Black water flush

[taken]

A vacuum breaker (also called a backflow preventer) keeps black water out of your hose should there be a drop in pressure in the park water system.

[arpipeliner]

Originally Posted by OldCoot

Can or will you explain what good they are in the first place?

I understand the liability factor of FR. I will pay money to see crap water get siphoned to a wobbly, multiple jet head fitting that restricts water flow to make pressure go back up six feet high.

Trust me six foot of garden hose was the arkansas credit card for us.


Sent from my iPhone using Forest River Forums

[OldCoot]

Originally Posted by taken

A vacuum breaker (also called a backflow preventer) keeps black water out of your hose should there be a drop in pressure in the park water system.

There is a back flow preventer at the back of the outside hose connection.

[taken]

I think, and Bob will correct me if I'm wrong, trailers with black tank flush have to have both the vacuum breaker and the a simple check valve back flow preventer. Perhaps it's an RVIA rule to have double protection? The plastic vacuum ones are cheap and are often placed under the bathroom sink to get the 2+ foot height above the tank needed to function correctly. Many eliminate them as the possibility of sewage climbing up that tube and into a fresh water hose is relatively small. Others replace them with brass models used on home hot water tanks that are much less likely to fail. When they fail, one of two things happens. Water won't flow through as discussed earlier. Alternately, they come apart giving your bathroom floor a bath. The latter happened to me on a brand new Keystone Cougar High Country I bought back in 2011 during it's first use.

I think the real problem is the quality of a part that isn't' really necessary and is just there to meet regulations, is never very high...

[OldCoot]

Originally Posted by taken

... Many eliminate them as the possibility of sewage climbing up that tube and into a fresh water hose is relatively small...

Relatively impossible, as the black tank flush is not connected to the fresh water lines anywhere.

[taken]

Originally Posted by OldCoot

Relatively impossible, as the black tank flush is not connected to the fresh water lines anywhere.

No one said anything about fresh water lines in the trailer. What I was referring to is the fresh water hose feeding the black tank flush being connected to the campgrounds fresh water supply. That is what the check valves are there to protect. Not the RV.

[bulletbob]

The back flow preventer inside the unit is required by the manufacturer and rvia. Taken is correct about protecting the parks wster. Also there should only be a check valve on your city water/tank fill fitting. Not the black tank flush connection.

[OldCoot]

Originally Posted by taken

No one said anything about fresh water lines in the trailer. What I was referring to is the fresh water hose feeding the black tank flush being connected to the campgrounds fresh water supply. That is what the check valves are there to protect. Not the RV.

My Flagstaff has a back flow preventer just inside the trailer on the black tank input line. I removed the leaking vent under the vanity and about 10' of hose.
I fail to see where a decrease in the flush input line would let fluid from the black tank back into the input line with the black tank not being pressurized.

[taken]

Regulations don't always make sense. Remember, in our litigious society, we are constantly being protected from ourselves... whether we need it or not... If there is a one in a million shot something bad will happen, we need a rule to prevent it...

[OldCoot]

Originally Posted by bulletbob

The back flow preventer inside the unit is required by the manufacturer and rvia. Taken is correct about protecting the parks wster. Also there should only be a check valve on your city water/tank fill fitting. Not the black tank flush connection.

Well bulletbob, that might be true on the XLR units, but I can assure you that my Flagstaff has a backflow preventer on the BLACK TANK flusher. I will take pictures if you so desire.

[OldCoot]

Originally Posted by bulletbob

The back flow preventer inside the unit is required by the manufacturer and rvia. Taken is correct about protecting the parks wster. Also there should only be a check valve on your city water/tank fill fitting. Not the black tank flush connection.

Black tank flusher check valve.

[MN John]

I took another look at my black tank flush issue last night. Remove the input water regulator which was set to 40 psi and filter that was on the hose, therefore supplying about 60 psi from the house regulator. I tried this just in case the vacuum breaker or a check valve needed additional pressure to function….but no luck.

Then removed the vacuum breaker (image off the web) from under the sink…found it to be “bone dry” whereas I would assume that at least a small drop of water would be present on the inlet side if water was getting to it (?). It would make an internal clicking sound if I shook it, but couldn’t get air to pass by blowing into it (however, my psi is likely very low considering blowing up a balloon is a challenge these days). Reinstalled….but no luck.

Looked but couldn’t find a check valve that I assume is installed somewhere between the black flush input connection and the vacuum breaker. The hose connected to the input connection runs up to the frame and then into the under belly. No check valve in site (?).

Conducting our “shakedown maiden voyage” this weekend…. so went to plan B by picking up (at a dealer that’s close to me, but not where I bought the RV) one of those handheld sprayers that you stick down the toilet. That will work till I figure it out, or stop at the dealer for repair.

Other than this minor issue, everything else seems to be working great! First true test this weekend…especially since the low Friday night is forecasted at 33 degrees.

[taken]

I'm guessing you have a pinched line if no water is making it to the vacuum breaker?

[stevejd235]

Originally Posted by MN John

...First true test this weekend…especially since the low Friday night is forecasted at 33 degrees.

As a follow Minnesotan, I love to see people out camping in these temps. I can't want for my new TH to be here are the end of the month.

Happy camping...

[GreenImp]

Originally Posted by bulletbob

The back flow preventer inside the unit is required by the manufacturer and rvia. Taken is correct about protecting the parks wster. Also there should only be a check valve on your city water/tank fill fitting. Not the black tank flush connection.

My 2013 Rockwood 8289WS does not have any valves directly behind any of the fittings. So is this check valve present only when your city water connection also fills your fresh water tank, or should I have something that I don't?

Thanks to OC for posting the above picture. I have been wondering about this for a while now. Your picture made it easy.

[MN John]

Originally Posted by stevejd235

As a follow Minnesotan, I love to see people out camping in these temps. I can't want for my new TH to be here are the end of the month.

Happy camping...

Only 15 miles from home, so if the furnace, my long Johns, and or my wife all fail me…it’s a short trip home! Looking forward to it rebounding to the mid-60s on Saturday.

[Witch Doctor]

Originally Posted by GreenImp

My 2013 Rockwood 8289WS does not have any valves directly behind any of the fittings. So is this check valve present only when your city water connection also fills your fresh water tank, or should I have something that I don't?

Thanks to OC for posting the above picture. I have been wondering about this for a while now. Your picture made it easy.

Unless they made a change between 2011/2013, All you have is a black tank vacuum break, located behind the shower handles and your water pump by-pass for city water hook-up. I know of no black flow preventer in the fresh water tank line except your overflow air line. Those are the only two I have found and I have looked all over. Unless I missed something but I don't think so, I have been all through the plex and white hose lines. Both the black tank flush vacuum break and the water tank fill line and discharge back to the pump are white water hose. If there was a backflow preventer in your FW line. When you over fill you would only see water coming out of the overflow not the fill line also. You would see water at first coming out the fill line. If you let it run you will see a constant flow of water still coming out the overflow line and the fill whole. If the check valve closed then you would also stop the overflow. Try it the overflow will run until you shut the water off.

[OldCoot]

My city water & black tank flush BOTH have back flow preventers just inside the trailer behind the hose connection. There is not freshwater back flow preventer as it is a "stick the hose in" type fill with a vent to the side. Anyone need pictures?

[stevejd235]

Originally Posted by MN John

Only 15 miles from home, so if the furnace, my long Johns, and or my wife all fail me…it’s a short trip home! Looking forward to it rebounding to the mid-60s on Saturday.

I hear you on the temps. The cycle ride to work these past few mornings have been on the chilly side (temps in the low 30's, speed around 65, windchill right around 13). Luckily, we have the right gear for camping or riding the cycle in these temps....

[bubbles]

Originally Posted by MN John

I took another look at my black tank flush issue last night. Remove the input water regulator which was set to 40 psi and filter that was on the hose, therefore supplying about 60 psi from the house regulator. I tried this just in case the vacuum breaker or a check valve needed additional pressure to function….but no luck.

Then removed the vacuum breaker (image off the web) from under the sink…found it to be “bone dry” whereas I would assume that at least a small drop of water would be present on the inlet side if water was getting to it (?). It would make an internal clicking sound if I shook it, but couldn’t get air to pass by blowing into it (however, my psi is likely very low considering blowing up a balloon is a challenge these days). Reinstalled….but no luck.

Looked but couldn’t find a check valve that I assume is installed somewhere between the black flush input connection and the vacuum breaker. The hose connected to the input connection runs up to the frame and then into the under belly. No check valve in site (?).

Conducting our “shakedown maiden voyage” this weekend…. so went to plan B by picking up (at a dealer that’s close to me, but not where I bought the RV) one of those handheld sprayers that you stick down the toilet. That will work till I figure it out, or stop at the dealer for repair.

Other than this minor issue, everything else seems to be working great! First true test this weekend…especially since the low Friday night is forecasted at 33 degrees.

You should be able to blow into the bottom port and the air should come out the side port. If you can't blow thru the unit then it could be the problem and water may not get to it with the back pressure from not opening up. JMO.