Open the drain valve after unscrewing the water supply line and allow sufficient time for the water to drain out of the heater into the basin.
Cleaning gas water heater.
Unthread the nut to detach the burner supply tube from the gas or control valve.
Take a water hose and attach it to the drain valve.
If there is a thick layer of dust or dirt on your hot water heater use a shop vac to take off as much dust as possible.
Before you begin be sure to unplug the water heater s power cord and shut off the gas supply.
Turn off the hot water heater.
If necessary unthread any mounting screws and remove the burner access cover.
Open the drain valve at the bottom of the hot water heater tank.
Open a hot water tap close.
Remove the temperature pressure release valve and screw in the vacuum adapter.
Next unthread the nuts or screws securing the burner plate itself.
Wipe the hot water heater down with a dry cloth to get rid of as much.
How to clean a hot water heater.
Attach the shop vacuum hose and fire up the vacuum.
Shut off the gas or electricity to the water heater and open a hot water faucet and let it run full blast for about 10 minutes to reduce the water temperature in the tank.
Once the water has drained close the valve.