The purpose of this paper is to provide a broader understandingof Reliability Engineering and how it can be successfullyused as a tool for designing better mechanical coolingsystems. We will also point out a few of the pitfalls when usingreliability modeling to be avoided along the way. The use ofprobabilistic methods of predicting failure developed in ReliabilityEngineering has greatly assisted the design of reliableelectrical power distribution systems for data centers. Thesesame proven techniques have been applied to the mechanicalcooling systems. A review of the metrics of Reliability Engineeringwill also be included.