Turn off the water supply, power, and fuel source to the water heater
Drain the old water heater if replacing one
Position the water heater in its final location
Install a cold water shutoff valve on the incoming supply line
Connect the cold water inlet to the water heater
Connect the hot water outlet to the home’s hot water line
Install dielectric unions or approved connectors if required
Add a temperature and pressure relief valve if not already installed
Route the T&P discharge pipe to an approved termination point
Install an expansion tank if required by code or system type
Use approved pipe materials and fittings for the local code
Seal threaded joints with approved pipe thread sealant or tape
Support and secure all piping properly
Check that all connections are tight
Open the cold water supply and fill the tank
Open a hot water faucet to purge air from the system
Inspect all joints for leaks
Restore power or relight the gas burner only after the tank is full
Verify proper operation and temperature settings