I have a couple of issues that may or may not be related. I have seen bits and pieces of similar issues, but not sure if they apply to mine. I had the cold water shut off to my kitchen sink for about 3 0r 4 weeks while I waited on the new single hot and cold valve. The pipes inside the walls starting vibrating shortly after I had cut off the cold water shut off valve in the kitchen. I finally got the part and replaced the faucet handle. My pipes continue to make the rumbling sounds, and turning on the water in one of the bathrooms or kitchen temporarily stops it. My water heater is a GE 80 gallon tank and it is about 5 or 6 yrs old. I thought maybe tripping the pressure relief valve would stop the vibrating, but it didn't, and now the pressure relief valve wont stop dripping unless I cut off the main. Is there a relation to theses two issues? I lifted the relief valve up an down several times thinking maybe it was sticking like I have read happens, but it did not fix it. Should I try tapping on the outside of that valve with a rubber mallet in case the plunger is just stuck or what do you recommend? Not that this is necessarily related, but I had just replaced a grey PVC elbow going to my outside spicket with a brass elbow right before I replaced the kitchen faucet valve. The water heater has never gave me any problem before this. I also turned down the temp on the water heater from the factory 125 deg setting probably down to 110 or so. It does not have a reading there.