Black tank flush mod on 2018 28BHBE

[ibra0078]

I been reading stories where the black tank flush will eventually leak over time. I want to prevent it from happening and wondering if anybody has instructions of how they did the mod. If I'm not mistaken the flush valve is split and that value that Jayco uses is pretty cheap. So instead they run it straight into the black tank. Just trying to get more information of how it was done.
Thanks

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[Bassdogs]

Originally Posted by ibra0078

I been reading stories where the black tank flush will eventually leak over time. I want to prevent it from happening and wondering if anybody has instructions of how they did the mod. If I'm not mistaken the flush valve is split and that value that Jayco uses is pretty cheap. So instead they run it straight into the black tank. Just trying to get more information of how it was done.
Thanks

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First understand that there is some controversy to the mod. I simply removed the flush valve [vent] and reconnected the plumbing so that the flush shoots directly into the tank. The valve is there Ive been told to provide a vacuum break and to prevent potentially syphoning back out of the flush fill connection.

My flush valve was defective and diverted incoming water back out the vent resulting in flooding inside the TT. It is not supposed to do that as a ball is designed to block the vent and open the flow into the tank but the failure I experienced is apparently fairly common. Its an easy mod, just a little awkward working under the bathroom sink cabinet.

After the mod, you connect the water line to the flush input on the side of the trailer and turn on the water. When done, shut off the water and dump.
Syphoning will not occur if the flush connection is higher than the top of the black tank. You can also protect things by turning off the water and then slowly loosening the connection of the line to "vent" pressure from the line before completely removing the hose.

[ibra0078]

Interesting, the leaks occurs because the valve that suspose to prevent backflow fails? Is that same line joined with another line?

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[ibra0078]

Has anybody used the flush king valve vs using the black flush valve on the side of the TT

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[troutslayer]

Originally Posted by ibra0078

Has anybody used the flush king valve vs using the black flush valve on the side of the TT

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A friend of mine uses one of those and all it did was clean part of the pipe. Didn't do anything for rinsing the tank. Probably depends on if the tank is at the same level as the rinser. But even then I don't see it rinsing anywhere as good as the flush.
I also know folks who have removed the rv back flow preventer and then used a vacuum break on their rinse hose...does the same thing.

[Bigmoo315]

I use the flush King valve and it works pretty good. I just attach the hose,time it out for about five minutes and then open the valve. Sometimes I’ll do if you times until it comes out clear. It definitely comes out more than just line it back so if into the tag and will fill the tank until it comes out inside the camper so you have to be careful.[emoji51]

[ibra0078]

Good to know, I have a black flush valve on mine but if this does a better job then may be worth it.

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[travelingjw]

I use the Flush King valve at every stop. I install it when I hook up my sewer hose. I find it works for me but also will note that there is a "YouTube" video that test all of the different methods of cleaning the tanks. It showed that all it did was to fill the tank, the higher you filled it, the more debris that would empty.

[vcbice]

The Flush King does not do even half the job the tank flush does. The built in tank flush sprays most of the inside of the black tank, not just pushing water back in through the valve. And, since there is a 90 deg turn into the tank (at least on my trailer), the full force of the spray is not getting to the tank.

But, the built in tank flush unit can get plugged up and not work until you take it out and clean it. Not a job for the feint of heart

The backflow preventer on the flush line is provided per code. It prevents black water from flowing out that line if the tank is over filled. The valve is up above the top of the toilet for that reason (as well as not allowing a suction back to the water supply line). Due to a leak I disconnected the lines to that valve on my unit.

About once a month I use a good wand in through the toilet to clean out the tank as much as possible. It is also handy if there is a partial blockage at the tank outlet.

[oobedoob]

YouTube channel "The fit RV" has a bunch of videos where he mocks up a black tank in a clear box and tests a few of the add on flushers. Very interesting to watch

[JohnWedell]

I have often thought about putting a second black tank flush on the other side of the tank. With my luck the black tank flush is on the same side as the sensors and they don’t get cleaned.

[ibra0078]

Originally Posted by vcbice

The Flush King does not do even half the job the tank flush does. The built in tank flush sprays most of the inside of the black tank, not just pushing water back in through the valve. And, since there is a 90 deg turn into the tank (at least on my trailer), the full force of the spray is not getting to the tank.

But, the built in tank flush unit can get plugged up and not work until you take it out and clean it. Not a job for the feint of heart

The backflow preventer on the flush line is provided per code. It prevents black water from flowing out that line if the tank is over filled. The valve is up above the top of the toilet for that reason (as well as not allowing a suction back to the water supply line). Due to a leak I disconnected the lines to that valve on my unit.

About once a month I use a good wand in through the toilet to clean out the tank as much as possible. It is also handy if there is a partial blockage at the tank outlet.

The leak then occurs because of the cheap backflow preventer they use? You disconnected the lines , does that mean you are not using the flush line anymore. What if one removes the backflow preventer so they have a straight shot into the tank.

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[Bassdogs]

Originally Posted by ibra0078

The leak then occurs because of the cheap backflow preventer they use? You disconnected the lines , does that mean you are not using the flush line anymore. What if one removes the backflow preventer so they have a straight shot into the tank.

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Key word in previous post is "code". Most know I'm not a big code person but that is another story. If you have ever had a lawn sprinkler system, you had to have a backflow preventer as required by code so that contaminated water can not syphon back into the city water system. The RV thing stems from the same concept. Difference is in most cases the flush connector on the side of the TT is higher than the top of the toilet so if the black tank was over filled, that is where the overflow would take place. Problem is that the cheap a*s valve that the RV industry uses is known for failures. A replacement would have a high likelihood to fail as well. since the result of the problem in my case was a flooded TT, I choose to eliminate the valve all together and connect the flush directly to the black tank. If you flush at a dump station, the water connection is non potable and you aren't at risk of contaminating the fresh water system. Remember to disconnect the fill hose immediately after finishing the flush and all will be good.

[JohnWedell]

Could’t You just put a check valve on the black tank flush inlet and leave it there.

[Bassdogs]

Originally Posted by JohnWedell

Could’t You just put a check valve on the black tank flush inlet and leave it there.

Probably but its just something else that could break or leak.

[o2silverado]

So what I gather from this is the water actually enters the tank through the vent stack ? It is not a sprayer that is located in the tank itself? I have installed several of the the no fuss-flush units in past units without a single issue ever.

[ibra0078]

I think the line is connected to a sprayer but I may be wrong.

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[Atlee]

My black flush line failed the very last time I used it before shutting down the RV until this coming spring. I don't know what piece actually failed. I notice a lot of water in the storage compartment when I was putting stuff away. I'll figure that out when the 23RB comes out of hibernation this spring.

Fortunately, on my 23RB, the black flush connection is high on the rear end, and goes through into the large storage compartment, then goes down to the floor, then across the floor and then disappears through the floor and into the black tank.

I will have to empty the storage compartment [blocks, ramps, stinky slinky and other dump supplies and equipment]. I installed a divider to shield the water line from the stuff I store in the compartment.

Originally Posted by Bassdogs

Key word in previous post is "code". Most know I'm not a big code person but that is another story. If you have ever had a lawn sprinkler system, you had to have a backflow preventer as required by code so that contaminated water can not syphon back into the city water system. The RV thing stems from the same concept. Difference is in most cases the flush connector on the side of the TT is higher than the top of the toilet so if the black tank was over filled, that is where the overflow would take place. Problem is that the cheap a*s valve that the RV industry uses is known for failures. A replacement would have a high likelihood to fail as well. since the result of the problem in my case was a flooded TT, I choose to eliminate the valve all together and connect the flush directly to the black tank. If you flush at a dump station, the water connection is non potable and you aren't at risk of contaminating the fresh water system. Remember to disconnect the fill hose immediately after finishing the flush and all will be good.

[Bassdogs]

Originally Posted by Atlee

My black flush line failed the very last time I used it before shutting down the RV until this coming spring. I don't know what piece actually failed. I notice a lot of water in the storage compartment when I was putting stuff away. I'll figure that out when the 23RB comes out of hibernation this spring.

Fortunately, on my 23RB, the black flush connection is high on the rear end, and goes through into the large storage compartment, then goes down to the floor, then across the floor and then disappears through the floor and into the black tank.

I will have to empty the storage compartment [blocks, ramps, stinky slinky and other dump supplies and equipment]. I installed a divider to shield the water line from the stuff I store in the compartment.

Since the overflow sat inside the storage area over the winter it had plenty of time to find its way under the linoleum floor cover. You might want to cut out that linoleum and allow the subfloor to dry out. I had this problem on a older keystone TT and found that the subfloor was wet several feed from the actual leak. I cut out all the oem linoleum and after drying the subfloor, treated the whole floor with Thomsons water seal. I then put in a new plank floor. In your case I would cut out the material in the storage area. After drying and sealing the subfloor you might elect to cut a piece of carpet to fit. That way it is easy to pull out the carpet when necessary and clean up the storage area before reinstalling the carpet piece.

[nighthawk87]

Thanks for this thread. It has convinced me to NOT install a black tank flush. Instead the best way is still the wand from the top.

Sewage leaking in my trailer. Disgusting. I’d have to get rid of it.


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