50
Since the controller interprets this as an issue that needs technical
assistance, the unit can only be reset from its HMI BACview tool.
WATERSIDE ECONOMIZER MODE
If the entering water temperature is less than the set point 55°F
(adjustable) the unit will transition to economizer mode:
• Disable mechanical cooling stage 1 operation for mini-
mum of 12 minutes.
• Enable economizer valve.
• Waterside economizer will operate until the entering water
temperature reset value is reached; default is 58°F (adjust-
able).
When in economizer mode, if the entering water temperature
reaches the reset value in less than 5 minutes, the first stage of me-
chanical cooling operation will be disabled for at least 5 minutes.
In economizer operation, if the unit requires additional stages of
mechanical cooling, the controller will command them accord-
ing to the unit demand percentage calculated by the Cooling
PID. If additional stages of cooling were running those will be
maintained.
The fan will continue to modulate to meet the static pressure set
point, the economizer valve will be commanded to open, and the
economizer will be treated as the first stage of cooling.
LEAVING WATER TEMPERATURE (LWT)
The controller will monitor the leaving water temperature. Alarms
will be provided as follows:
• High Leaving Water Temp: If compressor(s) is running
and the leaving water temperature is greater than 135°F
(adjustable).
• Low Leaving Water Temp: If compressor(s) is running and
the leaving water temperature is less than 33°F (adjustable).
• Leaving Water Sensor Failure: If leaving water sensor out-
side of normal operating limits. Should a High or Low
Leaving Water Temperature Alarm occur, the call for cool-
ing will be removed.
UPM Fault Monitor
The controller will monitor both Unit Protection Modules (UPM1
and UPM2) fault inputs.
Upon hard lockout alarm, compressors are disabled by the UPM
board.
Alarms will be provided through BACnet point current alarm
(AV:17) as follows:
• HP1: High Pressure Alarm (circuit 1)
• HP2: High Pressure Alarm (circuit 2)
• LP1: Low Pressure Alarm (circuit 1)
• LP2: Low Pressure Alarm (circuit 2)
• HP3: High Pressure Alarm (circuit 3)
• HP4: High Pressure Alarm (circuit 4)
• LP3: Low Pressure Alarm (circuit 3)
• LP4: Low Pressure Alarm (circuit 4)
• FRE: Freeze Alarm
• FRE2: Freeze Alarm
• CON: Condensate Alarm B
• RN: Brownout Alarm
Troubleshooting
COMMUNICATION LEDS
The LEDs indicate if the controller is speaking to the devices on
the network. The LEDs should reflect communication traffic
based on the baud rate set. The higher the baud rate the more solid
the LEDs become.
The Run and Error LEDs indicate controller and network status.
See Table 28 for Communication LEDs and Table 29 for Run and
Error LEDs.
Table 28 — Communication LEDs
NOTE: The I/O Flex 6126 controller is protected by internal solid-state
polyswitches on the incoming power and network connections. These
polyswitches are not replaceable, but they will reset themselves if the
condition that caused the fault returns to normal.
LEDS
STATUS
POWER
Lights when power is being supplied to the controller.
RX
Lights when the controller receives data from the network segment; there is an Rx LED for Ports 1 and 2.
TX
Lights when the controller transits data from the network segment; there is an Tx LED for Ports 1 and 2.
RUN
Lights based on controller health.
ERROR
Lights based on controller health.