AERCO Control System (ACS) - Manual (Page 81)

MC2: 04/23/13 Page 81 of 144
GF-131
AERCO Control System (ACS)
Installation, Operation, and Maintenance Manual
OMM-0081_0D
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, New York 10913 • Phone: 800-526-0288
5. TROUBLESHOOTING
5.1 Fault Messages And Common Problems
When a fault occurs in the boiler plant, the ACS flashes fault messages at 2-second intervals
and the Fault Alarm (FLT ALARM) relay contacts are closed. The red FAULT indicator on the
front panel will also light. To cancel the alarm (open relay contacts), press the CLEAR key on
the ACS keypad. The FAULT indicator will turn off, however the fault message will continue to
be displayed.
The fault messages shown in Table 5-1 can appear when the ACS is operating in any of the
three basic modes (Constant Setpoint, Outdoor Reset, or Remote Setpoint).
Table 5-2 lists some common problems that may occur during ACS operation and provide
Probable Causes and Corrective Action for each listed Probable Cause.
Table 5-1: Fault Messages
Fault Message Description & Possible cause
OUTSIDE AIR TEMP
NOT CONNECTED
• Open outside air temp. sensor: resistance greater than 240K ohms
(less than -40°F)
• Shorted outside air temp. sensor: resistance less than 1K ohms
(greater than 200°F)
No sensor connected
Note: Displays only in Remote Setpt and Constant
Setpoint modes. I
OUTSIDE AIR TEMP
SENSOR ERROR
When in Outdoor Reset Mode, the outside air temperature sensor is
either open, shorted, or not connected.
HEADER SENSOR
ERROR
• Open header sensor: resistance greater than 240K ohms (less
than -40°F)
• Shorted header sensor: resistance less than 240 ohms (over
300°F)
Sensor not installed
INTERLOCK 1 ERROR Interlock 1 is open
INTERLOCK 2 ERROR Interlock 2 is open
HIGH DT
(next to RETURN
TEMP reading)
The Delta-T range has been exceeded by 18°F. The system must cool
down to below “Header Temp + Delta-T” before the BMS will return to
normal operation.
NOTE
If upon startup, the system is locked out because the Header
temperature is more than “Delta-T + 18°F” above the return
temperature, first set the RETURN SENSOR MODE to OFF and
allow the system to warm up before setting it back to NORMAL.
This will prevent the boilers from cycling too much at cold
startup.