Hidden trap-literally

[gmillerok1]

I have to keep my van outside during the winter. I am very careful to winterize the unit at the first hint of freezing using anti-freeze.

This year, I de-winterized the unit and took a trip, and after I dumped the tanks, I hooked up the shower hose to the flush line to flush out the black tank like I always do (it's a great feature). What I didn't expect next was the torrent of water flowing out from underneath and down the side of the van.

Upon inspection, I discovered a check-valve located inside the van in this line had broken off completely from the plumbing, so I was flushing out the inside of my van instead of the black tank. This valve is located at the top of the pex tubing, and has a 90 degree angle back to another pex pipe that goes down to the floorboard and then under the floor to the black tank. The check valve has a small valve which is opened when the water is on, and closed when not. It has a vacumm breaker which should allow water to flow out of the line into the tank thus emptying the line. The problem is that it holds a bit of water unless the valve is pointed quite a bit downwards-and mine was not-and so it froze breaking the fixture, which isn't too sturdy to begin with. Nowhere in the AS manual is there any information about winterizing this line. To inspect it takes removing a drawer, a mirror and some gymnastics, but it can be down-that's how I found it. To fix it requires removal of the microwave in my model.

So, a word to the wise-if you leave the van outside subject to freezing temperatures, be sure to winterize the flush line in addition to the other lines or you risk the same issue. Pictures of this valve which show what happened and location can be found in the Yahoo Interstate group if anyone is interested.

Gerald

[Protagonist]

Originally Posted by gmillerok1

I have to keep my van outside during the winter. I am very careful to winterize the unit at the first hint of freezing using anti-freeze.

This year, I de-winterized the unit and took a trip, and after I dumped the tanks, I hooked up the shower hose to the flush line to flush out the black tank like I always do (it's a great feature). What I didn't expect next was the torrent of water flowing out from underneath and down the side of the van.

Upon inspection, I discovered a check-valve located inside the van in this line had broken off completely from the plumbing, so I was flushing out the inside of my van instead of the black tank. This valve is located at the top of the pex tubing, and has a 90 degree angle back to another pex pipe that goes down to the floorboard and then under the floor to the black tank. The check valve has a small valve which is opened when the water is on, and closed when not. It has a vacumm breaker which should allow water to flow out of the line into the tank thus emptying the line. The problem is that it holds a bit of water unless the valve is pointed quite a bit downwards-and mine was not-and so it froze breaking the fixture, which isn't too sturdy to begin with. Nowhere in the AS manual is there any information about winterizing this line. To inspect it takes removing a drawer, a mirror and some gymnastics, but it can be down-that's how I found it. To fix it requires removal of the microwave in my model.

So, a word to the wise-if you leave the van outside subject to freezing temperatures, be sure to winterize the flush line in addition to the other lines or you risk the same issue. Pictures of this valve which show what happened and location can be found in the Yahoo Interstate group if anyone is interested.

Gerald

Much appreciated. I hadn't considered that. I knew about the check valve, but never considered it would trap water. Guess I'm just fortunate that the New Orleans area had such a mild winter that I never had to winterize this year, or I might have had a "me too" tale to tell.

[Lily&Me]

Boooo!

Sorry for your troubles!


Maggie

[gmillerok1]

I replaced the check valve and tested it out. A few drops of water occasionally would drip out of the top but not enough to be a problem. But what I did determine is that the valve has two valves. One moves up when the water is on. The other is at 90 degrees and moves horizontally when the is water flowing and it has a spring closing the valve when the water is shut off. When the hose is disconnected, the water under the first valve empties back down the tube. However, since there other side is closed, there is no way to relieve the pressure, so the tube remain full of water.

So, let this be a warning: Winterize the black tank flush-out plumbing as it will definetly freeze no matter what orientation the check-valve may be!

I wonder what other surprises Airstream has for me. This one is inexcusable.

Gerald

[dkottum]

I always get a bit anxious when using the flush, hearing the sound of the water blasting inside the tank (holy crap, is where is all that water going?)

Would blowing out the line from the hose hookup clear the water from the check valve?

doug k

[gmillerok1]

Originally Posted by dkottum

I always get a bit anxious when using the flush, hearing the sound of the water blasting inside the tank (holy crap, is where is all that water going?)

Would blowing out the line from the hose hookup clear the water from the check valve?

doug k

I seriously doubt it would because the spring requires a lot of pressure to open the valve. I would not rely on that method.

I really have to wonder why the valve is needed. I guess it is required to isolate the waste tank from the city hookup.

GM

[masseyfarm]

I agree that it is good practice to clear the 'black water flush' line.
I detailed it in a post on this thread.

http://www.airforums.com/forums/f313/winterize-pink-stuff-rv-antifreeze-drain-and-flush-71784.html#post1203191

Dave

[dznf0g]

Originally Posted by gmillerok1

I seriously doubt it would because the spring requires a lot of pressure to open the valve. I would not rely on that method.

I really have to wonder why the valve is needed. I guess it is required to isolate the waste tank from the city hookup.

GM

I was waiting for this question to pop up. This is an anti-siphon valve required for MANUFACTURERS to prevent the UNLIKELY siphoning of black water all the way back into the public water system.

Mine leaked badly when I got my AS. I called the manufacturer of the valve and was asked. "Why would you replace it? Just bypass it with a section of hose and be done with it." That's what I did.

1) The line routing is well above the top of the black tank.
2) Unless you completely fill the black tank with the flusher, a siphon action is very unlikely as the water level in the tank is below the spray head.
3) I use 75' of garden hose (never to be used for anything close to potable water) to flush the black tank. The likely hood of bacteria getting all the way up to the spigot is very remote.
4) There is an additional anti-siphon valve at the black tank flusher hose connection.

This is a very poor design valve (the clear inside one). They not only can crack from freezing, but the air gap valve itself is prone to not seating and sealing properly. That's what mine did and it flooded the inside of the AS pretty good before I caught it.

[polarlyse]

I blow the tank washer with compressed air when I winterize. Not sure if it holds any water to freeze or not but it's a simple thing to do. So why not.

[gmillerok1]

Originally Posted by dznf0g

4) There is an additional anti-siphon valve at the black tank flusher hose connection.

That's the one on mine that froze. Where is the other one located so I can check on it as well, if there is another one on the Interstate?

GM

[dznf0g]

This is the one I thought you were talking about, and the one I removed from the system as they are notorious leakers

[gmillerok1]

Originally Posted by dznf0g

This is the one I thought you were talking about, and the one I removed from the system as they are notorious leakers

Attachment 182274

That's it, alright. But are there more than one of these things on there somewhere besides next to the inlet?

GM

[dznf0g]

Originally Posted by gmillerok1

That's it, alright. But are there more than one of these things on there somewhere besides next to the inlet?

GM

No, the other one is of a different design and is built into and inside of the black connector where you attach the garden hose. It is just a simple duck bill type flapper valve, I believe.

Edit: I see now that you have an Interstate....It may be set up quite differently than my trailer. The valve in my unit was probably about 3 feet from the water inlet hookup.