Why do IT Equipment Air Inlet Temperatures deviate from Supply Air Node Temperatures ?

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From the Input Output Reference:

Air Inlet Connection Type Specifies the type of connection between the zone and the ITE air inlet node. The choices are: AdjustedSupply = This option is used to apply a recirculation adjustment to the ITE inlet conditions. If this option is specified, then the Supply Air Node Name is required and the air inlet temperature to the ITE will be the current supply air node temperature adjusted by the current recirculation fraction.

ITE Air Inlet Dry-Bulb Temperature is the temperature entering the equipment after adjusting for recirculation, so this will not be the same as the supply inlet node temperature unless the recirculation fraction is set to zero.

IT equipment is simulated at the zone time step (same as other internal gains such lights, people, etc)he, so the ITE output variables are all reported at the zone time step.