Unit installation
48 OMRCPMICRO
Front panel mount heat/cool switch
point sets the delay time between the current cooling stage and the next stage up request. The stage down
request time delay is a fixed 1/3 ratio of the stage up delay.
The minimum Start/Start and Stop/Start timers provide protection against compressor short cycling. During
normal operation the Compressor Interstage Timers provide a time delay between cooling or heating stages.
Menu #17: Head Pressure Set Points
—The set points for head pressure control are adjusted from within this menu. The Minimum Lift Pressure is
the minimum differential pressure to be maintained across the expansion valve. The dead band defines the
pressure differential range within which no fan staging will occur. If the head pressure moves outside of the
deadband, the controller will integrate the pressure error over time. When the Pound/Second exceeds the
Stage Up Error or Stage Down Error set point, the controller will adjust the fan staging up or down to bring the
head pressure back within the deadband. Refer to the section on head pressure control in this manual for
details.
Menu #18: Demand Limit
—The Demand Limit set point defines the maximum number of cooling stages allowed by an external demand
limit signal. The actual remote demand limit signal level in milliamps is also displayed here. Figure 8, Figure 9
and Figure 10 detail the effect that the remote demand limit signal will have on the chiller capacity.
Chiller/Templifier—Applicable when
ChlTmp operation is selected from Menu
23 (Templifier heat pumps only). In place
of demand limit input, a 0 or 5 volts
signal from a unit mounted switch allows
the unit to run in heat (0 volts - switch
open) or cool (5 volts - switch closed)
modes. Menu 18 displays the signal
result; Chl/Tmp Sig=Temp denotes
heating mode and Chl/Tmp Sig=Chil
denotes cooling mode.
Menu #19: Time/Date
—The MicroTech controller uses an internal calendar and clock to provide automatic operation for each day of
the year. Provision is made for Manual Override to accommodate unscheduled building occupancy. Press the
Control key to enter the control area of the menu structure then press the Next Menu key until the display
shows Menu Item #24, Set Date/Time. If the date is incorrect, press the Incr or Decr key and the controller will
prompt you for your password. When you have entered the correct password, the controller will return to the
Set Date/Time display. Press the Incr or Decr keys to scroll the month up or down. Press the Enter key when
the display shows the correct month. The cursor will advance to the Date position on the display which can
be set in the same manner. After pressing the Enter key to set the Date, the cursor will advance to the Year
position on the display. Use the Incr, Decr, and Enter keys to set the correct Year.
Press the Next Item key. The display will show the current Day, Hour, Minute and Second. If this information
needs to be changed, follow the same procedure used to set the Date in the previous section.
Menu #20: Daily Schedule
—This section will help you to set the Daily Start/Stop time for automatic operation of the chiller. Pressing the
Next Menu key and the Next item key will advance the display to the Daily Time Schedule. This is where the
Start and Stop times for each day of the week will be set using the 24 hour format. Beginning with Sunday, use
the Incr and Decr keys to set the desired start and stop time and press the Enter key to store the information in
the controller. If the chiller is to be programmed to run continuously 24 hours a day, set the times as follows:
(Stop=23:59; Start=00:00). Press the Next Item key to advance through the remaining week days and Holiday
Start/Stop times.
Menu #21: Holiday Date
—Up to 14 holiday dates may be entered. When the MicroTech controller's current date matches a date set in
the holiday schedule, the normal daily start/stop times are replaced by the holiday start/stop times which were
set in the previous section. At the date prompt, use the Incr and Decr keys to set the first holiday month and
press Enter to advance to the Day position of the display. Use the Incr, Decr and Enter keys to set the first day
of the holiday. Press Next Item key to advance to Holiday 1 Duration. If the scheduled holiday spans more