I KNOW, STARTED OFF WITH HOT WATER RUNNING COLD THEN HOT ALTERNATE, SO CHANGED CHEAPEST FIRST, NTC'S, TO NO EFFECT, THEN SUSPECTED DIVERTER VALVE, SAME THING NO DIFFERENCE, AT THIS TIME NOTICED NUTS WERE LOOSE ON HEAT EX BURNER, AND WHEN I DROPPED THE AIR SUCTION DOWN IT HAD BEEN MELTED WHERE...