Whistling Duct Grilles
If you have a grille or register that hums or whistles, all you have to do is twist the fins slightly until the noise stops. Pliers will scratch and kink the delicate fins, so use a hinge with strips of tape applied to the inside. Then grab a fin between the hinge leaves and give it a twist. Twisting all the fins so they open a little wider will give the best results.
Fix for Noisy Pipes: Cushion the Pipe Hangers
Minimize the sound by pulling off the straps and inserting strips of felt or heavy fabric under the strap before reinstalling them. You may only have to fix the hot water supply line, because that’s the one that changes temperature the most. These are the 10 most common plumbing mistakes DIYers make at home.