Hot water heater not heating. Diagnose and find water heater is over 8 years old and should be replaced. 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 water leak protection device (FloodStop) to prevent future damage from water leaks.