What do the numbers on a tire mean? The DOT number appears on the sidewall of all tires intended for sales in the U.S., and designates the location of manufacture, the week and year of production, and the specific tire.
Water heater anode rod or sacrificial anode is the important component part with only one purpose; to protect metal tank from corrosion. Use this article to learn how to replace the anode, installation tips, how it works, about different types and when to use each one.
If you have your power out for some days and still have real hot water, chances are you have the natural draft water heater that does not require electricity for ignition. Good luck. By disconnect power they mean  interrupt the power supply to the waterheater which you can do simply by turning off the breaker to the water heater.