Valve

[Don and Kathy DuCharme]

Help!  Developed a water leak under vanity in toilet room of 07 Contessa.  The leak is a plastic backflow preventer connected to what appears to be a pressure/temp valve.  There is a blue water line going in and a red comming out.  These lines are not attached to the lavatory faucet or the Hydro hot unit.  Anyone know what these lines are connected to?  The valve appears to be a relief valve of some sort, but probably is not funtional.  Any help will be appreciated.
Thanks

[Joel Ashley]

This may be your culprit, Don -

http://www.cashacme.com/_images/pdf_downloads/products/backflow/v101/V101_Spec.pdf

Mine is model V101.  The flow is from the blue tube to the red one.  I wish I could help beyond identifying the device, as I don't know the precise engineering involved, but likely someone on the Forum does.  My guess is it is between the city water fill and the water tank, but I'm not sure why you'd have an ongoing leak there unless the city water was on tank fill mode constantly, since otherwise the valve wouldn't be subject to water pressure.  The tank fill valve is in the off position at the manifold isn't it?  But if not you'd have noticed the overflow discharge.  :-/

Joel

[Tim Bentley Co-Admin]

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[Joel Weiss]

That appears to be a backflow prevention device (an air gap) which probably is designed to make sure that water in the fresh tank can't siphon back down the input hose.

[Brad Burgess]

This back flow preventer pictured was on my Sanicon tank flush circuit.  If that's what it is, I don't know why it would leak constantly.

Brad Burgess

[Joel Weiss]

Actually, having it on a tank flush system would make sense.  Even though your Sanicon is more complex than the tank flushing system on our coach, I assume the same basics apply.  When I disconnect the hose from the flushing connector only clean water comes out because there is a vacuum breaker in the system which prevents nasty stuff from coming back out.

If you've done something like keep the flush-out hose connected but turned off you run the risk of a slow "trickle" of water continuing to flow through the hose (maybe because the shutoff valve doesn't completely turn off).  A vacuum breaker doesn't work well with a trickle of water, it needs a steady flow in order to make sure water doesn't leak out through the gap.  This could be what is happening in your case.  I normally never leave the flush-out hose connected when not in use to prevent accidental (disastrous) consequences of it being turned on by mistake.

[Brad Burgess]

Hello All

OOPS!  In my previous triple post I should have said San-T-Flush, NOT Sanicon.  This vacuum break was on the black tank flush circuit and was located behind my washing machine.  If you go to http://www.rvproductsnow.com/SwanRvProducts/Product%20Categorie%20Pages/Flushing%20Systems.php you will see how it fits in the tank flush system.  Sorry for the mix up.

Brad Burgess

[Joel Weiss]

Ok, so it's the same as what we have.  So the question is do you have a hose connected on the outside when you are experiencing this leak?

[Don and Kathy DuCharme]

Thanks everyone!  The leak was sporadic, but I did not make the association with using the San-T-Flush. That, in fact, is when the leak occurs (confirmed today).  The leak is because the plastic backflow valve connected to the brass valve is broken where it attaches to the red water line.  Now, thanks to all, I know that I can temporarily fix the problem by capping the 2 water lines until I get the replacement valve.  Thanks again.
Don

[Brad Burgess]

Hello All
Thanks Joel.  I actually replaced the vacuum breaker with a brass back flow preventer valve.  When the vacuum break fails it also allows black tank odors into the coach.  As soon as I can figure out how to correctly size photos for posting here I will post a shot of the valve replacement.

Brad Burgess

[Joel Ashley]

I guess I'm still unsure why there is a vacuum breaker on that San-T-Flush line.  The tank vents via the roof port, and there is a backflow device immediately downstream of the breaker anyway (the part that cracked on Don's), to keep any tank fluid from going back into any potable water source via the hose attached at the water bay fixture.  Perhaps the breaker prevents water from draining back into the bay after you remove the hose, as Joel W. mentioned?  If so, might it be a good idea to bleed or blow out that line when winterizing?  Otherwise the stated intent on the product website is basically the same as the backflow device's, so is it necessary?

Joel

[Brad Burgess]

Hi Joel

On the two coaches that I eliminated the vacuum break on (03 and 06 Montereys) there was no back flow preventer valve in the lines in addition to the vacuum break, either at the hookup in the wet bay or near the vacuum break.  I am surprised that both devices were found in the subject coach.

Brad Burgess

[Joel Ashley]

Okay, perhaps I made an assumption here.  I figured the white plastic between the breaker and the outfeed elbow was the backflow device Don referred to;  mine is turned so I can't read the characters on it.  Perhaps it is merely a connector, but it does have a flow arrow on it.  Feel free to chime in here, Don, since you have to replace the leaky white device, whatever it is.

Joel

[Brad Burgess]

Hello All

The attached photos show where I removed the vacuum breaker and installed a brass check valve in its place.  They also show the plumbing that I added so that I can fill the P-trap for the washing machine without having to run the machine itself.

Brad Burgess

[Don and Kathy DuCharme]

Joel,  the leaky white plastic device is indeed a backflow preventer or check valve if preferred. It is a spring loaded valve that will prvent backflow from the red line to the blue line. As soon as I find the replacement part I will post it on this thread.  Probably will be a few days since we are on our way to attend the FMCA G.L.A.S.S rally at Berrien Springs Michigan.