An existing chiller with a capacity of 800 kW and with an average seasonal COP of 3.5 is to be replaced by a new chiller with the same capacity but with an average seasonal COP of 4.5 . Determine the simple payback period of the chiller replacement if the cost of electricity is $0.07/kWh and the cost differential of the new chiller is $15,000. Assume that the number of equivalent full-load hours for the chiller is 1,000 per year both before and after the replacement.