Manual 2100-670
Page
27 of 32
FIGURE 38
Adjusting Supply Air Temperature Differential
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 38).
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
The economizer has four types of operation. The first
mode is "None" where the economizer is never utilized.
The second mode is "Dry Bulb Only" where the outdoor
temperature is the only consideration for economizer
use on a cooling call. The third mode is "Temperature
and Humidity" where the outdoor temperature and
humidity are considered for economizer use on a
cooling call. The fourth mode is "Enthalpy" where the
outdoor temperature, humidity and calculated dew
point are considered for economizer operation on a
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
Type
(see Figure 39).
6. Press UP or DOWN keys to change the
Type
desired value to
None
,
Dry Bulb
,
TempHum
or
Enthalpy
.
7. Press ENTER key to save the value and scroll to
the next parameter.
NOTE:
The following parameters are for the
temperature consideration for economizer use.
Applies to
Dry Bulb
,
TempHum
and
Enthalpy
type.
8. The cursor should now be on the
Outdoor Set
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
Off Diff
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 is now on the
Mixed FC Set
parameter.
15. Press UP or DOWN keys to change the parameter
to the desired value.
16. Press ENTER key to save the value.
17. Press the DOWN key to navigate to the
A3
screen.
NOTE:
This screen will not display if economizer
mode is set to
Dry Bulb
or
None
. Also, the
contents of the screen will change when type
is set to
Enthalpy
(see Figure 40 on page 28)
as compared to when type is set to
TempHum
FIGURE 39
Economizer Setup
