Tankless water heating is a that has boomed lately. Unlimited energy-saving is the most often mentioned in Tankless water heating industry, and a smaller footprint often mentioned.
Storage type water heating has become the standard of the United States, but recently have started Tankless water heating impact. Most people are familiar with storage (tank type) water heating, where you need it. Water can be heated with a gas flame, an electric heating element or other means.
Or storage tank type heaters have potential problems, the first is their use compared to a tankless heater standby, and the second, you could run out of hot water that you have ready. Tankless also has some disadvantages. For one thing tankless water heaters have a flow switch in the water line that turns on when they flow detected. Usually the flow around ½ gallons per minute or more. This pretty much eliminates access to low flows for anything.
If your primary concern or goal is to have a limited amount of hot water and you can live with a few shortcomings, the tankless unit is for you, if not, you may want to stick with the old-fashioned heating, good water storage type.