I'm working on a bathroom faucet that has been dripping. I turned off both shut-off valves (one to the hot and one to the cold). However, I also noticed a yellow lever on a pipe that feeds into the cold water supply pipe. In other words, three pipes come from the bottom of the sink cabinet (the drain pipe exits through the side of the cabinet), two of them combine before they go to the cold water side. One of those pipes has the usual shut-off valve but the other one has a yellow lever. It looks like the main shut-off valve near my water heater. What is this yellow lever for? Thanks for your help!
We can not tell you where it goes or what it is for specifically.
We can tell you what it is, It is a 1/4 turn valve, with it turned parallel to the pipe it is open and with it perpendicular to the pipe it is in the closed position.
My guess is it is a cold water feed to another fixture ( hopefully, and not just open ended.) You say it was in the off position before you did anything,
Is there a fixture elsewhere that does not function?
Do you have access to the plumbing below the bathroom ?
Of the two cold water lines i would think the left is the supply line and the tee off to the right is sending water elsewhere. I.E. Turning the clear plastic valve to the faucet off does not stop water from going to the yellow 1/4 turn valve via the tee, verified by the fact that you get water from the faucet when the yellow valve is closed and the clear plastic valve is open. Turn both valves to the closed position and then open the cold water only on the faucet,( no water should be coming out ) next open the clear plastic valve ( leave the yellow valve closed ) and if the water starts flowing from the faucet then the left line is supply line to the faucet.
Further investigation will be needed to determine what the yellow 1/4 turn valve is supposed to supply water to.
A hot water re-circulation loop is a loop within the hot water plumbing.