LX Series Unit Ventilator Controller User's Guide78
• This preceding condition exists for a length of time greater than the alarm
delay.
CO
2
Levels
While this alarm uses an offset, the alarm only sounds when the following
conditions are present:
• The CO
2
concentration is greater than the setpoint + the offset.
• This preceding condition persists for a length of time greater than the alarm
delay.
An alarm does not sound when the CO2 concentration is less than the
setpoint - the offset.
Discharge Temperature and Auxiliary Alarm
Both the Discharge Temperature and Auxiliary alarms have an alarm delay and
high and low limit. In this case, the alarm becomes active when both of the
following occur:
• The monitored temperature is outside of the range marked by the high and low
limits.
• This preceding condition exists for a length of time greater than the alarm
delay.
Mixed Air Temperature
Mixed air temperature alarm protects the cooling coils from freezing. The alarm
becomes active when both of the following conditions are present:
• The monitored temperature is less than the low limit.
• This condition exists for a length of time greater than the alarm delay.
Fan Alarm
The Fan alarm applies to the fan state only. The fan alarm becomes active when
one of following conditions occurs for a time period greater than the alarm delay:
• The fan command is ON, and the fan input differs from the fan output, or the
fan current is lower than the fan current threshold, or
• The fan command is OFF, and the fan input differs from the fan output, or the
fan current is higher than the fan current threshold.
Whether a digital fan speed is ON or OFF, a decision is made by monitoring the
fan speed or fan current. The alarm delay must be long enough to allow the fan to
reach the ON or OFF stage. The fan speed or fan current level is set in the
Fan-Valve Configuration screen.
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