Turn off power to the water heater at the breaker or shut off gas supply
Turn off the cold water supply valve to the heater
Open a hot water faucet to relieve pressure
Drain the tank using a hose attached to the drain valve
Disconnect the water lines
Disconnect the electrical wiring or gas line
Remove the old water heater
Place the new water heater in position
Connect the water lines
Connect the electrical wiring or gas line
Open the cold water supply and fill the tank
Bleed air from hot water faucets until water flows steadily
Check all connections for leaks
Restore power or relight the gas burner
Set the thermostat to the desired temperature
Test the water heater for proper operation