Black Water Flush

[dhind]

Perhaps a silly question, but why does the manual require the black water tank valves be open when doing a black water flush. Surely the tank is vented. Is the concern backing up the system through the toilet? I much rather fill it and let it flush out, than just run water through the bottom of the tank.

Not new to motorhomes, but new to our 2015 Georgetown 270.

Dave

[Sbryant]

If you don't open that valve, the back flush water will come out in the bathroom where the vent is.


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[SKnight]

That's it, the concern is that you don't actually know how full it is. I could fill up, fill the toilet, then even go out the roof vent. Plus, once it's got water in it, the flush isn't flushing anymore, it's just filling with water.

When I dump it if there's not a line I'll flush it with the valve open, once it's running reasonably clear I'll close the black valve, let it flush for several minutes, then will open the valve again. That lets it build up some water, then will purge what's in the corners out.

[Trempert]

Originally Posted by dhind

Perhaps a silly question, but why does the manual require the black water tank valves be open when doing a black water flush. Surely the tank is vented. Is the concern backing up the system through the toilet? I much rather fill it and let it flush out, than just run water through the bottom of the tank.

Not new to motorhomes, but new to our 2015 Georgetown 270.

Dave

Because you could contaminate the city water supply if the water level got up to the jet spray nozzles. Other reasons too, but this is the primary reason.


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[bubbles]

Originally Posted by dhind

Perhaps a silly question, but why does the manual require the black water tank valves be open when doing a black water flush. Surely the tank is vented. Is the concern backing up the system through the toilet? I much rather fill it and let it flush out, than just run water through the bottom of the tank.

Not new to motorhomes, but new to our 2015 Georgetown 270.

Dave

You have the right idea for black tank cleanout if it was installed correctly. Just don't start the cleanout and wander off. It takes about 20 minutes for my tank to fill up from the cleanout. I use the indicator and also look directly down the toilet to the tank to know when it is full. You will never have an indicator issue from build up with this procedure. I do use an enzyme additive between dumps. There are a lot of urban legend tales out there concerning the black tank cleanout. The vent is out the roof not in the bathroom. There is no way contaminated water can get in the fresh water system. These are just my input to some of the previous inputs.

[dhind]

Thanks. That exactly what I expected. Just wanted to make sure I didn't miss anything. 20 years of RVi g, but still new information.

[Greg_Travels]

I made the mistake of starting my black tank flush with the valve closed and got distracted. The next thing you know I've got water coming out of the toilet onto the floor. After drying up the mess and emptying the tank, subsequently black tank flashings result in water coming out of a pipe under the water heater area. The pipe has a rubber hose slide over it with the end molded in a pinched, but open, position. What could be causing the black tank flush to run out of this pipe even when the black tank valve is open?

[VinceU]

Originally Posted by Greg_Travels

I made the mistake of starting my black tank flush with the valve closed and got distracted. The next thing you know I've got water coming out of the toilet onto the floor. After drying up the mess and emptying the tank, subsequently black tank flashings result in water coming out of a pipe under the water heater area. The pipe has a rubber hose slide over it with the end molded in a pinched, but open, position. What could be causing the black tank flush to run out of this pipe even when the black tank valve is open?

There is a non-return/vacuum breaker device mounted about 3-4 feet above the tank. Fresh water is routed into the RV, up to the vac break down to the tank flush and sprayed into the tank. Purpose is if shore pressure is lost and the system develops a vacuum, the breaker will prevent the contents of the black tank from being syphoned back into the city water system.
Your problem sounds like a defective vac breaker. Found in closets, in hollow walls. In your case above the dripping compartment. Home repair centers sell them.

[Coach 350]

I agree with Bubbles. I empty it first then empty the grey water tank. At campsites I fill it 1/3 then flush again and again. Never an odor and my sensors are kept clean too.



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[Islander]

Greg_Travels ... your post gave me chills down my spine !!!!

I love my Black Water Flush and am thinking of adding some to my 2 gray holding tanks as well.

When I dump I will always top up the black tank with water with the Flush- Sprayer.... fortunately I can hear the spraying water (inside the tank) form outside the RV and when I stop hearing it spray I Open The Dump Valve.
If I am leaving the CG I will fill/rinse the black tank at least once more with the Black Flush Sprayer...and again as soon as I do not hear the 'spray" I pull the dump lever.
This may take some time BUT I NEVER Leave while doing this process....for the very reason you mentioned in your post.

Side note: if you can not hear the spraying water from outside your RV try using a 2ft piece of 1/2" wooden dowel...round off one end and place the round end to your ear (at the position between your temple and outside your ear) and the other end near the vicinity of the back tank or buy a cheap stethoscope .

hope this helps

Islander

[Greg_Travels]

I can hear the black tank flush spraying inside the black tank but I'm getting water elsewhere that is coming out of a lower line on the other side of the RV. I'm just wondering if the sprayer got pushed partially out of the black tank and is spraying both inside and outside the tank into a different area. I wish there was some kind of plumbing schematic on the Georgetown 378 XL.

[Coach 350]

Originally Posted by Greg_Travels

I can hear the black tank flush spraying inside the black tank but I'm getting water elsewhere that is coming out of a lower line on the other side of the RV. I'm just wondering if the sprayer got pushed partially out of the black tank and is spraying both inside and outside the tank into a different area. I wish there was some kind of plumbing schematic on the Georgetown 378 XL.

Are you sure the low drain plug is in tight on the other side?


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[bubbles]

Originally Posted by 3C and S

Are you sure the low drain plug is in tight on the other side?


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This is a moot question. The black tank clean out is a self contained system and does not tie in with any fresh water plumbing system. Think about what you are asking.

[GABoy]

My 2014 351 has a leak at the inlet of the black tank on the black tank sprayer nozzle. So fresh water will dribble into the compartment below when using flush line. It fried our inverter on 800 mile trip home from dealer. Had inverter fixed then. Dealer tried a repair but didn't hold. Dealer now has new black tank and new flush lines to be installed in August. Nasty job ahead. Glad I'm not doing it!😬


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[The Wandering Irishman]

On my 2014 351DS the black tank flush suddenly quit working. Before I'd hook up the hose and it'd flush out nice! Now I hook up the hose and it acts as if it's already pressurized and no water goes in, when I unhook the hose water drips out of the inlet from the pressure. I have to assume I have a blocked outlet but don't have a clue where to even begin! Ugh! I miss having it though!

Tom



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[Coach 350]

Originally Posted by bubbles

This is a moot question. The black tank clean out is a self contained system and does not tie in with any fresh water plumbing system. Think about what you are asking.

Know that it is separate from the black tank. Sometimes the little things are missed when checking. Trying to eliminate why water is coming out other side of motorhome.


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[VinceU]

Originally Posted by Greg_Travels

I can hear the black tank flush spraying inside the black tank but I'm getting water elsewhere that is coming out of a lower line on the other side of the RV. I'm just wondering if the sprayer got pushed partially out of the black tank and is spraying both inside and outside the tank into a different area. I wish there was some kind of plumbing schematic on the Georgetown 378 XL.

The piping is led from the inlet, thru the basement to the water heater. From there up 4' and enters the vac-breaker. All the 378's I've seen this is the laundry locker.Routs back down to the basement and into the black tank nozzle. The fresh water system at this point is common with the black tank vapor. It the job of the vac brk to prevent back flow it's required by Fed code to be there.


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[Coach 350]

Hey Vince, I see you are from Delran. Next door to you in Palmyra b



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[Coach 350]

Try this website. www.rv-insight.com>rv-plumbing. Basic schematic. No vacuum breaker showing, but I am sure there is one in the system.


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[Coach 350]

Winnebago has a plumbing schematic for their motorhomes. I punched in their journey 36 motorhome and it shows full schematic showing everything. Roof vent, vacuum breaker , etc. Here is the website.

Winnebagoind.com>resources>manuals.



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