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Old 04-08-2015, 04:14 PM   #21
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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.
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Old 04-08-2015, 06:29 PM   #22
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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.


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Old 04-08-2015, 06:38 PM   #23
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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.
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Old 04-08-2015, 07:00 PM   #24
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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...
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Old 04-08-2015, 07:41 PM   #25
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... 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.
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Old 04-08-2015, 07:45 PM   #26
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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.
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Old 04-08-2015, 08:01 PM   #27
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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.
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Old 04-08-2015, 08:05 PM   #28
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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.
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Old 04-08-2015, 08:08 PM   #29
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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...
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Old 04-08-2015, 10:43 PM   #30
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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.
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