Takagi tankless hot water heaterTakagi tankless hot water heater. Tankless hot water heaters may also becalled instantaneous or instant-on hot water heaters. They are powerfulhot water heaters and also heat the water instantly mainly because it flows through the product. These heaters have flow sensors and acquire activated when water flows through it. The Takagi T-KJr 2-IN-NG Indoor Tankless Hot Water Heater will be the smallest device manufactured byTakagi.