An Air System's supply fan can be located in a Blow-through or Draw-through position.
The Blow-through position locates the fan upstream (before) the heating and cooling coils. This position will result in heat from the fan being added to the air stream before it is conditioned by the coils (coils are sized including heat gain of fan).
The Draw-through position locates the fan downstream (after) the heating and cooling coils. This position results in heat from the fan entering the air stream after is is conditioned by the coils (unit LAT is higher than coil LAT).
An Air System's Relief fan can be located in Return or Exhaust position.
The Return position locates the fan in the return air path of the system. This results in a fan sized for the entire return air flow rate upstream (before) of the mixing box. If the fan motor is located in the air stream, the fan heat will be added to the return air temperature seen by the system.
The Exhaust position locates the fan in the exhaust air path of the system. This results in a fan sized for only the exhaust portion of the air flow downstream of the mixing box.
By default both fan motors are located within the air stream of the system. A future release will enable customizing the location of the motor based on the design intent.