Close the valve on the gas line leading to the Whirlpool water heater. Wait at least half an hour for the unit to cool before servicing.
Remove the screws holding the access door in place on the bottom front of the water heater. Lift the door out of the way.
Remove the hex head screw connected to the internal valve. Pull the thermocouple straight down to disconnect it.
Unplug the wire connectors leading to the thermocouple. Set the old thermocouple aside.
Plug the wire connectors into the new thermocouple. Position the thermocouple where the old part was. Push the thermocouple straight up to hook it into the burner assembly.
Replace the hex head screw connecting the internal valve.
Replace the access door. Install the screws that hold it in place. Open the gas valve leading to the water heater.