Manual 2100-694B
Page
33 of 62
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.
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 51).
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.
9. Press ENTER key to save.
Economizer Operation
Model Number Based Economizer Blank-Off
Changing the
Vent Package
model number value to
a "B" (see Figure 54 on page 37) simulates a blank-
off plate configuration and will disable economizer
functions for the unit, with the exception of emergency
ventilation functions. When the vent package model
number value is changed to "B", the economizer control
type listed on screen A2 will change to
None
regardless
of system ventilation control type.
The economizer has four types of operation. The
first mode is "None" where the economizer is never
utilized, except for emergency purposes. The second
mode is "Dry Bulb" where the outdoor temperature is
the only consideration for economizer use on a free
cooling call. The third mode is "TempHum" where the
outdoor temperature and humidity are considered
for economizer use on a free cooling call. The fourth
mode is "Enthalpy" where the outdoor temperature,
humidity and calculated dew point are considered for
economizer operation on a free cooling call.
To change the economizer type:
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
Economizer
Setup A2
; press ENTER key.
5. Press ENTER key to scroll to
Control Type
(see
Figure 52).
6. Press UP or DOWN keys to change the
Type
desired
value to
None
,
Dry Bulb
,
TempHum
or
Enthalpy
.
NOTE:
The setpoint options on this page will change
based on what control type is selected. If
None
is selected, economizer setpoints will not be
displayed.
FIGURE 51
Adjusting Supply Air Temperature Differential
FIGURE 52
Economizer Setup A2
7. Press ENTER key to save the value and scroll to
the next parameter.
8. The cursor should now be on the
OD Temp Set
(Outdoor Temperature Setpoint) parameter.
9. Press UP or DOWN keys to change the parameter
to the desired value.
10. Press ENTER key to save the value and scroll to
the next parameter.
11. The cursor should now be on
On Diff
(Outdoor
Temperature On Differential) parameter.
12. Press UP or DOWN keys to change the parameter
to the desired value.
13. Press ENTER key to save the value and move to
the next parameter.
14. The cursor should now be on the
Humidity Set
(Outdoor Humidity Setpoint) parameter.
