A few weeks ago we noticed on the garden faucet (just outside the kitchen)
there was a device that was beginning to leak a small spray of water. I
removed it and took it to osh and was told it was a backflow preventer (or
something close to that). They had them so I replaced it. Now when we use
the kitchen faucet when we turn it off the pipes make a sighing sound. If I
close the garden faucet then the pipes dont do that. But I like to have the
faucet on. Did I not install the backflow preventer correctly? Didnt see
any instructions.

A few weeks ago we noticed on the garden faucet (just outside the kitchen)
there was a device that was beginning to leak a small spray of water. I
removed it and took it to osh and was told it was a backflow preventer (or
something close to that). They had them so I replaced it. Now when we use
the kitchen faucet when we turn it off the pipes make a sighing sound. If I
close the garden faucet then the pipes dont do that. But I like to have the
faucet on. Did I not install the backflow preventer correctly? Didnt see
any instructions.


If water comes out of the garden hose when you want it to, then
the backflow valve is not installed backwards.
My guess is that the shockwave when you turn the kitchen
faucet off is enough to drive a little extra water into the
hose (Which, being flexible, swells) and this extra pressure
is enough to drive water either back through the backflow valve,
(in which case, it's defective) or out through whatever is on
the end of your hose.