Instruction manual

62 McQuay OM 920
Operator’s Guide
Operator’s Guide
The following “Operator's Guide” sections provide information regarding the day-to-day
operation of the MicroTech III Unit Controller. Topics covered are such common tasks as
scheduling, displaying and clearing alarms, and setting the controller for manual operation.
Figure 6: State Diagram
The transition from any operating state to another is graphically represented in this figure.
With a “start up” command from an Off State the unit will always go into the “Start Up” state
of operation for 3 minutes (adjustable). Next, it will transition into the “Recirculation” state of
operation for another 3 minutes (adjustable) before finally going into the Fan Only state of
operation. Then, based on sensor inputs it will go into any of the 4 remaining states of
operation - heating, cooling, economizer, or minimum discharge air heating.
Determining Unit State
The unit will operate in one of eight operating states. The current state will be displayed by the
Unit State parameter in the system summary menu.
In the Off State, all heating, cooling, and fans are off. The alarm output indicates the type of
alarm, if any, that is active.