there are hand pumps for just this purpose.

Rob

[howson]

howsonMaybe a marked up layout drawing would help?

Sorry 'bout that. Does this clarify?

[Cate&Rob]

howson

Now this makes more sense (to me). On a 5th Wheel, the water panel is more-or-less under the shower and the black tank is under the bedroom. Completely different than your TT layout.

Rob

[howson]

8 Jun: This post is (almost) a duplicate of
https://gdrvowners.com/forum/operati...9930#post19930. I added it here, too, so this thread makes sense and is complete.
----------------------------------------------

If you have a Nautilus panel, you know the black tank flush connection is on the bottom right of the panel. The Nautilus panel in a 315RLTS is in the front pass-thru on the street side. The black tank is approximately in the middle of the trailer, so quite a distance from the black tank connection on the Nautilus.



If you've read through the thread at https://gdrvowners.com/forum/operati...e-in-a-315rlts you know from steve&renee's question and my subsequent answer (see post 23 in that linked thread) that if that black flush connection requires replacement it will be a tough task. From that conversation sprung the idea to move the black tank flush connection.

The first thing I did was cut off the white tabs on the back of the Nautilus panel that retained the connector and extracted it intact.

Using a 1/8" x 2" x 3' piece of flat aluminum I fashioned a mount that fits perfectly (~11.5" long) with one side resting on top of the trailer frame and the other on the top of the inside of the skirt. Then I bent a shorter second piece from the same piece of aluminum and bent it at 90 degrees. A hole was made in this second piece (prior to bending, actually) for the black flush connector. The two pieces are joined together with self-tapping screws which were then cut off flush.

The black flush is held to the aluminum with a 7/8" retaining ring. Pure dumb luck on my part that it all worked so perfectly. (I had the aluminum in my pile of "stuff" leftover from other projects.)



The aluminum was sanded, painted, and the black flush connection mounted just forward of the sewer connector after much consideration with self-tapping screws. Special consideration was made for the gas line, as I installed a clamp as a spacer to ensure there was no chaffing.

The black flush line goes up behind the shower (to the vacuum breaker) and then back down to the black tank. Where the flush connector is now, water has to travel forward just a short distance, then up into the vacuum breaker (that was left as originally designed and installed) and then down into the tank. (The latter parts are OEM.)

I tested the new setup and it works as expected. The best part is that when the water drains out of the black flush line (as it is supposed to do after a flush) the clean water drains on the ground instead of inside and on top of the drip panel (or whatever it is called) in the pass-thru.

Anticipating the question, I'm not too concerned about the connector getting damaged due to debris. Where It is mounted, it's aft of two large storage containers (I added them) so it is semi-protected. The likelihood is slim--I hope--that it will be damaged. If something does happen, I'm not concerned because this is a non-essential system that will be very easy to repair.

Here's what it looks like:






Any questions...fire away.

-Howard

P.S. Using a pex connector on the black hose...yes, I know that is wrong, Rob. I'm not too concerned with that connection on this system. I used the parts I had on hand!

[315RLTSinPA]

I never understood why they put the tank flush connection all the way up at the nautilus panel for a travel trailer. Besides, who wants a flush hose inside your compartment next to all your other connections. You shortened your hose, I made ours longer. LOL I extended the flush hose back to the sewer outlet so dump station hoses could reach and I don't have to get my own flush hose out.

[Cate&Rob]

who wants a flush hose inside your compartment next to all your other connections.

The "logic" of putting the black tank flush close to the potable water connection is that the same hose is supposed to be used for either connection. A water supply hose should be attached to one or the other . . . but never both. A hose should NOT be connected to the black tank flush unless you are actively flushing the black tank. For the black tank flush vacuum break to work correctly, the hose must be disconnected when finished and the water in the line from the vacuum break to the inlet allowed to flow back out. On the tank side of the vacuum break, that water drops into the tank.

If used correctly, there is no way that the black tank flush becomes a "contaminated" connection. If a hose is left connected to this port and the vacuum break cannot drain the line, there is the possibility of contamination. One of the most common "mis-understandings" at any campground is the two hoses (one for potable and one for black tank flush) attached to the camper and running back to a Y connection at the post. Both left connected and full of water. Then, the owner turns off the faucet when they leave the camper. Now the black tank is connected (through the two hoses and the Y) to the potable water intake. The length of the two hoses is not a limitation for bacteria in stagnate water.

Just use one hose and connect it to either the potable water inlet or the black tank flush. With only one hose, you can never make a mistake.

Rob

[boyscout]

I made ours longer. LOL I extended the flush hose back to the sewer outlet so dump station hoses could reach and I don't have to get my own flush hose out.

https://gdrvowners.com/forum/operati...ack-tank-flush

[boyscout]

Yet another "down under" related project and part of the soft hose replacement process. I figured this topic was worth it's own thread, thus here it is.

It seems that one of the stages in Grand Design's design process is, "Give Howard something to work on". Or maybe it's, "Try this, then watch what Howard does to make it better." You are worth twice what you're paid sir.

[howson]

It seems that one of the stages in Grand Design's design process is, "Give Howard something to work on". Or maybe it's, "Try this, then watch what Howard does to make it better." You are worth twice what you're paid sir.

Thanks for the kind words, Mark. But anything times 0 is still 0. (All of your moderators are unpaid volunteers.)

[bogen2]

The "logic" of putting the black tank flush close to the potable water connection is that the same hose is supposed to be used for either connection. A water supply hose should be attached to one or the other . . . but never both. A hose should NOT be connected to the black tank flush unless you are actively flushing the black tank. For the black tank flush vacuum break to work correctly, the hose must be disconnected when finished and the water in the line from the vacuum break to the inlet allowed to flow back out. On the tank side of the vacuum break, that water drops into the tank.

If used correctly, there is no way that the black tank flush becomes a "contaminated" connection. If a hose is left connected to this port and the vacuum break cannot drain the line, there is the possibility of contamination. One of the most common "mis-understandings" at any campground is the two hoses (one for potable and one for black tank flush) attached to the camper and running back to a Y connection at the post. Both left connected and full of water. Then, the owner turns off the faucet when they leave the camper. Now the black tank is connected (through the two hoses and the Y) to the potable water intake. The length of the two hoses is not a limitation for bacteria in stagnate water.

Just use one hose and connect it to either the potable water inlet or the black tank flush. With only one hose, you can never make a mistake.

Rob

So if you can safely use your fresh water hose to connect to the black flush, what about connecting the outside faucet to the black flush and use the water pump to flush with water from the FW tank? That would be very handy when at an RV dump that doesn’t have water for flushing.

Bob

[Cate&Rob]

So if you can safely use your fresh water hose to connect to the black flush, what about connecting the outside faucet to the black flush and use the water pump to flush with water from the FW tank? That would be very handy when at an RV dump that doesn’t have water for flushing.

Bob

Hi Bob,

There would be nothing wrong with this. In fact, I do this when I want to flush the back tank with warm water or when I have to use a dump station. The only thing to remember in this plan is that all water connections at your trailer must remain sanitary. Don't hook up the flush connection to an unknown hose at a dump station. The water hose at a dump station is usually labelled "unpotable" . . . so, you have no idea where that water is coming from.

Rob