Instruction manual
Table Of Contents
- Introduction
- Using the Keypad/Display
- Keypad/Display Menu Structure
- System Summary Menu
- Standard Menus
- System Menu
- Occupancy Menu
- Temperature Menu
- Flow Summary Menu
- Supply Fan Speed Menu
- Return/Exhaust Fan Speed Menu
- Cooling Menu
- Head Pressure Menu
- Evap Condensing Menu
- Economizer Menu
- Min OA Damper Menu
- Heating Menu
- Energy Recovery
- Dehumidification Menu
- Daily Schedule Menu
- One Event Schedule Menu
- Holiday Schedule Menu
- Optimal Start Menu
- Operating Hours Menu
- Extended Menus
- Unit Setup Menu
- Timer Settings Menu
- Time/Date Menu
- Supply Fan Setup Menu
- Return/Exhaust Fan Setup Menu
- Zone Temperature Setup Menu
- Compressor Setup Menu
- Head Pressure Setup Menu
- Chilled Water Setup Menu
- Economizer Setup Menu
- Design Flow Setup Menu
- Heating Setup Menu
- Dehumidification Setup Menu
- Alarm Out Configuration Setup Menu
- Alarm Limits Setup Menu
- Manual Control Menu
- LON/BACnetIP/BACnetMSTP Setup Menu
- Active Alarm Menu
- Alarm Log Menu
- Advanced Menus
- Unit Configuration Setup Menu
- Save/Restore Menu
- Alarm Delays Setup Menu
- Analog Input Status Menu
- Universal I/O Status Menu
- Digital Input Status Menu
- Digital Output Status Menu
- Adv Setup Settings Menu
- Adv Status Parameters Menu
- Alarms
- Operator’s Guide
- Determining Unit State
- Off Operating State
- Start Up Operating State
- Recirculating Operating State
- Heating
- Economizer
- Mechanical Cooling
- Determining Unit Status
- Determining Control Mode
- Determining Cooling Status
- Determining Heat Status
- Determining Economizer Status
- Determining Cooling Capacity
- Determining Heating Capacity
- Determining Supply Air Fan Capacity
- Determining RF/EF Capacity
- Determining Outside Air Damper Position
- Determining Emergency Mode
- Determining Application Mode
- Determining Occupancy Status
- Determining Occupancy Mode
- Determining Occupancy Source
- Unoccupied Operation
- Scheduling
- Temperature Control Configurations
- Heat/Cool Changeover
- Dehumidification
- Energy Recovery
- Outside Air Damper Control
- Outside Air Damper Control, Two Position
- Special Procedures for Units with WRV and More Than Two Circuits.
- Water Pump Control
- Cooling: Multistage
- Cooling: Modulating
- Heating Control
- Modulating
- Min DAT
- Indoor Air Fan - On/Off Control
68 McQuay OM 920
Operator’s Guide
Determining Heat Status
Htg Status is a status item which indicates whether or not heating is currently allowed. If
heating is disabled, the reason is indicated. The current Heat Status can be viewed via the
following path: Standard Menu/System/Htg Status.
The following are descriptions of heating status states:
Enabled
Heating is enabled if all the following are true:
• Heating capability is provided
• Control mode is not set via the System Menu to fan only or cool only
• Control mode is set via the System Menu to auto and not disabled via a network command
• The outdoor air temperature (OAT) is low enough for operation
None
Heating capability is not provided.
Off Ambient
The OAT is too high for operation. The OAT becomes too high for operation when the OAT
rises above the OAT heating lockout set point. OAT becomes low enough for operation when
the OAT drops below the OAT heating lockout set point by more than the Heating Lockout
Differential.
Off Network
Control Mode is set via the System Menu to auto and the unit is disabled via a network
command.
Off Manual
Control mode is set to Fan Only or Cool Only via the System menu.
Determining Economizer Status
Econo Status is a status item which indicates whether or not economizer operation is currently
allowed. If economizer operation is disabled, the reason is indicated. The current Economizer
Status can be viewed via the following path: Standard Menu/System/Econo Status.
The following are descriptions of economizer status states.
Economizer is enabled if all the following are true:
• Economizer capability is provided
• Control mode is set via the System menu to auto and not disabled via a network command
• Dehumidification operation is not enabled
• The unit is configured for waterside economizer and the EWT is below the mixed air
temperature minus the EWT differential or the unit is configured for airside economizer, the
enthalpy switch input indicates low enthalpy, and the outdoor air temperature (OAT) is low
enough for operation
None
Economizer capability is not provided.