Grey Tank Draining Slowly

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Joined
Nov 17, 2019
Messages
991
Location
Prince William, VA
RV Year
2020
RV Make
Newmar
RV Model
Ventana 4326
RV Length
43
TOW/TOAD
2020 Ford F-150
Noticed a few days ago that our grey tank has started draining much slower. Not sure what happened and I haven’t made any plumbing changes yet (wet bay project). Usually when I pull the gate, there’s a huge blast of grey water and the clear elbow is just completely full, draining as fast as it possibly can but in the last few days, I’ve noticed that that’s not happening anymore and I only see about 1/2 the volume draining and it takes much longer to dump. Black is completely fine and operating as expected.

Obviously it sounds like a blockage but we don’t put any kitchen scraps or grease down the drain so I don’t know where a blockage would have come from.

Unfortunately in all their wisdom, Newmar decided not to put in a tank rinse valve in the grey tank on the Ventana. I'd been expecting to install one myself as part of my yet, mostly unstarted wetbay project and requested a 4326 tank diagram from Newmar so I could plan that part of the project out. I was kind of dumbfounded by what I got back.
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413603 20171020 (28).jpg


It wouldn't have occurred to me in 1,000 years that the Grey and Black tanks would be designed into sections that are split by the frame rails like that. What a poor design decision! There could be a good reason for it but this simply does not compute in my feeble mind.

Now, I've designed zero recreational vehicles so I feel very well qualified in saying this, but in looking at the tank design the only proper way to install a grey tank rinse is to have 3 rinse valves run in series, one for each tank section. That's doable for the tank sections on each end but there's not really a good way to access the center tank section. I'm slim but not that slim.

The even more confusing thing is that Newmar easily could have put the fresh water tank between the rails instead. A fresh water tank should never have any kind of debris in it so splitting it into sections across the chassis rails like that would be a nonissue. Debris is to be expected in black and to lesser extent in grey as well. So why create choke points like that? They could have also installed a drain in each tank section and run those in series all the way to the gate to avoid this issue, but didn't do that either. The whole thing makes no sense to me.

Anyway, back to the issue at hand. Anyone have any thoughts on my slow draining grey tank and how I might get it back to normal without creating a disgusting mess?
 
Joined
Jul 27, 2019
Messages
3,916
Location
Midlothian, VA
RV Year
2017
RV Make
Newmar
RV Model
Ventana 4037
RV Length
40' 10"
TOW/TOAD
2017 Chevy Colorado
Fulltimer
No
While I've been using sani-con for a while now I think it may just be a vent situation, i.e. in order for the water to come out at a good rate there has to be a top side vent allowing it to release without some type of suction event. In my opinion I would say don't worry about this, I think you're over analyzing the draining of the gray and it's probably fine and nothing is blocked. The drain hole is 3 inch, I'm not sure if on yours there is a 1.5 inch step down on the piping or if they smartened up and kept it 3 inch the entire path now. If you're concerned about any build up I recommend cascade, if that can break down food in a dishwasher it has to be something good for what we put in the gray tank.

Has this occurred since you arrived at a new location? I wonder if how level your coach is, or not, has anything playing in here. Again, I think this is just a situation with venting and nothing to worry about.
 
Joined
Nov 3, 2019
Messages
187
Location
West Palm Beach Fl
RV Year
2017
RV Make
Newmar
RV Model
Ventana 4369
RV Length
44
TOW/TOAD
Buick Enclave
Vent blockage?
 
Joined
Jul 27, 2019
Messages
3,916
Location
Midlothian, VA
RV Year
2017
RV Make
Newmar
RV Model
Ventana 4037
RV Length
40' 10"
TOW/TOAD
2017 Chevy Colorado
Fulltimer
No
Joined
Nov 3, 2019
Messages
461
Location
TGO Titusville FL
RV Year
2015
RV Make
Newmar
RV Model
Dutchstar 4369
RV Length
43
TOW/TOAD
2014 Honda CRV
Noticed a few days ago that our grey tank has started draining much slower. Not sure what happened and I haven’t made any plumbing changes yet (wet bay project). Usually when I pull the gate, there’s a huge blast of grey water and the clear elbow is just completely full, draining as fast as it possibly can but in the last few days, I’ve noticed that that’s not happening anymore and I only see about 1/2 the volume draining and it takes much longer to dump. Black is completely fine and operating as expected.

Obviously it sounds like a blockage but we don’t put any kitchen scraps or grease down the drain so I don’t know where a blockage would have come from.

Unfortunately in all their wisdom, Newmar decided not to put in a tank rinse valve in the grey tank on the Ventana. I'd been expecting to install one myself as part of my yet, mostly unstarted wetbay project and requested a 4326 tank diagram from Newmar so I could plan that part of the project out. I was kind of dumbfounded by what I got back.
View attachment 1714
View attachment 1715
View attachment 1716

It wouldn't have occurred to me in 1,000 years that the Grey and Black tanks would be designed into sections that are split by the frame rails like that. What a poor design decision! There could be a good reason for it but this simply does not compute in my feeble mind.

Now, I've designed zero recreational vehicles so I feel very well qualified in saying this, but in looking at the tank design the only proper way to install a grey tank rinse is to have 3 rinse valves run in series, one for each tank section. That's doable for the tank sections on each end but there's not really a good way to access the center tank section. I'm slim but not that slim.

The even more confusing thing is that Newmar easily could have put the fresh water tank between the rails instead. A fresh water tank should never have any kind of debris in it so splitting it into sections across the chassis rails like that would be a nonissue. Debris is to be expected in black and to lesser extent in grey as well. So why create choke points like that? They could have also installed a drain in each tank section and run those in series all the way to the gate to avoid this issue, but didn't do that either. The whole thing makes no sense to me.

Anyway, back to the issue at hand. Anyone have any thoughts on my slow draining grey tank and how I might get it back to normal without creating a disgusting mess?
I can’t imagine how the tanks could be replaced if need be? I also develop a slow draining of the gray tank. Thought it may be a mud dobbers Blocking the roof vent, but did not find any blockage. Waiting to see what you may find?
 
Joined
Jul 27, 2019
Messages
3,916
Location
Midlothian, VA
RV Year
2017
RV Make
Newmar
RV Model
Ventana 4037
RV Length
40' 10"
TOW/TOAD
2017 Chevy Colorado
Fulltimer
No
They can be removed quite easily, they are on a shelf that's dropped I presume is how. Fresh has to come out then black and gray come down.
 
Joined
Nov 17, 2019
Messages
991
Location
Prince William, VA
RV Year
2020
RV Make
Newmar
RV Model
Ventana 4326
RV Length
43
TOW/TOAD
2020 Ford F-150
Vent blockage is a good thought that hadn't occurred to me. I will check into that. We have been sitting for a while and will be moving in two weeks. I don't plan to do anything until I've driven her down the road with a half full tank let things slosh around. For anyone that might need it, here's the drain and water line schematics as well
4326 - Drain.png

4326 - Water Lines.png
 
Joined
Nov 17, 2019
Messages
991
Location
Prince William, VA
RV Year
2020
RV Make
Newmar
RV Model
Ventana 4326
RV Length
43
TOW/TOAD
2020 Ford F-150
I can’t imagine how the tanks could be replaced if need be?
It wouldn't be fun. Completely disassemble the wetbay, then the freshwater tank and pull it, then drop the gray/black tank(s) and replace as needed - no small project.
 
Joined
Jul 27, 2019
Messages
3,916
Location
Midlothian, VA
RV Year
2017
RV Make
Newmar
RV Model
Ventana 4037
RV Length
40' 10"
TOW/TOAD
2017 Chevy Colorado
Fulltimer
No
Hopefully you never need to but in my wet bay work I knew the risks in what I was doing may require it, I was fortunate that was not the case. I had to take a gamble in changing the piping from 1.5 inch to 3 inch that the fitting was not glued in, that turned out to be correct. Newmar can and does do it, once you do it I think it's just labor intensive in the disassembly, I can't image the vent removals etc. That is nothing cheap.

Anyhoo, great schematics. Looks like there is a line aft of the gray that goes to the roof. May just want to pop up there and make sure no winged critters have nested in a vent but doubtful. They get fragile after being in the sun, I know as I tapped one to put it back in alignment and it shattered so I got to learn to replace it. Again, something that was better when done, the replacement vent was far better than what Newmar installed.

Try some dish detergent and/or cascade and/or pine sol in tanks, drive to next location then dump, fill/rinse, dump and enjoy more camping.
 
Joined
Dec 4, 2019
Messages
10
Location
Pleasanton, CA
RV Year
2019
RV Make
Newmar
RV Model
Dutch Start 4018
RV Length
40
TOW/TOAD
1973 Toyota FJ40 / Jeep GC Limited
MapNerd:
I think the guys have the problem located with your vent. Have had it happen to me too.
I'm looking at adding a rinse to my grey tank as well. Added to to my two previous DPs and have been very happy with the mod. While it may not rinse all of the tank because of the strange shape of the Newmar tank, it will do some rinsing and will be an easy way to add water to the tank before I dump. I'll add a flow meter to the hose so I can monitor how much water is going into the tank and don't overfill.
I'm looking at coming in from the PS at the pegboard bay for the tank rinse as the black and grey tanks are right there, then run the hose over the tanks to the wet bay where I'll connect with a "Y" with shutoffs at the black tank rinse. That allows me to rinse the black and grey at the same time or use the "Y" to add water to one or the other tank only. First thought for the rinse was to put on the top of the tank by removing the plastic shroud above the pegboard, but that doesn't look like it will work. I need to remove the pegboard and see what kind of access I can get on the side, front, back of the tank. This will be a project for another weekend.
Good luck with your project.
Mike
 
Joined
Nov 4, 2019
Messages
762
Location
No Where In Particular
RV Year
2020
RV Make
Newmar
RV Model
Dutch Star 4369
RV Length
43’ 9”
TOW/TOAD
2016 Colorado
Fulltimer
Yes
Just a heads up on slow draining of tank a friend had on his Ventana, he found construction debris in has that finally worked it was into the drain pipe. Once removing the piece of plastic piping all was good. This was on a 2017 VT, didn’t show up for 2 years. Something to look at if vent is not the issue.
 
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