Instruction manual

McQuay OM 920 71
Operator’s Guide
Determining Occupancy Status
Occupancy is a status item which indicates whether the unit is in an occupied, unoccupied or
tenant override mode of operation. The current Occupancy status can be viewed via the
following path: Standard Menus/Occupancy/Occupancy. The following are descriptions of the
various “Occupancy” states.
Occ
The Occupancy parameter indicates “Occ” when the unit is in the occupied mode. In this
mode, the unit starts and runs continuously, cooling and heating as required to maintain the
occupied temperature set points. The unit is in the occupied mode if any of the following
conditions are true:
• The Occ Mode entry on the keypad is set to occupied
• The Occ Mode entry on the keypad is set to Auto, and a manual network occupancy
command is sent to the controller
• The Occ Mode entry on the keypad is set to Auto, a manual network occupancy command is
set to Auto, and any of the following is true:
• The External Start/Stop switch is closed
• A network schedule signal is set to Occupied or Standby
• The internal schedule function is in the Occupied condition
Unocc
The Occupancy parameter indicates “Unocc” when the unit is in the unoccupied mode. In this
mode, the unit remains off unless unoccupied operation becomes active. When unoccupied
operation is active the unit operates normally except that Minimum OA Position is set to zero.
See Unoccupied Operation below for information regarding when unoccupied operation is
activated.
TntOvrd
The Occupancy parameter indicates “TntOvrd” when the unit is in the tenant override mode.
In this mode, the unit starts and runs continuously, cooling and heating as required to maintain
the occupied temperature.
Tenant override operation is initiated when the Tenant Override Timer is greater than zero.
The Tenant Override Timer is set equal to the Local Tenant Override Time (Timer Settings
menu) if the unit is enabled and any of the following is true:
• The Space Temperature sensor is present and is shorted for less than 10 seconds. Nothing
happens if the button is pushed for more than 10 seconds but less than the time required to
initiate a shorted sensor alarm (30 seconds). Subsequent presses on the button resets the
Tenant Override Timer to the Local Tenant Override Time, i.e. the max time
• The Occ Mode entry on the keypad is set to Tenant Override. After the Tenant Override
Timer is set, the Occ Mode entry on the keypad reverts to auto after a 2 second time delay
• The Occ Mode entry on the keypad is set to Auto or Unocc, and a manual network
occupancy command is set to Bypass. After the Tenant Override Timer is set, the network
occupancy command reverts to Auto
Subsequent presses on the button, setting of the keypad occupancy entry to Tenant Override
again, or setting of the network occupancy command to Bypass again resets the Tenant
Override Timer to the Local Tenant Override Time.
The TOTime entry on the keypad can also be manually set to a non-zero value. In this case the
value begins timing down from the edited value.
Tenant Override Operation may be terminated by manually setting the Tenant Override
parameter on the keypad to zero or by disabling the unit.