Hot water heater not making hot water. Diagnose and find water heater is over 8 years old and should be replaced. 8 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 Navien tankless water heater with new pan and test for functionality. Recommend Gemline water softener to protect new water heater from hard water damage.