Instruction manual

8 McQuay OM 920
Using the Keypad/Display
Navigation Mode
In the Navigation Mode, when a line on a page contains no editable fields all but the value
field of that line is highlighted meaning the text is white with a black box around it. When the
line contains an editable value field the entire line is inverted when the cursor is pointing to
that line.
When the navigation wheel is turned clockwise, the cursor moves to the next line (down) on
the page. When the wheel is turned counter-clockwise the cursor moves to the previous line
(up) on the page. The faster the wheel is turned the faster the cursor moves.
When the Back Button is pressed the display reverts back to the previously displayed page. If
the Back button is repeated pressed the display continues to revert one page back along the
current navigation path until the “main menu” is reached.
When the Menu (Home) Button is pressed the display reverts to the “main page.”
When the Alarm Button is depressed, the Alarm Lists menu is displayed.
Edit Mode
The Editing Mode is entered by pressing the navigation wheel while the cursor is pointing to a
line containing an editable field. Once in the edit mode pressing the wheel again causes the
editable field to be highlighted. Turning the wheel clockwise while the editable field is
highlighted causes the value to be increased. Turning the wheel counter-clockwise while the
editable field is highlighted causes the value to be decreased. The faster the wheel is turned the
faster the value is increased or decreased. Pressing the wheel again cause the new value to be
saved and the keypad/display to leave the edit mode and return to the navigation mode.
Service Timers
A user may override timers for a period of up to 240 minutes by setting the Service Timer to a
non-zero number. When the Service Timer is not zero, the times listed below are set to the
Service Time (Default = 20 seconds) instead of the normal values. This allows the unit to be
run through its operating states without having to wait for the normal time delays to expire.
These times revert to the standard values when the Service Time count down to zero or is set
to zero by the user.
The affected times are:
• Cooling Stage Time
• Heating Stage Time
• Start Initial Time
• Recirculation
• ZeroOATime
Rapid Start
The user may elect to initiate a rapid startup sequence at unit power up by setting the Rapid
Start flag to Yes. When this flag is set to Yes, the Service Timer is set to 10 minutes whenever
the power is reset to the controller.