AQUAH Outdoor Liquid Propane Gas Tankless Water Heater 10 L / 2.7 GPM AQUAH liquide propane gas tankless water heater, 2.7 gal (10 L)/min or 159 gal/hr; Automatic electrical pulse ignition with no standing pilot, operated by 2 D Batteries or 120V AC 85% thermal efficiency, 20,000 Watt / 68,242 Btu/h thermal input 45 dgrees temperature rise at the flow rate of 2.7 gllons per minute (GPM) Stainless steel rain cap for outdoor use, free 1/2" BSP (Metric) to 1/2" NPT adapters for gas/water fittings ($45 value).