OUR HOUSE IS 5 YEARS OLD AND EVERY TIME WE TURN ON THE HOT WATER THERE IS A VERY LOUD HOWLING FROM THE AIRING CUPBOARD AND THROUGH THE PIPES. IT SOMETIMES STOPS IF WE TURN ON THE COLD TAP. AT THE MOMENT IT SEEMS THAT IF WE RUN OUR BATHROOM TAPS FOR ABOUT 1 MINUTE, IN SEQUENCE COLD HOT, THEN OFF WITH HOT COLD, THEN RUN THE SHOWER OR BATH, NO HOWLING. IT'S DRIVING US MAD! CAN ANYONE HELP? (WE ARE DIY USELESS!)