AQUAH Indoor Natual Gas Tankless Water Heater 12L / 3.2 GPM AQUAH natural gas tankless water heater, 3.2 gal (12 L)/min or 192 gal/hr Automatic electrical pulse ignition with no standing pilot, operated by 2 D Batteries or 120V AC 85% thermal efficiency, 24,000 Watt / 81,946 Btu/h thermal input 45 dgrees temperature rise at the flow rate of 3.2 gllons per minute (GPM) Free 1/2" BSP (Metric) to 1/2" NPT adapters for gas/water fittings ($45 value).