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 $TE285. 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)