Upon arrival water heater was off and valved off. Opened valves to fill the water heater and found that the pressure relief was the cause of the water leak. Once the water heater was full the pressure relief started dripping. Drained water from the system and removed the old pressure relief. Installed the new pressure relief and filled the system back up with water. Started and tested the system. While testing the water heater we found that the aquastat was not sensing the water temperature correctly. When the aquastat was set to 100 the unit would not turn off until the temperature of the water was 125-130. Recommend replacing the water heater instead of the aquastat due to the age of the tank.