A
base
IOM67
12
February 2021 R0
83
Open Air
Proving
Combustion blower air
switch input (CB) has no
power for 60 seconds
after commanding the
combustion blower on /
Combustion blower air
switch input has no power
for 2 seconds during main
flame.
84
Shorted CB Air
Proving
Combustion blower air
switch input has power for
10 seconds before the
combustion blower has
been commanded on.
85
Plugged
Condensate
Blocked condensate
sensor reads less than
7kohms for more than 5
minutes.
86
High Limit
High limit safety tripped
due to excessively high
temperature.
89
Blocked Flue
Blocked flue input has
opened for more than 1
minute.
HE Alarms
91
Low Velocity Air
Switch
Occurs if the pressure
drops below the low
pressure setpoint during
modulation for more than
40 seconds
92
High Velocity
Air Switch
Occurs if the pressure
goes above the High
pressure setpoint during
modulation for more than
90 seconds
94
Low Pressure
Air flow too low to enable
heating.
95
Low Pressure
Sensor
Unable to zero the
pressure before the
damper has opened.
96
Very Low
Pressure
Occurs if the pressure
drops below the very low
pressure setpoint after
the purge has been
completed.
97
Far Sensor
Flame Failure
Occurs if a secondary
flame rod is enabled and
flame sensing is lost in less
than 20 seconds after the
pilot valve drops out on
consecutive attempts.
SH(X) Water Alarms
61
Tank High
Pressure
Overflow
Measuring elevated drain
temperature when not
draining.
62
Water Foaming
Erratic water level probe
sensing .
63
Failed Water
Supply
Expected time to fill to
water level probes not
achieved.
64
Failure to Drain
Expected time to clear
water level probes not
achieved.
65
Water Probe
Sequence
On fill, probe sensing is
reversed.
66
Duct High Limit
Trip
Duct humidity high limit
open.
67
Drain Sensor
Failure
NTC Type 2 drain sensor
outside of range.
68
Fill Valve Stuck
Open
Expected time to clear Full
Water Probe not
achieved.
