A fuel gas consisting of 94 mol-% methane and 6 mol-% nitrogen is burned with 35% excess air in a continuous water heater. Both fuel gas and air enter dry at 77((F), Water is heated at a rate of 75(lbm)(s)-1 from 77 ((F) to 203((F). The flue gases leave the heater at 410((F). Of the entering methane, 70% bums to carbon dioxide and 30% bums to carbon monoxide. What volumetric flow rate of fuel gas is required if there are no heat losses to the surroundings?