In a reverse osmosis system, the water can be cooled using one of two systems: a single-pass heat exchanger or a closed-loop heat exchange system.
1. The single-pass system, good for 3 years, requires a small chiller costing $S=858 plus stainless steel tubing, fittings, etc.. costing $T=285. The cost of water, treatment charges, electricity, etc., will be $C=3.03 per hour.
2. The closed-loop system will have a useful life of 5 years, cost $P=4, 102 to buy. and will cost $X=1.23 per hour to operate.
The salvage values are negligible. The company's MARR is 10%.
What is the minimum number of hours per year that the cooling system must be used in order to justify purchase of the closed-loop system? (Round your answer to a whole number of hours - no decimal places)