A boiler has an annual fuel oil No. 2 consumption of 325,000 gallons. The cost of fuel is $1.50/gallon. A combustion efficiency test done on the boiler indicated that the stack temperature is 650°F and the CO2 content is 11 percent.

a. Determine the excess combustion air and the boiler efficiency.

b. If the fuel-air ratio is adjusted so that the boiler efficiency is increased to 84 percent, determine the payback period, the net present worth, and the rate of return (d = 5 percent over ten years) of installing a full metering kit with O2 trim control that costs $45,000. Comment on the cost-effectiveness of the kit.