Maiden Voyage - Tank Flush not Plumbed Right ???

[Old-Biscuit]

Originally Posted by winniman

Cant believe some of the stuff you see on new units anymore. No wonder the chinese are taking over. What ever happened to pride in workmanship.

'Piece Work'

"Hey gang, we have 12 units on the schedule today. Knot them out by 12:00 and we all can go home. Get set----GO!"

[dabrooks]

Originally Posted by mrf1002u

So after a little looking, this is my plan to eliminate the BFP in the wall.

I am going to cut the 2 blue PEX pipes off in this pic just below where they go up into the wall cavity.

https://www.dropbox.com/s/ehx1qahanz..._0976.JPG?dl=0

I'll pick up two of these Sharkbite elbows from Lowes, and a short stick of blue 1/2" PEX pipe and make a bypass. This will also eliminate having the two threaded connections from the original BFP up in the wall. (Instead of dropping them down and using those existing threaded connectors on either end of a PVC bypass.)

https://www.dropbox.com/s/2luuqlf90i...elbow.jpg?dl=0

Larry W.

Make sure you put a shut-off on the black tank flush inlet where the hose connects so you don't get any odors from the black tank in your wet bay. I did not put a back flow preventer in my line because I did not want to trap water in the flush line. I may try to take a photo later to show my hook ups.

[mrf1002u]

Originally Posted by Old-Biscuit

'Piece Work'

"Hey gang, we have 12 units on the schedule today. Knot them out by 12:00 and we all can go home. Get set----GO!"

LOL

[mrf1002u]

Originally Posted by dabrooks

Make sure you put a shut-off on the black tank flush inlet where the hose connects so you don't get any odors from the black tank in your wet bay. I did not put a back flow preventer in my line because I did not want to trap water in the flush line. I may try to take a photo later to show my hook ups.

Sounds like a great idea.

Now thats a REAL back flow preventer!

Should be easy enough to add to the blue pex pipe or the screw connection where the flush system soft line connects to the blue pex hard line; both on driver side.

Larry W.

[4x4van]

How about making up a new BFP assembly, with 2 short (maybe 18-24") lines. Then, using sharkbite connections where you plan to install bypass, instead install the new "assembly" sticking up into the wall cavity (where the existing unit is). Now you can still access the sharkbites down below. That way, you still have the (corrected) configuration, but you CAN still access it if it gives problems in the future simply by disconnecting the two sharkbites and lowering the entire assembly back out of the wall cavity (sharkbite removal tool costs only a buck or two). Just a thought.

[powercat_ras]

Note that the BFP *does* serve a purpose besides preventing back flow into your garden hose and possibly drinking water supply connected to the black flush connection. As noted by a prior poster it prevents any black tank fumes from getting out to the connection in the wet bay and causing odors.

So - - - consider cutting the 2 blue PEX and pulling down the BFP you already have in your RV. Chances are it is good and was just installed in reverse direction. As was noted by prior poster if installed in reverse it would do exactly as you originally described, spraying water out the BFP air vent holes and preventing water from getting to the black tank flush spray head. You can test it and if it is good re-use, otherwise you can buy another one at a home center. You can use two compression fittings or shark bites to reinstall it. As was noted two feet above the top of the black tank is RVIA code but less than that would be OK, I would say at 12" above top of black tank would do fine.

[powercat_ras]

FYI, this is what Winnebago used in the 2015 Vistas. Note the two different kinds of PEX they used on the hose connection and flush sprayer sides of the Backflow prevention device that made it easy for their factory workers to get it installed the right way. It looks like they also used a check valve in series with the BFD (the white piece).

[mrf1002u]

Originally Posted by 4x4van

How about making up a new BFP assembly, with 2 short (maybe 18-24") lines. Then, using sharkbite connections where you plan to install bypass, instead install the new "assembly" sticking up into the wall cavity (where the existing unit is). Now you can still access the sharkbites down below. That way, you still have the (corrected) configuration, but you CAN still access it if it gives problems in the future simply by disconnecting the two sharkbites and lowering the entire assembly back out of the wall cavity (sharkbite removal tool costs only a buck or two). Just a thought.

Before I even saw this post I had already bought the little crecent shaped tool, in case I needed to undo any pipes, but I think I have been talked out of putting a BFP back in. The ONE thing I wanted not to ever happen to my RV (water inside) happened on the first trip. And even if the BFP is in backwards, I got enough tales of leaking BFP's to scare me off from another one.

Having a better understanding now, I believe if I put the bypass up to the level of the countertop (24"-36" above tank), and put a shutoff valve in the line near the tank wash connection to prevent siphoning and or off gassing, it should be fine. As mentioned previously, if the screw in BFP will hold air as well as water, I may even skip the valve. Instead, after washing the tank, unscrew the BFP and let the water drain from the lines as it does now. The tank is now empty because I had just washed and dumped it, so no water siphoning possible. Then just screw the BFP back in. IF there is no water in the lines to the high point of the added bypass, I don't see a way for it to siphon water. I would think even just screwing a male hose plug into the San T Flush connection after draining the flush lines would be sufficient for the off gassing.

Thanks for the suggestions!

Larry W.

[mrf1002u]

Originally Posted by powercat_ras

FYI, this is what Winnebago used in the 2015 Vistas. Note the two different kinds of PEX they used on the hose connection and flush sprayer sides of the Backflow prevention device that made it easy for their factory workers to get it installed the right way. It looks like they also used a check valve in series with the BFD (the white piece).

Thanks. Looks like Winnebago had their head screwed on tighter than Thor did. IF i did put another one back in, I would for sure go with something higher quality like the brass one you posted. The check valve seems redundant, but welcome.

Part of the reason I am put off from the BFP is the location. Under the sink seemed a better choice than hidden in the shower wall, but at this point I would rather eliminate it than relocate it.

Seems to me now, that the bypass up high, along with drained lines and a shutoff valve down below in the wet bay will solve any issues with water or gasses.

Thanks.

Larry W.

[4x4van]

Well, hope the install/bypass goes well for you. If it were me, I would reinstall the corrected version, but to each his own. Just seems like installing a bypass, and a shut-off valve, and using an anti-syphon on the hose...Too many extra things/steps to remember and to possibly go wrong when correcting the issue (and making any possible future failure easy to repair) is simple and easy. You say you've seen "enough tales of leaking BFDs" to scare you, but the reality is that no one goes online and posts "Hey guys, my BFD's working great... How about yours?" FWIW, in 28 years I've never had one fail, so...YMMV.

[j.smith]

Ever get those black tank odors in the coach and can't figure out where they are coming from.... If you look at the cutaway of the back flow preventer and imagine it connected to the black tank you will have found your source for the odors. When the valve is operating properly and there is no water flow thru the valve, the disk drops down and opens the path from the tank thru the valve and into the interior of your coach.

My vote is remove the bfp, install one at the hose connection with a shutoff valve, your nose will appreciate the mod and as long as the hose end connector is installed you will satisfy any back flow requirement.

Just my $0.02

[powercat_ras]

Proballly why Winnebago has the check valve on the black tank side of the BFP. No odors possible.

[j.smith]

Originally Posted by powercat_ras

Proballly why Winnebago has the check valve on the black tank side of the BFP. No odors possible.

I don't understand the check valve as it defeats the purpose of the back flow preventer, with the check valve the bfp is not really functional so it might as well not be there...

[dabrooks]

Here are two pictures of the way I have mine set up. The hose that I use to flush the black tank has a quick connect on it also. When I unhook either hose I let it drain to the ground and then fold it up into the wet bay for storage.

I close the shut off on the gray hose when I am done so odors from the black tank don't get in the wet bay.

My air gap/check valve was under the bathroom sink. I took it out and got a double male 90 and used that to connect the two pieces of PEX together. It has been set up this way for three years with no problem.