Unit installation

IOMM ACZ/AGZ-3 ACZ / AGZ-BM 97
Table 57, Unit Enable Conditions
Unit Off
Input
Control Source
Setpoint
Remote
Input
Keypad
Entry
BAS
Request
Unit Enable
OFF x x x x OFF
x SWITCHES OFF x x OFF
ON SWITCHES ON x x ON
ON KEYPAD x OFF x OFF
ON KEYPAD x ON x ON
ON NETWORK x x OFF OFF
ON NETWORK OFF x x OFF
ON NETWORK ON x ON ON
NOTE: An “x” indicates that the value is ignored.
Unit Mode Selection
The operating mode of the condensing unit is set by the Available Mode Setpoint with options of
COOL and TEST. COOL mode is the standard mode of operation. TEST is a field test mode,
accessible only with the manager password. The unit test mode allows manual control of each
digital output.
Unit Test Mode
The unit test mode allows manual testing of controller outputs. Entering this mode requires the
following conditions:
• Unit OFF input = OFF (i.e., the entire chiller is shut down).
• Manager password active.
• Available Unit Mode setpoint = TEST
A test menu can then be selected to allow activation of the outputs. It is possible to switch each
digital output ON or OFF and set the analog outputs to any value.
When in test mode, the compressors may be turned on, but they will automatically shut off after 10
seconds.
Compressor Control
Compressor Sequencing
This section defines which compressor is the next one to start or stop. The next section defines
when
the start, or stop, is to occur.
Compressor sequencing is based primarily on compressor run-hours and starts. Compressors with
fewer starts will start before those with more starts. Compressors that have more run-hours will shut
off before those with less run-hours. In the event of a tie on number of starts, the lower numbered
compressor starts first. In the event of a tie on run-hours, the lower numbered compressor shuts off
first.
If possible, the number of running compressors on each circuit will be balanced. If a circuit is
unavailable for any reason, the other circuit is allowed to stage on all compressors.
Required Parameters
1. Number of starts for all compressors
2. Number of run hours for all compressors
3. Status of all compressors (Available/Unavailable)
4. Compressor number