Should the evaporator coil be positioned upstream of the furnace’s heat exchanger?

The correct answer indicates that the evaporator coil should not be positioned upstream of the furnace's heat exchanger. The primary role of the evaporator coil in an HVAC system is to absorb heat from the air, cooling it before it circulates throughout the home.

When the evaporator coil is positioned downstream of the furnace's heat exchanger, the heat exchanger can preheat the air before it passes through the evaporator coil. This configuration enhances the overall efficiency of the heating and cooling process because the heated air assists in maintaining an optimal temperature in the space, while also preventing potential damage to the evaporator by avoiding direct exposure to excessive heat.

If the evaporator coil were positioned upstream, it would end up cooling the air that is then heated by the furnace, which is counterproductive. This arrangement could lead to poor system performance, reduced efficiency, and increased wear on components as they work against each other. Therefore, proper placement of the evaporator coil is critical for the efficiency and longevity of an HVAC system.