Once a heat exchanger has been selected, the rating engineer should ask if there is any reason why the equipment chosen is not a good choice for the application. In the first part of this chapter, two examples illustrate the point. Each cites conditions affecting the selection that often favor making another choice. Both cases emphasize that attention to detail minimizes the potential for costly errors. While adding a requirement may change the recommendation for a large exchanger, it is equally true of smaller units. These too must be lifted and maneuvered when space is limited. Space considerations are emphasized, but other factors affect a selection as well. In the final analysis, conditions that can limit a selection should be in the specifications.