Potential Full Black Water Tank Problem

[vicsryd]

I was filling/flushing the black water tank after dumping and got distracted by a phone call. Next thing I know water is coming out from the seams of the black water "sealed" compartment over the LP tank.

To my surprise when I opened the toilet to see how full the tank really was I was surprised to find it was somewhat pressurized. I didn't think that could happen given the tank vent, etc. I assume this pressurization caused the water to be pushed out a connection point (e.g. between the toilet and the tank). I checked the vent with water running into the tank and I can clearly hear what's going on via the vent.

I took the cover off (no small feat given the copious amounts of soft gasket material) and just in case sprayed it down with vinegar to disinfect and after a while blew it all out with the air hose.

Picture of black (left) and grey (right) tanks on passenger/LP side of coach.


My questions to my peers are:

First, what should happen when the black water is full? I assume it's legally not supposed to just overflow onto the street via an overflow tube but just leaking out as it did doesn't seem right either.

Second, is the pressurized state I found an indication of a larger problem?

Third, there is an overflow hose (garden hose material) that comes down through the floor from the house near the grey water tank. What is this for?

Thanks in advance.

[vicsryd]

I was filling/flushing the black water tank after dumping and got distracted by a phone call. Next thing I know water is coming out from the seams of the black water "sealed" compartment over the LP tank.

To my surprise when I opened the toilet to see how full the tank really was I was surprised to find it was somewhat pressurized. I didn't think that could happen given the tank vent, etc. I assume this pressurization caused the water to be pushed out a connection point (e.g. between the toilet and the tank). I checked the vent with water running into the tank and I can clearly hear what's going on via the vent.

I took the cover off (no small feat given the copious amounts of soft gasket material) and just in case sprayed it down with vinegar to disinfect and after a while blew it all out with the air hose.

Picture of black (left) and grey (right) tanks on passenger/LP side of coach.


My questions to my peers are:

First, what should happen when the black water is full? I assume it's legally not supposed to just overflow onto the street via an overflow tube but just leaking out as it did doesn't seem right either.

Second, is the pressurized state I found an indication of a larger problem?

Third, there is an overflow hose (garden hose material) that comes down through the floor from the house near the grey water tank. What is this for?

Thanks in advance.

[Tom N]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> just in case sprayed it down with vinegar to disinfect </div></BLOCKQUOTE>
Vinegar is not a disinfectant.

Water should come out the roof vent when your tank is full from flushing.

[FrontRangeRVer]

If you flush your black water tank out WITHOUT having the drain opened, that will pressurize your tank. All the late model Winnebagos are like this.

[Captain Bud]

I don't want to disagree with you, however I flush my black tank with the drain valve closed and I NEVER pressurized my tank. I drain it, close the valve let it flush out some and then drain it again. How can you pressurize a tank that is direct vented to the roof???

[FrontRangeRVer]

During PDI of our new unit, I was told emphatically that using the flush fitting while not having the valve open will pressurize your black tank. He said they have several repairs a month because of this.

Check with Winnebago, they will tell you the same thing....

[mrsr71]

I agree with Captain Bud. I follow the procedure he uses and I've never had a problem

[Tom N]

You can't pressurize the black tank because it is always vented through the roof vent.

[Tom N]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by FrontRangeRVer:
During PDI of our new unit, I was told emphatically that using the flush fitting while not having the valve open will pressurize your black tank. </div></BLOCKQUOTE>

Who is your dealer???

[Ed Gardiser]

While flushing the black tank I noticed water dripping and then running out onto the ground down thru the storage compartments. This was on the other side from the flush connection, near the toilet location.I removed the magazine rack to find a vacuum breaker/check valve installed in the black tank flush line.The check valve must have stuck closed causing the vacuum breaker to purge the potable water.Since then I have replaced the vacuum breaker and check valve.
Ed Gardiser
Escondido,Ca.
04 Vectra
87 Nissan PickUp
FMCA

[vicsryd]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Tom N:
Vinegar is not a disinfectant.

Water should come out the roof vent when your tank is full from flushing. </div></BLOCKQUOTE>
Vinegar may not be as effective aa bleach but it does qualify as a disinfectant and it' safe and doesn't oxidate materials. See this article for more information.

I agree with a roof vent the tank should not pressurize per se and overflow should go up the stack. With this in mind I can see trace evidence the leak occurred where the vent stack attaches to the tank.

We've never had an odor problem and have the venturi type vent caps. It will be interesting to see if we now experience an odor problem by having compromised where the stack is cemented to the tank (if in fact it ever was).

[FrontRangeRVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Tom N:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by FrontRangeRVer:
During PDI of our new unit, I was told emphatically that using the flush fitting while not having the valve open will pressurize your black tank. </div></BLOCKQUOTE>

Who is your dealer??? </div></BLOCKQUOTE>

Not sure the dealer's name matters, but it is a very large Winnebago dealer.

I thought it sounded odd that the black tank would pressurize when the PDI guy told me that, but I blew it off as I have owned many motorhomes and never heard of that....

[dawg]

The garden hose is the drain from your refrigerator.
I over filled the black tank once, and the rubber gasket on the top of the tank split.

[vicsryd]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by dawg:
I over filled the black tank once, and the rubber gasket on the top of the tank split. </div></BLOCKQUOTE>
Do you mean the gasket at the vent stack?