Trane model numbers for RTUs are used to help define the operation of a particular unit as well as a means of identification. This allows people who service, install or own Trane RTUs to identify how a particular unit operates.
Trane model numbers for RTUs are broken down into a series of alpha-numeric symbols that are usually 25 digits long. Where a symbol is in the model number determines what it identifies and the specific operating parameter it defines. For example, a model number's tenth unit indicates a unit's heating capacity, where "L" stands for low and "H" stands for high. Explanations of each number and symbol can be found online on Trane's website or in the unit's manual.