74 McQuay OM 920-1
Operator’s Guide
Setting Controller Date and Time
The controller uses the date and time to execute its internal scheduling functions. The current
time and date will not be lost if the unit is turned off for up to forty-eight hours. The clock and
date are settable from the keypad via the following path: Extended Menus/Time/Date. The
time of day can be set by entering the hour (00-23), minute (00-59), and second (00-59) into
three fields of the Current Time. Note that MicroTech III uses “military” time. The current
date can be set by entering the date (00-31), month (01- 12) and year (1999-2155) into the
three fields of the Current Date.
Internal Daily Schedule
An internal Daily Schedule provides one start time and one stop time for each of the seven
days of the week and for holidays. When the Occ Mode= parameter is set to “Auto”, and the
unit is not disabled for other reasons, it starts and stops according to the controller internal
schedule. The parameter is adjustable via the following path: Standard Menus/Daily Schedule.
Holiday Scheduling
The operator may select the days when start and stop times for holidays are used by selecting a
start date and an end date for up to ten periods during the year by using the holiday scheduling
feature. Whenever a holiday period occurs, the controller uses the Holiday Schedule start and
stop time for the period. For example, assume that Christmas Eve occurs on a Thursday. The
building is shut down on both Christmas Eve and Christmas Day, but operates normally on the
weekend. This holiday period would be scheduled by setting the Holiday Schedule to “00:00-
00:00” and setting the Holiday Period to “12/24/08 - 12/25/08.” The parameter is adjustable
via the following path: Standard Menus/Holiday Schedule.
One Event Scheduling
A One-Event Schedule is provided so that one operating period can be scheduled without
affecting the regular internal schedule. A start date/time and an end date/time can be set.
The unit can be scheduled to operate during a specified period by using this feature. During
the specified period defined by the One Event Beginning Date/Time and One Event Ending
Date/Time parameters the unit starts up and runs continuously regardless of any other time
scheduling functions. For example, assume that a space served by the unit is occupied for a
special event on March 12 from 5:00 p.m. to 10:00 p.m. when the normal time scheduling has
the unit shut off after 4:00 p.m. on that date. This event can be accounted for by setting the
One Event Beginning Date/Time to “3/12/08 @ 17:00:00” and the One Event Ending
Date/Time to “3/12/08 @ 22:00:00.”
The parameter is adjustable via the following path: Standard Menus/One Event Schedule.
Optimal Start
When Optimal Start is active (Optimal Start = Yes), an early start time is determined before
each scheduled start. The parameter is adjustable via the following path: Standard
Menus/Optimal Start. The schedule must be based on an internal schedule or a signal via a
connected network that indicates time to occupancy. The controller uses start history, outdoor
air temperature and space temperature to determine when the unit should start. The unit may
start up to four hours before the scheduled occupancy time. Optimal start based on heating
operates when the space temperature is below the Zone Heating Spt by ½ the Zone Htg
Deadband. Optimal start based on cooling operates when the space temperature is above the
Zone Cooling Spt by ½ the Zone Clg Deadband. If space temperature is between the above
two points, the unit starts at the occupancy time.
External Time Scheduling
An external time clock can be used to schedule unit operation. This is accomplished by a field
supplied external time clock signal in the form of a set of dry contacts wired across terminals
101 and 102 on the unit field terminal block TB2. In this case, all internal daily schedules
should be set to “00:00-00:00” (default setting).
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