AQUAH PREMIUM DIRECT VENT NATURAL GAS TANKLESS WATER HEATER 3.7 GPM Brand New AQUAH Premium direct vent natural gas tankless water heater 3.7 GPM with 45 temperature rise, Thermal Output: 28,000 Watt /95,600 Btu/h; Compact, highly efficient and ideal for indoor use with thermal efficiency of &gt;=88%. Constant water temperature regulated by thermistor regardless of fluctuations of water/gas flow. Runs automatically with no need for user intervention.