ICC Commercial Mechanical Practice Exam

The correct positioning of a secondary drain pan is to install it below the primary drain pan. This arrangement is crucial for ensuring that any overflow or leakage from the primary drain pan is effectively captured by the secondary pan, thereby preventing water from causing damage to the surrounding area.

Installing the secondary drain pan below the primary pan allows it to act as a safeguard, particularly in environments where the risk of condensate overflow exists, such as in HVAC systems. The secondary pan is designed to provide an additional level of protection, so if the primary system fails or becomes clogged, the secondary pan will collect the excess water, thus mitigating any potential leaks or damages.

The other positioning options would not fulfill the intended protective function of the secondary pan. If it were installed above or next to the primary pan, any overflow would simply fall onto the ground or the surfaces below, leading to water damage instead of capture. The absence of positioning requirements would undermine the design intent of having a secondary safety feature to manage condensate issues effectively.