Tankless water heaters are the type of heaters which directly heats the water when the water passes through it. Tankless water heaters are also known as demand-type or instantaneous water heaters. Tankless water heater does not contain a tank for storage and heats the water with the support of heat exchanger coils. These water heaters are made up of sensors and copper heat exchanger coils. Meanwhile, it is considered as energy efficient as it only heats water when water is flowing through unit.