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Topic: Waste Valve set up (Read 1820 times) previous topic - next topic

Waste Valve set up

I think I have an idea now after reading through old posts how this works.  I like the idea of flushing gray water through the black water tank to help flush it out.

But it seems that if the third valve is closed after emptying the black water tank and with the black water tank valve is still open and the gray water tank valve is opened, gray water will back up into the black water tank until some equilibrium is reached or a disater occurs. 

Then what?  Close the gray water tank valve and open the third valve and drain the black water tank, then close the black water tank valve and open the gray water tank valve and drain the rest of the gray water.

The possibility of getting black water stuff backed into the gray water tank bothers me.  It seems like they should be kept separate.

Is there a check valve in the gray water waste line ahead of the gray water valve to prevent backflow?

Since the gray water tank is almost twice the size of the black water tank isn't there a chance of a black water tank overfill (overflow).  Ugh!

It seems like it would be nice to have the option of emptying the gray water tank directly or routing it through the black water tank in series (after it has been emptied) to flush it out.

So from those who have done this mod to one who is thinking about it, how does it work? Any problems? Did you domit differently than I am imagining?

Maybe a diagram would be helpful.  Never found one of those.

Thanks

Roger

Re: Waste Valve set up

Reply #1 –
Roger,

With black tank open and drained, close third valve, open gray tank that has lots of water in it for a count of two and then close grey tank.

Open third valve and allow the disturbed afluent in the black tank to drain. Repeat till clean.

Close black tank and open grey to allow it to finish draining.  No chance of afluent backing up into grey tank with this procedure.

Hope this helps.

Re: Waste Valve set up

Reply #2 –
Quote from: Home2fromHastings –
I think I have an idea now after reading through old posts how this works.  I like the idea of flushing gray water through the black water tank to help flush it out.

But it seems that if the third valve is closed after emptying the black water tank and with the black water tank valve is still open and the gray water tank valve is opened, gray water will back up into the black water tank until some equilibrium is reached or a disater occurs. 

Then what?  Close the gray water tank valve and open the third valve and drain the black water tank, then close the black water tank valve and open the gray water tank valve and drain the rest of the gray water.

The possibility of getting black water stuff backed into the gray water tank bothers me.  It seems like they should be kept separate.

Is there a check valve in the gray water waste line ahead of the gray water valve to prevent backflow?

Since the gray water tank is almost twice the size of the black water tank isn't there a chance of a black water tank overfill (overflow).  Ugh!

It seems like it would be nice to have the option of emptying the gray water tank directly or routing it through the black water tank in series (after it has been emptied) to flush it out.

So from those who have done this mod to one who is thinking about it, how does it work? Any problems? Did you domit differently than I am imagining?

Maybe a diagram would be helpful.  Never found one of those.

Thanks

Roger
That is the procedure I use to empty the tanks.
There is no check valve.

The tanks will equalize to the same level and should not overflow.
You don't need to wait until they equalize to shut the grey valve. It only needs that initial rush.

Look at the photo of my configuration to see it would be difficult to back up into the grey, which really is not an issue if it does.
It is all emptying into the same place.
I have never seen any solids come out of my grey tank.

When you close the black tank valve you are emptying the grey water directly.

I think it does help to open the grey into the black to dislodge any thing still in there as I always see additional solids coming out while doing it after I thought it was clean.

Re: Waste Valve set up

Reply #3 –
When you back flush the black tank with the grey water, there is a mixing of the two tanks water. Most if not all of the solids should have emptied with black, I have no issues with mix. Even if you choose not to back flush, 3rd valve nice back up to primary valves

Re: Waste Valve set up

Reply #4 –
I hook up the drain hose and make sure everything is secure and ready, then

open third valve
open black valve, allow full drainage, close third valve
open grey valve, allow full equalization between grey and black tanks, close grey valve
open third valve, allow full drainage, close third valve

repeat a couple of times

after third time dumping black, leave third and black open, the open grey to empty everything

Effluent is usually pretty much soapy grey water after first back flush is drained.

I also put Dawn and some fresh water down the toilet after dumping to provide moisture and surfactant to the black tank. We have overflow traps built into the toilet bowl, and I make sure they are filled with fresh water after I empty the holding tanks.

Re: Waste Valve set up

Reply #5 –
I have always found it interesting that folks worry about getting black water in to the gray water tank or drain. They are together in a sticks and bricks house and it's no problem. The gray water drains have traps in them that would keep any odor out. Just interesting. ^.^d

Re: Waste Valve set up

Reply #6 –
Amount of coaches out there including FT Combined black and gray water tank

Re: Waste Valve set up

Reply #7 –
I totally agree with Larry, to many hours spent on unimportant things like this. I have 3rd valve and do not worrty if grey goes into black (or vice versa) and as Barry said "it all goes the same way anyway"
Do the change Roger and then worry about something important- like is it happy hour yet!
JohnH

Re: Waste Valve set up

Reply #8 –
Holding tanks are just that - holding tanks.  If they are RV waste tanks, it doesn't much matter what is in them as long as they are dumped in the proper dump hole when you dump.  Some SOB Class C units dump the shower drain into the black tank.  That isn't much fun if you are taking a shower and the tank is almost full and you think it will fit!!!

Re: Waste Valve set up

Reply #9 –
Thanks, folks. 

I am just a really curious sort and want to understand how stuff works. In any case I would prefer to minimize black into gray contamination.  I like Rudy's procedure.

My 2001 has 110 gal gray and 54 gal black tank capacity.  So if black is empty and gray is getting close to full, equalizing levels shouldn't overfill the black tank.

Thanks for helping me think this through. Another thing on my list (growing) of coach projects. Best to know where I am going and why, at least for me.

Yes, in your home the waste system shares common pipes but you don't have holding tanks in your house. Sinks, showers and any gray water source drain are never in common with black water drains until the main stack.  Properly done, black water never goes into the gray water drain lines unles there is a nasty backup.  Even when gray water is saved for use in lawn and garden watering it is carefully isolated from black water with an entirely separate plumbing system.

Roger

Re: Waste Valve set up

Reply #10 –
On my old 93 GV 225 I had a pipe from the bottom of grey tank to top of Black tank and 2 valves and a bilge type pump. If grey was getting full I could send grey water to black tank without touching waste gates. Worked good and at same time helped keep the senders clean on sides.
JohnH

Re: Waste Valve set up

Reply #11 –
@Roger No need to freak out over black water contaminating the gray water tank. The new IH's only have one tank for gray and black. Seemed strange to me when I first heard it but after thinking about it what difference does it make. It all gets combined at the dump anyway. Boondockers have have been using the 3rd valve to combine tanks for years for extra capacity. The only way you are contaminating anything is if you allow the the tanks fill to the point that they back up into the shower. At that point you have made a huge mistake and need to find a dump right now! Even if that happens it's not a big deal. Dump and then clean the shower with Clorox. Not fun but not a tragedy either. :)

see ya
ken

Re: Waste Valve set up

Reply #12 –
With our pedal toilet, after we back flushed gray water into black tank, we smelled the gray water when flushing toilet. Seems that gray water smells worse than black water, and washing out the black tank with gray water left the gray smell in the black tank.

On our weekly dumping we feed a city water hose into motorhome and use it to clean toilet & drains, so we don't feel a need to back flush with the 3rd valve anymore.

Re: Waste Valve set up

Reply #13 –
Been back flushing since my 99 u270 accident in 02. No smells of any king with either the electric toilet or now the new manual one.  A full bowl of water goes down after back flushing if hooked to city water.

Re: Waste Valve set up

Reply #14 –
Lots of opinions on this one. We don't backwash at all. Instead, after dumping the black, We shut the valve and fill the toilet with a couple of gallons of water and give it a flush. That cleans out any remnants and I can see the clear water rushing through. Then close black and dump gray. Finish up with a the Dawn-Calgon treatment along with a bucket of water and we're good to go.

One time I waited behind someone at the dump a looong time. As it happened, it was another Foretravel, a 98. In talking with the dumper he explained to me that when he bought his rig (at Foretravel) they instructed him in the dumping procedure. That procedure entailed the initial black dump followed by two complete backwashes and finally, the gray.

Think I'll stick with the quick and easy.
jor

Re: Waste Valve set up

Reply #15 –
I solved this problem when I built and installed my own tank flush system. One side benefit is that the system cleans the back side of the tanks where the sensor tape is on the outside,the tank gauges read correctly.

Re: Waste Valve set up

Reply #16 –
Bill Willet, could you please post a schematic of your plumbing? I'm having some issues with getting accurate readings on my tank levels & I'm currently sitting in a boondock circumstance. Thanks

Re: Waste Valve set up

Reply #17 –
Fred, you have a different system than the later coaches. There are probes in the tank and the wires are screwed to the probes. On our 84 ored I installed the sea level system as the probes get toilet paper on them and gunk and then do not read right, but the sea level system is not affected that way. If you install the sea level you can use the wires that are already there and remove them from the plug on the panel in your dash. The hardest one is the fresh water tank and being able to place the strips on the tank

Re: Waste Valve set up

Reply #18 –
As I have posted previously. After draining the black water tank, I just raise the drain hose with the grey water valve open and open the black water valve. Then I close the grey and lower the hose until the black water empties and then replete that a coupe times. I often use dawn down the drains to Help loosen things up. I also tilt the coach to the side to completely drain the tanks.

Re: Waste Valve set up

Reply #19 –
Quote
I also tilt the coach to the side to completely drain the tanks.
When I removed my tanks I learned that they are installed on inclined platforms so it's already rolling downhill.
jor