A base
IOM67 11 February 2021 R0
ALARMS
The low limit setpoint is
the lower of 40°F or 15°F
below the discharge air
setpoint. 4 minute bypass
time.
VFD Feedback is greater
than the minimum VFD
speed for more than 30s
with the supply fan output
off.
Air SA Proving switch
shorted on start up.
Air Proving switch opens
during operation for 30s
or the VFD feedback drops
below the minimum speed
for 30 seconds.
Discharge Air
Sensor Failure
Discharge Air sensor is
outside of its range for
10s.
Ambient Air
Sensor Failure
Outdoor Ambient sensor
is outside of range for 10s.
The damper end switch is
made before energizing
the damper output.
Indication damper end
switch not made after
actuator is energized.
Loss of communication to
CD-XM (if used).
Gas valve feedback has
power before the FR and
SR contact are energized.
Gas valve actuator
feedback is greater or less
than the demand.
High limit safety tripped
due to excessively high
temperature.
Received a gas valve
feedback within 500ms of
activating the Flame relay
output.
Gas valve feedback has no
power after 1 minute of
enabling the Flame relay
output.
Combustion blower motor
RPM is greater or less
then the demand.
Timed event.
Combustion blower does
not exceed 3000 rpm
during purge.
Combustion rpm speed
sensor has a value greater
than 500 rpm for 60
seconds before the
combustion blower has
been commanded on.
Blocked condensate
sensor reads less then 7kΩ
for more than 5 minutes.
Blocked flue input is open
for more than 1 minute.
Combustion blower
frequency has exceeded
60 Hz ( 3590 RPM)
Air Actuator
Out of range
Air Actuator Feedback Is
greater or less then the
demand. Tolerances and
timing vary depending on
mode of operation.