Jabsco Y-Valve Confusion

Jun 14, 2025
70
Hunter 1981 30 Chesapeake
I’m trying to confirm if this is routed to the holding tank (red arrow). The valve says “Open,” “Open,” and “Flow” instead of the usual arrows. Flow seems to be connected to the piping to the waste holding tank.

Why is only one port labeled “Flow”? Anyone familiar with this style of Jabsco marine head Y-valve?
 

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May 1, 2011
4,999
Pearson 37 Lusby MD
On my boat with a similar Y valve, the "flow" is in the hose where the handle parallel to. So, if you can rotate the handle to where the red arrow is in your photo, the "flow" should be in that hose.
 
Jun 14, 2025
70
Hunter 1981 30 Chesapeake
Thanks! Just to confirm: the flow goes through the hose the handle points toward, right? So if I turn the handle (long black part) to the red arrow hose, even if “Flow” disappears from view, that’s still the active path?

Also, is it safe to rotate the handle 360 degrees if needed, or could that damage something?

The hose labeled “Flow” seems to go to the holding tank — if I move the handle off it, does that cut it off? Still confused about the “Open/Open/Flow” labeling — does the label matter, or just the handle position?

Appreciate the help!
 
May 1, 2011
4,999
Pearson 37 Lusby MD
Thanks! Just to confirm: the flow goes through the hose the handle points toward, right? So if I turn the handle (long black part) to the red arrow hose, even if “Flow” disappears from view, that’s still the active path?
That's the way it works on my boat, but I don't recall what the labeling on my Y valve is.
Also, is it safe to rotate the handle 360 degrees if needed, or could that damage something?
My handle won't rotate 360 degrees, so don't have a good answer for you. I don't believe mine will rotate like that.
The hose labeled “Flow” seems to go to the holding tank — if I move the handle off it, does that cut it off? Still confused about the “Open/Open/Flow” labeling — does the label matter, or just the handle position?
Assuming your set up is similar to mine, one position goes to the holding tank and the other goes overboard. If there is an Open label under the handle in your photo, then I would surmise that the Flow label is from the head, and one Open directs the effluent to the holding tank, and the other overboard. So the flow would be in the opposite direction of the red arrow you drew. Can you rotate the handle to the other Open position?