AmeriHot Tankless Instant Hot Water Heater - Electric 18kw Energy Efficient - tankless heaters are 34% more energy efficient than conventional water heaters. Resource efficient  tankless hot water heaters heat only the water you need, when you need it. Space efficient  tankless hot water heaters take up less space than a traditional water heater. Time efficient - heats water in less time, and never any waiting for more hot water. Cost efficient  our tankless heaters are less in cost to a traditional water heater.