Still in need of help PLEASE Gray Tank

[l1v3fr33ord1]

I see these things:

1) The three inlets go 1/3 into the tank. One-third of 36 gallons is 24 gallons, not far off the "20 gallons" mentioned.
2) The tank outlet and drain valve are higher than the bottom of the tank (by later post, may have been fixed by "hubby").
3) The left-most of the two inlets shown appears to be not perpendicular to the tank top plane, and shows signs of having a broken seal.
4) The tank is clean.
5) The sensors are on the outlet end of the tank.

What conclusions do I draw?

1) It's consistent that backup occurs in the tub drain near 2/3 "full," as the roof vent get covered with water.
2) It's consistent to get slow draining after the tank is almost empty, because the reverse pitch of the drain piping would prevent quick gravity draining.
3) The sensors are working fine.
4) If the left-most pictured inlet is the roof vent, and it is constrained from moving relative to the tank (among other things, I saw a screw through the pipe on the video), then the non-perpendicularity of the vent pipe is consistent with the tank having been driven upwards.
5) It is possible that leakage would occur around the broken seal and onto the top of the tank should the tank be filled to that point (unlikely considering the propensity to back up the tub drain).

I think the advice to check that the tank is not dislodged is wise. Other than that, I'm not sure what is really "wrong" here. I am surprised that the vent pipe terminates so far into the tank; that would guarantee a backflow in advance of the tank being full. However, if the tank was driven upwards a lot, then the vent pipe went deeper into the tank, decreasing the tank capacity before backflow.

[Lrakeahs]

Oh.. What I meant was.. Some were thinking that the gray tank was not emptying completely and that's where the extra 16 gallons was.....or so I was taking it that way.... Like they were thinking the tank was retaining water, I was trying to let them know that when I do empty the tank it drains completely. And when I took the photos of inside the gray tank it was completely empty...

[Lrakeahs]

The about above reply was in answer to cruzbill's last post.

[Lrakeahs]

The red arrow is the bathroom sink pipe... The 2 red circles are on the ceiling of the gray tank... Wondering what they are.... Hubby wondering if they are over flow valves...?

[CJ7365]

Originally Posted by Lrakeahs

The red arrow is the bathroom sink pipe... The 2 red circles are on the ceiling of the gray tank... Wondering what they are.... Hubby wondering if they are over flow valves...?

Just a guess, it looks like those are just extra pieces of plastic when the tank was made, leftovers from the mold. There is no consistency in shape to them, they are not smooth etc.....

I have never heard of an overflow valve on the gray tank.


If there was any kind of overflow on a gray tank, why would there be 2 of them, only tank with an overflow is fresh water holding tank.

[cruzbill]

Thanks for the clarification, it ain't the emptyin', its the fillin'! You might loose that 16 gal just due to the tank having enough slope. Check to see that the tank is sitting squarely in its frame.

[coachmanjay]

It appears that the problem is not with the tank not draining but that the water level when the tank is 2/3 full is above the elevation of the tub/shower drain.

[Lrakeahs]

Originally Posted by l1v3fr33ord1

Interesting that (per the video) the pipe appears to have two joints in it. I wonder why. Another question: Is the vent pipe for the black tank as close to the roof level? The grey tank vent pipe is closer than I'd expect.

The Gray and Black tank vent pipes coming out of the roof are the exact same height.

As I said before, if it's a question of establishing that the main vent is the problem, pulling the p-traps after filling the tank above the problem level, and then dumping the tank, should be a sufficient test.

Are you saying I should fill the tank until it backs up into the tub, empty it, THEN pull the p-traps?.....honestly, I think that is the only thing we HAVEN"T tried yet....but am I understanding you correctly in the order of trying this?

And again, thank you so much for your efforts in helping

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[Lrakeahs]

Originally Posted by coachmanjay

It appears that the problem is not with the tank not draining but that the water level when the tank is 2/3 full is above the elevation of the tub/shower drain.

Exactly...........the tank holds 36 gallons and is only taking in approx. 20 gallons before it backs up into the tub/sink. With the gauge reading at 2/3 full.

We bought the trailer brand new....we have been camping around 10 times, with absolutely no issues.....then the incidence with the gray tank happened, and ever since we have been having this issue.

Maybe the 2 aren't connected and it's just a coincidence.....

So far we have checked the gray tank vent pipe with the endoscope..took video as posted...we removed the plumbing outside that leads into the gray tank....looked around, took pictures as posted....checked those valves (whatever they are called) that sit on top of the plumbing in the kitchen and bathroom sink pipes, could one of those be bad, even though they look fine, my husband removed both of them and blew into them and checked them over and said they look ok....could one be bad and cause that problem.....?

The gray tank looks level and the plumbing coming out of the gray tank is level, the tank drains perfectly....

If we empty the p-traps so all the lines are clear and open, all water removed from the entire system...then start all over like factory, could that help?

Wish there was a factory reset button.....lol....

The system is not so complicated, we have checked everything we can think of and the issue remains........

One thing we did learn NOT to ever do again...... my brother-in-law told hubby to plunge the tub and sinks.....which he did.....oy vie.....the pressure of doing that I guess broke the seal on the bathtub and that leaked water all underneath the tub.....so now we have to re-seal that and hope we don't have any hidden leaks any where..ok, so won't be doing that ever again!!!

This is truly a mystery that is driving me bonkers

You guys, thank you so much for your time, appreciate it more than you'll ever know........

Any other suggestions?

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[coachmanjay]

Still think it is an elevation issue, the tank maybe higher than before or you never filled the tank previously. You might try emptying the tank than running water in the tub until it does not drain and check how full the gages say the tank is or measure the amount of water that drains, if about 20 gallons that confirms the problem

[l1v3fr33ord1]

As I said before, if it's a question of establishing that the main vent is the problem, pulling the p-traps after filling the tank above the problem level, and then dumping the tank, should be a sufficient test.

Are you saying I should fill the tank until it backs up into the tub, empty it, THEN pull the p-traps?.....honestly, I think that is the only thing we HAVEN"T tried yet....but I am understanding you correctly in the order of trying this?

As I've since said in my post #29, I don't believe there is a blockage problem in the roof vent.

However, what is quoted above is an idea on how to check if a roof vent is blocked, without taking the cap off or using a camera or similar more invasive steps. The process would be:

1) Empty the tank
2) Close the tank outlet valve
3) Fill the tank until it backflows into the tub
4) With buckets underneath, remove the p-traps beneath the kitchen and bathroom sinks. Make sure no water is in the traps.
5) Open the tank outlet valve

This procedure turns the sink drain lines into "extra" vents. If water comes flying out of the tank using this procedure, but does not do so when the p-traps are connected and filled, then it means the roof vent is likely blocked.

The air admittance valves (AAVs), are supposed to provide an "extra" measure of venting. However, by disconnecting and draining the p-traps we eliminate the assumption that the AAVs work correctly. You could perform the same test as removing the p-traps by removing the AAVs under the two sinks. I just find them harder to reach than the p-traps.

Anyway, it was just an idea. As you have pictures/videos of your tank and vent interiors, you already know the roof vent is not blocked.

[slowmachine]

Ignore the tank gauge reading. It is only telling you that the tank is at least 2/3 full, but not completely full.

If you can use the camera to view the inside of the tank when it is full to the point where it is backing-up into the tub, you may be able to see if the tank actually IS full.

If it really is full, then the most logical explanation is that the earlier incident has altered the support structure for the tank and crushed it to the point where the tank capacity is significantly reduced.

If the tank is not really full, you have a vent problem that needs more attention.

[coachmanjay]

If I understand the problem it is not so much as not draining but backing up in the tub before the tank is full.

[Lrakeahs]

Originally Posted by coachmanjay

If I understand the problem it is not so much as not draining but backing up in the tub before the tank is full.

Yep, exactly.....