Replacing Check value/vaccum breaker plastic on CamperI

[ngranneman]

So I need to replace my plastic check valve/vacuum breaker (plastic contstruction) on camper because it leaks once I turn off the water cleaning the black tank with the flush line. From looking online this is a common thing and the plastic ones seem to have a high failure rate and they are like 40 bucks on amazon. Any recs on replacement ones that are less likely to fail? I came across the following one on some forums/reviews however it doesn't have a the check valve feature so don't know if adequate for what I am replacing?

https://www.amazon.com/Cash-Acme-17383-0000-Anti-Siphon-Breaker/dp/B000MNLNF6/ref=sr_1_13?ie=UTF8&qid=1517430224&sr=8-13&keywords=Vacuum+breaker

 

[grashley]

That should do the job.

 

[RVRAC]

Mine started to leak.  I called Coachmen and they sent me a replacement.

 

[lynnmor]

They leak by design and nearly all are installed wrong, see: http://www.bandbmolders.com/wp-content/uploads/2017/03/BBCatalog-WaterSection.pdf

The brass one mentioned earlier does not have a check valve, so one should be added.  I just use only a check valve and always disconnect the hose when not in use.

 

[ngranneman]

What is the check valve component for and the vacuum break component for?

They leak by design and nearly all are installed wrong, see: http://www.bandbmolders.com/wp-content/uploads/2017/03/BBCatalog-WaterSection.pdf

The brass one mentioned earlier does not have a check valve, so one should be added.  I just use only a check valve and always disconnect the hose when not in use.

 

[lynnmor]

What is the check valve component for and the vacuum break component for?

When the black tank hose is connected to a city water hydrant, it is there to prevent back-flow to that hydrant.  In order to have back-flow, all of the following needs to happen:

The campground water systems needs to fail.
The water pressure needs to drop below zero.
Any back-flow device supplied by the campground needs to fail.
The water spigot needs to be open.
The check valve in your RV needs to fail.
The vacuum breaker needs to fail.
The level of the tank contents needs to be as high as the flusher.

I concluded that the dangers presented by an open vent under my kitchen sink, water leaking into an electrical box and doing damage to the structure, was enough reasons to eliminate the stupid thing and just use common sense when flushing the tank.

 

[ngranneman]

Do you know what the flood rim of the highest fixture connected to the waste holding tank is referring to?

must be 6? above flood
rim of the highest fixture connected
to the wasteholding tank.

What is the check valve component for and the vacuum break component for?

 

[Old_Crow]

Do you know what the flood rim of the highest fixture connected to the waste holding tank is referring to?

must be 6? above flood
rim of the highest fixture connected
to the wasteholding tank.

I would take that to mean that the breaker has to be 6" higher than the level the water will reach in the highest sink, tub, toilet, or washer/dryer before it starts pouring on the floor of the coach.

 

[RVRAC]

I think this needs to be clarified.  The vacuum breaker connected to the blank tank has no connection to the sinks or shower.  It is connected only to the outside connection of the black tank flush.  There are some units that have a second vaccum breaker connected to the grey tank.  This one is connected to the sinks and shower.  Two different pieces, the initial question was about the black tank one.

 

[ngranneman]

What is the difference, though, between a check valve and a vaccum breaker or is it the same thing