This is strange...I replaced the shower valve with an anti-scald system...simple. Cut the old pipe, put the new valve in and sweat the joints. Works great but when the cloths washer is turned on water leaks out of the shower. The shower is on the second floor, washing machine oin the first floor. Also, when this happens the pipes SING. The singing will stop if I open another faucet but resumes when I turn the faucet off. For the life of me I can't figure out what happened. Any help?