Emerson Autochangeover Controllers AC8 - Manual (Page 80)

System and Control Options
72
7.10.6 Specify Staging
Staging allows a standby device to be turned On when a sensor detects a monitored point reaching a
specified setpoint. The AC8 continues to turn On additional standby units, if available, at specified
intervals.
Staging also turns Off devices as the condition returns to normal. Devices are turned off in a last-on /
first-off order, triggered by decreases of half the specified sensitivity increment.
Staging is OFF by default.
To change the Staging settings:
• From the Setup Operation Menu, choose Staging, as shown at
right, and press Enter ↵ .
• In the Activate/Deactivate screen, use the arrows ↑↓ to choose ON
to activate or OFF to deactivate the feature, then press Enter ↵ .
NOTE: If the sensor for the zone is not connected, a SENSOR
NOT CONNECTED message is displayed, shown below right.
Press Escape to return to the previous screen.
The sensor in the zone must be set to CONNECTED to turn stag-
ing on.
• Once the feature is activated (ON), set the following features in
the Staging screen:
• Use the arrow keys ↑↓ to set the Target sensor reading value
that will initiate the staging process.
• Press Enter ↵ to advance to Sensitivity.
• Use the arrow keys ↑↓ to set the Sensitivity that defines the
increment for the next change in the staging process.
The default value is 2.
• When finished, press Enter ↵ again.
The following example illustrates the staging process for a temperature sensor with a
Target setpoint of 70°F and a Sensitivity increment of 5°F.
Temperature Reaches Target Level: First Device Turned On
• When the temperature in Zone 1 reaches 75°F (target plus sensitivity), the AC8
turns On a cooling unit that has been on standby.
Temperature Rises by Sensitivity Increments: Second & Third Devices Turned On
• When the temperature reaches 80°F—an additional 5°F—the AC8 turns On a sec-
ond standby cooling unit.
• If the zone has a third standby unit and the temperature rises another 5°F to 85°F,
a third standby unit is turned On.
Temperature Returns to Normal: Devices Turned Off
• When the temperature drops from 85°F to 82.5°F (a decrease of 2.5°F, half the sen-
sitivity increment of 5°F), the third unit is turned Off.
• When the temperature falls to 77.5°F, the second device is turned Off.
• When the temperature falls below 75°F, the first device is turned Off.
Setup Operation Menu
AUTO SEQUENCING OFF
STANDBY TESTING OFF
FAILED STANDBY
N
↑↓
=NEXT
↵
=SELECT
HOLD DELAY : 10:00
RESTART
: 00:06
> STAGING : OFF
Activate / Deactivate
STAGING: OFF
↑↓
=NEXT
↵
=EDIT
Staging
STAGING: ON
TARGET: +0070.0
SENSITIVITY: +005.0
↑↓
=NEXT
↵
=SELECT
Message
(if sensor for zone is not
connected to AC8)
SENSOR NOT
CONNECTED