AQUAH NG (Natural Gas) tankless water Heater, 4.23 gal (16 L)/min or 254 gal/hr, automatic electrical pulse ignition with no standing pilot, no electric Hookup necessary, operated by 2 D batteries or by 110 V AC as alternative, free AC Adapter, IC water control device, thermal efficiency >=85%, 32,000 Watt / 109,260 Btu/h thermal input, 45* temperature rise at 4.23 gpm flow rate, 25 to 110 water pressure for operation, 2000 Pa (0.29psi) gas pressure, 1/2" water inlet/Outlet, 1/2" gas inlet, Winter/Summer control; Min/Max Water/Gas flow adjustment, dimensions: 27" H x 16 1/2" W x 8" D, net weight: 30.20 lb, requires 5" double wall type B vent pipes (not included).