Plumbing Help

[Tomzspot]

Hey all!

We have a 2015 3402RL that has a mysterious white plumbing line that "caps" off under the bedroom sink. The cap seems to be some kind of pressure relief valve black in color? So, besides the normal red and blue lines this one is white. Cant see where it goes because it is too cold in Columbus Ohio to leave my pass through open that long! Anyway, the cap has started leaking under the sink (It is not the connection but the cap itself). If it is a pressure relief and is suppose to leak normally, why put under the bedroom sink?

Anyone experienced this? Help?

[hunts800]

That is the black tank flush line, and the fitting where the lines meet is a back flow preventer. It is not unusual for that back flow valve to leak. What is odd is that there should be no water pressure in that line unless you are flushing your black water tank.

[sapest]

Water is in the supply side and is freezing ?
Just a thought.
-Steve

[Tomzspot]

Under the sink? I could think of a thousand places to put it.

[mlh]

Under the sink is where most are and where mine WAS until it started leaking.
Lynwood.

[BB_TX]

You speak of "line" and "it" as singular. But the antisiphon valve mentioned above should have two lines, one going into it from the flush connection and a second one from the valve to the black tank. If the "cap" only has one line then it is either not the antisiphon valve, or someone forgot to connect a line. In any event, even a bad black tank antisiphon valve should not leak unless you were doing a black tank flush.

Can you post a picture of the "cap"?

[DQDick]

Actually it can leak when not flushing as it slowly lets water out that is in the tubing above it. Since the Tomzspot says he doesn't know where it goes I assume there are an entrance and an exit. White pipe, black valve, under sink it must be the backflow preventer. Many of us have taken this out and use an external one now, others have gotten a better quality one and replaced the OEM one. If you want to know what I use externally just email me.

[Dmcgrew]

Have the same thing under my sink, replaced it with a higher quality brass valve after reading the problems everyone is having with the oem valve.

[Jimmer]

I did the same thing, replaced it with a brass one from Amazon. Works great.

[grumpylane]

does anyone have a part number for the new brass one they purchased and if they had to change the fittings to get it to work