In household and commercial usage, most water heaters are of the storage tank type. They are also called storage water heaters or “hot water heaters.”
These consist of tanks in which a given amount of water is kept continuously hot and ready for use. Typical sizes for household use are 30 to 75 gallons. There are several types of water heaters on the market today. The most popular are gas water heaters, electric water heaters, and propane water heaters, and other energy sources. You will commonly find that a natural gas water heater is being used in your home since it is currently the cheapest energy source to run.
There is another type of water heater that has recently been introduced to the market called a tankless water heater. This unit provides instant hot water and like the name suggests, there’s no water tank so it’s smaller in size and will fit into more places.