Instruction manual

70 McQuay OM 920
Operator’s Guide
Determining Outside Air Damper Position
OAD/Econo Cap is a status only item which indicates the current outdoor air damper or
economizer valve position. The current OAD/Econo Cap can be view via the following path:
Standard Menus/System/OAD/Econo Cap.
Determining Emergency Mode
Emergency Mode is an adjustable only item which is normally used by a network system to
shutdown the unit in an emergency situation. The parameter is adjustable via the following
path: Standard Menu/System/Emerg Mode.
Determining Application Mode
The unit heating and cooling can be set up for automatic heat/cool, heat only, cool only or fan
only operation based on a network signal by setting the Control Mode parameter to “Auto.”
With the Control Mode parameters set to “Auto,” the heat/cool, cool only, heat only, and fan
only decision is determined by the Net App Mode. The Net App Mode is set by a network
signal. The following sections describe the five available Net App Mode selections.
Note – The Net App Mode has no effect on the unit operation unless the Control Mode parameter
is set to “Auto.”
Off
When the Net App Mode is set to “Off,” the Unit Status is “Off Net” and the unit is completely
disabled, including unoccupied heating (night set back) and unoccupied cooling (night set up)
operation.
Heat Only
When the Net App Mode is set to “Heat Only,” heating operation is allowed to operate as
required to maintain the heating set points. Cooling operation is disabled (Cooling Status is
“Off Net”).
Cool Only
When the Net App Mode is set to “Cool Only,” cooling operation is allowed to operate as
required to maintain the cooling set points. Heating operation is disabled (Heating Status is
“Off Net”).
Fan Only
When the Net App Mode is set to “Fan Only,” the fans are allowed to operate but cooling and
heating operation is disabled (Cooling Status and Heating Status are “Off Net”).
Auto
When the Net App Mode is set to “Auto” heating and cooling operation are allowed to operate
as required to maintain the heating and cooling set points.