AERCO BMS 168 - Manual (Page 71)

H-1
Appendix H
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TROUBLESHOOTING
When a fault occurs in the boiler plant, the BMS flashes error messages at 2-second intervals
and the alarm contacts close. To cancel alarms (open contacts but message still displays),
press the RESET RATIO key The fault messages shown in Table H1 can occur in any mode of
operation, Constant Setpoint, Indoor/Outdoor Reset, or Remote Setpoint. Some of the most
common problems encountered in BMS operation are contained in Table H2.
Table H1 Error 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 4-to-20 mA and Constant
Setpoint modes. It does not display as an error message, and
will display only after pressing the AIR TEMP key.
OUTSIDE AIR TEMP
SENSOR ERROR
When in Indoor/Outdoor Reset Mode, the outside air temperature
sensor is either open, shorted, or not connected.
HEADER TEMP
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
INDOOR AIR TEMP
SENSOR ERROR
• Open indoor air temp. sensor: resistance greater than 240K ohms
(less than -40°F) .
Shorted sensor: resistance less than 240 ohms (over 300°F)
No sensor installed and Prop Band is adjusted to > 0°F/°F
SYSTEM ERROR,
INTERLOCK 1
Interlock 1 is open