AQUAH liquid propane gas tankless water Heater, 2.7 gal (10 L)/min or 159 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%, 20,000 Watt / 68,242 Btu/h thermal input, 45* temperature rise at 2.7 gpm flow rate, 25 to 110 psi water pressure for operation, 2800 Pa (0.41 psi) gas pressure, 1/2" water inlet/Outlet, 1/2" gas inlet, Winter/Summer control; Min/Max Water/Gas flow adjustment, dimensions: 24" H x 13 3/4" W x 7" D, net weight: 24 lb, requires 4" double wall type B vent pipes (not included).