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disabled to allow economizer operation. This
is done because the compressor is disabled
below 0°F and the system would not have the
capability to cool.
High Supply Air Temperature Alarm
When the supply air temperature measurement is above
the outdoor air temperature setpoint (70°F) for the
economizer to be enabled for 120 seconds, an alarm
will be generated and the economizer will be disabled
until the cooling call has been removed. This alarm will
automatically reset once the economizer is no longer
disabled.
To change the high supply air temperature alarm:
1. Press MENU key to go to the Main Menu screen.
2. Press UP or DOWN keys and ENTER key to enter
USER password 2000.
3. Press UP or DOWN keys to scroll to
System Config
;
press ENTER key.
4. Press UP or DOWN keys to scroll to
Alarm Setup
(A5)
; press ENTER key.
5. Press ENTER key to scroll to
Hi and Diff
value (see
Figure 2.39).
6. Press UP or DOWN keys to change the differential
to the desired value.
7. Press ENTER key to save and scroll to the next
parameter.
FIGURE 2.39
Adjusting High Supply Air Temperature Differential
4. Press UP or DOWN keys to scroll to
Alarm Setup
(A5)
; press ENTER key.
5. Press ENTER key to scroll to
Lo and Diff
value (see
Figure 2.39).
6. Press UP or DOWN keys to change the differential
to the desired value.
7. Press ENTER key to save value and scroll to
Delay
.
8. Press UP or DOWN keys to adjust the delay value.
NOTE:
This delay is also applied to the high supply air
temperature alarm.
7. Press ENTER key to save.
Emergency Ventilation Mode
If the shelter temperature is above the high
temperature alarm 2 on the LV, the unit will be
commanded into emergency ventilation mode. In this
mode, the unit will open the economizer to 100%. The
compressor may run during this mode. This will stay
active until the LV returns the unit to normal operation.
This mode is only available when connected to the LV.
Model/Serial Number Configuration
The system will automatically configure some settings
based on the model number input into the unit. The
model and serial number are entered at the factory.
During a program update, the model and serial number
may be lost and need to be re-entered.
The unit will look at model number character number
10 to determine if the economizer should be disabled.
If the character is a E or e, the economizer operation
will be disabled.
The unit will look at model number characters 8 and 9
to determine how many heat stages are available. If the
characters are 0Z, 0z, MZ, Mz, mZ or mz, the unit will
be set to 0 stages of heat. If the characters are 05, m5
or M5, the unit will be set to 1 stage of heat.
Electric Heat Option
Electric Heat Components
Electric Heating Element
The unit is optionally equipped with a 5kw heat strip.
The heat strip is located next to the blower assembly
and uses resistive heat.
Thermal Overload
The heater assembly has a thermal overload wired in
series with the heating element. This device has a
cycling limit which opens at 130°F and resets at 80°F.
The limit is also equipped with a redundant thermal
fuse that will open at 150°F.
Low Supply Air Temperature Alarm
When the supply air temperature is below 45°F for
120 seconds, an alarm will be generated and the
economizer will be disabled until the cooling call has
been removed. This alarm will automatically reset when
the economizer is no longer disabled.
To change the low supply air temperature alarm:
1. Press MENU key to go to the Main Menu screen.
2. Press UP or DOWN keys and ENTER key to enter
USER password 2000.
3. Press UP or DOWN keys to scroll to
System Config
;
press ENTER key.
