A gas water heater is a water heating system that incorporates a gas burner that heats up the water running through it. A gas water typically has two water pipes, one each for hot and cold water, as well as a chimney running up its middle portion.
Water heaters are generally used to heat up water before it's used at homes and buildings. Water heated inside a water heater can be used for showers, baths or dishwashers. Aside from using gas, water heaters can also use electricity as a power source. Electric water heaters typically do not have a chimney, but instead use two heating elements that are placed in its interior.