I just installed a new water heater. I wanted to replace the shut off valve for the cold water inlet, and there is a smaller tube running next to the 3/4 copper line. Can anyone tell me what the smaller tube is and what it is for? Thanks, Dan

It is probably return for hot water circulating pump.

Post pic using "Go advanced"

Post pic using "Go advanced"

Sorry guys, here are a couple of pics. The cold water is on the right and in the second picture, the other tube is above the cold water line.

http://i142.photobucket.com/albums/r95/dano540/IMG_0244.jpg

http://i142.photobucket.com/albums/r95/dano540/IMG_0245.jpg

It is Ground Copper Wire from main electrical service panel.

Called a water bond.
Very good guys!

Thanks for the info guys. I appreciate it.

Called a water bond.
Very good guys!

One more question. I wanted to put a new shut off valve there. Any concerns or things to worry about. Can I temporarily move it until the new valve is in place?

Nothing to worry about. Unscrew the clamp, install new valve, and reinstall the clamp. No need to even loosen the copper wire itself.

Nothing to worry about. Unscrew the clamp, install new valve, and reinstall the clamp. No need to even loosen the copper wire itself.

Sweet. Thanks everyone.