Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
A return fan should be placed on the node before the AirLoopHVAC:OutdoorAirSystem, as you described. This fan will show up as the first component listed in the branch that describes the air loop's "Primary Air System", which is the 'supply side' of the air loop:
A relief fan will be placed on the relief air node of the outdoor air system. In the IDF, the fan will be listed as a component in the AirLoopHVAC:OutdoorAirSystem:EquipmentList object, not on the air loop's supply branch:
