Hot water heater making noises. Diagnose and find leaking gas control valve. 12 year old Rheem water heater. Recommend replacement Rheem tank water heater, or Navien tankless water heater. Average water heater life span is 8-12 years old. Install new Rheem tank water heater with new pan and test for functionality. Recommend Gemline water softener to protect new water heater from hard water damage.