Adjust the temperature DOWN. This will keep the flame from coming on while draining your tank.
Locate the cold water line and shut-off valve.
How to locate the right valve.
Most water heaters have 1 valve; this will be the cold water supply. If you have 2 valves, just feel the lines- the cold line will be the supply.
Hook up your hose to the bottom drain valve. Sometimes this can be a little leaky; have a bucket and a towel handy!
Make sure to drain into the street gutter. NOT YOUR GRASS- the sediment will "burn" your lawn.
Open a hot water faucet inside the house. This relieves the vacuum on the water heater. Locate a faucet that has 2 handles (usually a bathroom sink), faucets with single handles do not work.
Leave your hot water faucet open during the whole process. When you fill your tank back up you should hear "air/bubbles", this is the tank filling up and pushing air out.
Some final notes.
Turn your temperature back up!
Important Notes: 1. You may feel your water temperature is a lot hotter; this is normal now that your tank is working better and efficiently. If its too hot, adjust the temperature down.
Important Notes: 2. If you have a plastic valve where you hook up your hose, pick up a "gate valve (1) and 3" "brass nipple" from your local hardware store BEFORE starting this process.
When you are done draining your water heater, install the new brass nipple and gate valve assembly.
And, feel free to ask me questions before starting the process. I WILL respond!