When selecting a water heater, there are a few things to take into consideration. You can choose between gas or electric, tank or tankless. The capacity of the tank, which ranges from 20 to 80 gallons, is determined by the size of the residence or building and the quantity of water used during peak hours.Residential water heaters typically last 10 to 15 years. Tankless water heaters are the most used type. Compared to tankless water heaters, regular tank water heaters are less expensive and require less maintenance. On the other hand, unfortunately they consume more energy. If the stored hot water is not used, it gets cold and needs to be reheated again. Instantaneous or on-demand water heaters are other names for tankless water heaters. It takes up less room since, as the name suggests, there is no tank. Energy costs are reduced by heating the water just when needed with a coil system. The initial cost of tankless gas and electric water heaters is higher, and you might need to replace your electrical system.