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McQuay OM 920-1
Keypad/Display Menu Structure
Eng Units
is an adjustable item to indicate if the unit is to display English or Metric units of
measure.
Unit Name
is an adjustable item used to set a unique name for the controller.
Timer Settings Menu
Service Time
is an adjustable item that sets the amount of time the internal control timers can
be temporarily sped up.
Startup
is an adjustable item that sets the time in seconds that the unit will perform its startup
operation.
Recirculate
is an adjustable item that sets the time in seconds that the unit operates with only
the fan, recirculating the building air upon unit start up.
Zero OA Time
is an adjustable item that sets the time in minutes that the outdoor air damper
stays at a zero position upon unit start up.
Tnt Override
is an adjustable item that sets the amount of time the unit will go into operation
when the tenant override function is activated. Tenant override can be activated by the space
sensor button, the network occupancy mode parameter or the keypad Occ Mode= parameter.
Post Heat
is an adjustable item that sets the duration of the post heat function available on
VAV units.
Password
is an adjustable item that sets the amount of time in minutes that the controller will
allow access to applicable menus without re-entering the necessary password. If the keypad
display remains idle for this time period, the display will revert to the “main menu” requiring a
re-enter of the password.
Low DAT
is an adjustable item that sets the duration of a time period upon unit start up during
which the Low Discharge Temperature fault is ignored. This may be particularly important in
colder climates when a unit has been off for a significant time period during which the unit,
including the discharge air temperature sensor, has become very cold. This time period allows
the unit to run long enough to turn the unit heat on and warm the discharge sensor above the
alarm limit, preventing nuisance unit alarm shutdown. This time period begins when the
supply fan starts.
ClgStateDelay
is an adjustable item that sets the amount of time between the fan only
operating state and the mechanical cooling state. The unit will not enter the mechanical
cooling state until this time has passed. This only applies on discharge control units following
morning warm up heating operation.
Bypass Valve
is an adjustable item that sets the duration of time the bypass valve is to be
opened prior to entering the economizer (waterside) or cooling operating state on unit with a
water cooled condenser. This is to allow enough time for the water flow switch and the
entering water temperature to be checked before the unit begins economizer or cooling
operation.
Table 25: Timer Settings Menu
Menu Display Name Item Display Name
Default Setting
Range
Password Level
Timer Settings
Service Time=
0min
0-240min
4
Start Up=
180s
1800s
4
Recirculate=
180s
3600s
4
Zero OA Time=
0min
0-240min
4
Tnt Override=
120min
0300min
4
Post Heat=
0s
0-180s
4
Password=
10min
3-30min
4
Low DAT=
6min
0-60min
4
ClgStateDelay=
300s
0-600s
4
Bypass Valve=
300s
0-600s
4
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