Sundance 241BH - Black water tank fell out

[bedpan]

Hey Folks,

Got a new 2018 Sundance 241BH. We picked it up a few weeks ago and just finished up our first trip. We drove from the Toronto area down to Cape Canaveral Fl. In total 5050km including some driving around down there not hooked up. The first day we pulled into the park I went about setting up and inadvertently connected the fresh water hose to the black water flush out. A few minutes later we heard a loud bang and shutter to find the black water tank sitting on the ground.

Fortunately the toilet had only been used for a couple emergency pee's on the drive south so there was no major mess to clean up. I was able to put everything back together and it all appears to be working fine.

What I am wondering is why the tank would fall out. As far as I can tell the tank pressurized and swelled. When it swelled it got narrower as it got taller and fell from the brackets holding it in place. There did did not appear to be a lot of water in there. Far less then the 30 gallons that it should be able to hold (saying that I am not positive though, maybe it was 30 gallons). The tank itself was not damaged at all the brackets holding it were not bent at all.

In my mind the tank is vented to the roof. Should the tank not filled to capacity then turned the trailer into a water feature spraying water out the vent? Is there some sort of check valve to prevent this?

What I am really wondering is there a venting issue that needs to be resolved now?

Any thoughts are appreciated.

As a side note I have not refilled the tank to capacity to confirm the brackets are able to support the weight. Due to our only being in Fl for a 5 nights I thought it best to leave it alone. Come spring here I plan on filling the tank to capacity to confirm it will not fall out. Also there the fresh water tank which is 44 Gallons has bars underneath it to support it where the grey and black tanks do not.

Side side note.. Seeing the tank laying on the ground it reminded me of this video "front of the boat fell off"

Why did the tank fall off?

[4x4van]

bedpan wrote:
I will be there this week or early next... I will see what they have to say...

Thanks..

dougrainer wrote:

4x4van wrote:
??? I've never heard of a floating check valve in a black (or grey) tank vent. I can see no reason for a manufacturer to install one; The only way to "overfill" the black tank is with the rinser, and in that case, it would be better to have the overflow go out onto the roof rather than overpressurizing and dropping (like yours did) or even splitting the black tank open, or flowing out through the toilet (or bathroom sink if plumbed that way). Sounds like a made-up excuse by the dealer. :S

Have that dealer show you that floating check valve. In 40 years working on RV's and dropping countless tanks, I have NEVER seen anything inside a tank or connected to a Vent system in or around the tank. Every week, I think I cannot find something new that a Dealer/Tech/ customer posts that is BS. Well, this makes my week:B Doug

If he says that he can't show it to you since it's hidden from view, ask to see one in an RV parts catalog. :E

Additionally, the dealer SHOULD reimburse you for whatever you spent adding angle iron/straps to actually support the tank; which is something that should have been done by the factory.

[bedpan]

I will be there this week or early next... I will see what they have to say...

Thanks..

dougrainer wrote:

4x4van wrote:
??? I've never heard of a floating check valve in a black (or grey) tank vent. I can see no reason for a manufacturer to install one; The only way to "overfill" the black tank is with the rinser, and in that case, it would be better to have the overflow go out onto the roof rather than overpressurizing and dropping (like yours did) or even splitting the black tank open, or flowing out through the toilet (or bathroom sink if plumbed that way). Sounds like a made-up excuse by the dealer. :S

Have that dealer show you that floating check valve. In 40 years working on RV's and dropping countless tanks, I have NEVER seen anything inside a tank or connected to a Vent system in or around the tank. Every week, I think I cannot find something new that a Dealer/Tech/ customer posts that is BS. Well, this makes my week:B Doug

[dougrainer]

4x4van wrote:
??? I've never heard of a floating check valve in a black (or grey) tank vent. I can see no reason for a manufacturer to install one; The only way to "overfill" the black tank is with the rinser, and in that case, it would be better to have the overflow go out onto the roof rather than overpressurizing and dropping (like yours did) or even splitting the black tank open, or flowing out through the toilet (or bathroom sink if plumbed that way). Sounds like a made-up excuse by the dealer. :S

Have that dealer show you that floating check valve. In 40 years working on RV's and dropping countless tanks, I have NEVER seen anything inside a tank or connected to a Vent system in or around the tank. Every week, I think I cannot find something new that a Dealer/Tech/ customer posts that is BS. Well, this makes my week:B Doug

[4x4van]

??? I've never heard of a floating check valve in a black (or grey) tank vent. I can see no reason for a manufacturer to install one; The only way to "overfill" the black tank is with the rinser, and in that case, it would be better to have the overflow go out onto the roof rather than overpressurizing and dropping (like yours did) or even splitting the black tank open, or flowing out through the toilet (or bathroom sink if plumbed that way). Sounds like a made-up excuse by the dealer. :S

[bedpan]

Well thought I would update in case anyone was interested...

We just had our second trip with the trailer. The first was about 3500 miles that the tank fell out. This trip was about 1500 miles. Black tank wise we were problem free. Everything worked as designed and I hooked up the hoses right!

I did talk with the dealer before this trip. As per the service guy there is a floating check valve on the vent that prevents water from flowing up the pipe. If this is true it explains the issue. The tank became full, the check valve closed and the tank swelled until it fell out of the brackets. Out of an abundance of cation I did but some angle iron and put two straps under the tank to prevent it from falling out again.

We did have some other water leaking under the floor issues. The TT is back with the dealer now getting those resolved. Or I hope they are getting resolved anyways!!

Cheers,

Mike

[bedpan]

For clarity sake, I do not know if the tank was full or not. I don't think so, but I did not measure the water on the ground. I can say I had no water coming of the roof that would indicate that water was flowing out of the vent.

The fresh water tank has 3 support brackets that run underneath of the tank. The Grey and black have not brackets that support underneath and have only the mounting brackets under the sides of the tank.

As mentioned I have 3 things to do.

Have a discussion with the dealer to get there opinion on things. This will include informing them about what happened and how it happened.

Run water down the vent to check for obstructions in the vent pipe. I will do this while checking the 45 degree bend and the fitting into the tank for any leaks.

Fill the tank to capacity and see what happens...


I should also mention. It has been suggested that the black water pipe could have slid into the tank and sat on the bottom preventing the venting from occurring. Because of the supports around the 45 degree bend I don't believe this occurred. While installing the tank I could not pull the vent piped down or push it up more then about 1 inch. It is fastened at some point in the while or the cap at the roof.

This again leaves me with the vent is clogged, or the tank fell out under its own weight... I cannot see any other options. I will gladly take suggestions though...


Cheers,

Mike

4x4van wrote:
IF the tank is overfilled and the vent pipe is completely filled all the way to the roof, it will only exert about 3 psi, not 45 psi. (Water weighs 0.036127 lbs/cu. in., and there is less than 148 cu. in. of volume in a 7' x 1.5" pipe; that equals just 5.36 lbs, or 3 psi) But since there was no water coming off the roof, that means that the vent pipe was NOT filled with water. The OP also says that the tank never filled completely.

In any case, the tank fell out, which should never have happened. If the tank "expanded" because of pressure, then there was an obstruction in the vent pipe. If the tank dropped out simply because of the weight of a nearly full tank (which changed the shape), then there is a major problem with the tank supports.

Since every RV I've owned over the past 30 years has had the tank(s) supported with much more than just L brackets along the sides, my gut says that the manufacturer left out some additional supports that should've spanned the bottom of the tank. Filling a long/wide, but short tank without supporting the bottom will obviously result in the bottom of the tank sagging, and that sagging pulled the sides in enough to slip past the L-brackets supporting the edges of the tank.

At least that's how I'm seeing it, YMMV.

[4x4van]

IF the tank is overfilled and the vent pipe is completely filled all the way to the roof, it will only exert about 3 psi, not 45 psi. (Water weighs 0.036127 lbs/cu. in., and there is less than 148 cu. in. of volume in a 7' x 1.5" pipe; that equals just 5.36 lbs, or 3 psi) But since there was no water coming off the roof, that means that the vent pipe was NOT filled with water. The OP also says that the tank never filled completely.

In any case, the tank fell out, which should never have happened. If the tank "expanded" because of pressure, then there was an obstruction in the vent pipe. If the tank dropped out simply because of the weight of a nearly full tank (which changed the shape), then there is a major problem with the tank supports.

Since every RV I've owned over the past 30 years has had the tank(s) supported with much more than just L brackets along the sides, my gut says that the manufacturer left out some additional supports that should've spanned the bottom of the tank. Filling a long/wide, but short tank without supporting the bottom will obviously result in the bottom of the tank sagging, and that sagging pulled the sides in enough to slip past the L-brackets supporting the edges of the tank.

At least that's how I'm seeing it, YMMV.

[road-runner]

I confess that a few years ago when I was either distracted or not thinking clearly, I was running the black tank flusher with the drain valve closed, and didn't notice until water was running off the roof. The water was clear because the rig had just come out after winter. When the black tank is empty, I always use the flusher to add a few gallons of water. I learned to not let my mind wander when doing this. Considering the flow capability of the vent pipe compared to the flow of the flusher, there's no way the tank pressure could be more than what's caused by the height of the vent.

[Lynnmor]

Bedpan, I am in agreement with what you have said, but plumbers putty is a poor way to seal connections. The intended use of plumbers putty is for setting fixtures so that water doesn't run in if there is a gap.

More and more trailers are built in a manner that is not roadworthy and tanks that aren't secured well should be reported to the NHTSA.

[bedpan]

Hey Doug...

Your experience means you bring a lot of insight, talking about my honesty does not much help things. Regardless of my honesty the obvious problem I have fixed with my own time and money. It was a cheap fix, about $20 for a 2x4 for cribbing while I installed, plumbers putty and some spray foam to seal things up around the drain.

It's not the obvious problem I am now trying to fix. Its the root cause.

1) The tank is not properly vented. I reconnected the 1.5" ABS pipe to the rubber boot when I was installing the tank. The pipe 45's just above the tank and enters a wall and goes to the roof. Is there an obstruction in the pipe preventing air flow or a complete obstruction. I will test this myself by running some water down the vent to see what happens. There is not reason the water should not flow freely from the vent to the tank

2) The tank was not installed properly and it fell out under its own weight as it filled. I will also test this by filling the tank to the rim and seeing what happens.


In your mind and experience Doug, am I missing anything? You have seen similar things before, should I have any concerns about the tank? Whats the best way to wet test the tank to be sure it is water tight?

One more question... When I sealed the large drain pipe to the tank I tried to follow what I saw. The pipe is attached with a pipe clamp and copious amounts of plumbers putty. I used some new plumbers putty around the flange of the tank before I slid the pipe on top. Then tightened up the pipe clamp. There was black spray foam in around the tank and pipe. I used some standard large void spray foam from home depot to mirror this.

Did I miss anything?

Cheers and thanks!

Mike

[Ralph_Cramden]

wnjj wrote:

dougrainer wrote:
IF the OP is HONEST and tells the Dealer what happened, then odds are the factory will deny any warranty. It is not the dealer that makes the decision on covered warranty items, it is the Factory. The fact is, the OP did something wrong, and he should shoulder blame and cost. Doug

There's nothing wrong with filling the black tank with fresh water, even if through an non-standard means. The flow rate of the hose should be easily offset by the vent. If it cannot handle being full of water with 5 psi, it never will when travelling down the road.

If the tank is repaired under warranty the HONEST RV dealer service department takes what the RV manufacturer is willing to pay.

If the HONEST RV dealer can find a way to blame the customer and the HONEST RV Manufacturer denies the claim, the HONEST RV Dealer Service Department can then dippity doo dah into the customers pocket for full effect......CA-Ching. Possibly they can swindle the customer into purchasing a worthless service contract or doing a sealtest and recaulk job that is not needed while they're there running the service gauntlet.

Ahhhh yes, the HONEST RV Dealer and RV dealer Service Dept.

[wnjj]

dougrainer wrote:
Offset??? Fill your Black tank to full with the water coming up the toilet tube. Shut off the water, open the Toilet to flush, let it close, Then start the Black flush again. Wait 1 minute, Then flush the toilet. Hope you have a rain suit on as the water will spray all over the bath and ceiling of the bath. ALL from that supposed 5 psi:B

Offset means the vent is large enough to handle the incoming flow RATE.

You’re completely confused when it come to water pressure. There is 45 psi available in the water system but flowing it into an open container doesn’t cause 45psi of pressure in the container. When it fills up, there is not much more than the static pressure of the water column rising in the vent. That is calculated roughly as 62 lbs (1 cu ft of water)/144 sq in. or a little under 0.5 psi per vertical foot. Now if there is a significant restriction in the exit (vent), higher pressure can build. That is how a garden hose nozzle works.

[dougrainer]

Offset??? Fill your Black tank to full with the water coming up the toilet tube. Shut off the water, open the Toilet to flush, let it close, Then start the Black flush again. Wait 1 minute, Then flush the toilet. Hope you have a rain suit on as the water will spray all over the bath and ceiling of the bath. ALL from that supposed 5 psi:B

[dougrainer]

bedpan wrote:
My thoughts as well, thanks wnjj..

I will have a discussion with the dealer at some point when I have sometime... The reality is it maybe easier for me to fix the vent, or add supports then the time it takes to hookup and drive 45 minutes up the road twice, to drop off and then pickup. Worth the discussion non the less..

wnjj wrote:

dougrainer wrote:
IF the OP is HONEST and tells the Dealer what happened, then odds are the factory will deny any warranty. It is not the dealer that makes the decision on covered warranty items, it is the Factory. The fact is, the OP did something wrong, and he should shoulder blame and cost. Doug

There's nothing wrong with filling the black tank with fresh water, even if through an non-standard means. The flow rate of the hose should be easily offset by the vent. If it cannot handle being full of water with 5 psi, it never will when travelling down the road.

You BOTH are missing the facts. It is NOT 5 PSI. Filling the Black tank with fresh water is a standard practice to flush the tank. That is what it is designed to do. BOTH of you need to read the Owners manual. AND, on some RV's it is stated by a sticker by the Black fill. YOU MUST LEAVE THE BLACK TANK VALVE OPEN WHEN USING THE BLACK FLUSH. Now, granted very few ever do that. BUT, the OP filled the tank PAST capacity and expanded the tank beyond its design. The water input is in EXCESS of 45 PSI, that is standard water pressure. Where you get fixated on 5 PSI, I have No IDEA. I have 40 years and still working as a RV Tech. I think I know a LOT more about this than either of you. As, I have seen this type problem numerous times over the years. Doug

PS. TELL the dealer what you did. I will bet you will NOT. Honesty is funny when it costs YOU money.