32
DetaileD seQUeNce oF oPeratioN
saFEtY sEQuEncEs duRIng opERatIon
DraFt iNDUcer teMPeratUre saFetY switcH
If draft inducer temperature reaches temperature
safety switch setpoint, safety switch contacts open
immediately, closing gas valve
(light goes out)
.
Draft inducer runs through 30 second post purge and
switches off.
Circulator runs with thermostat on call for heat.
When temperature safety switch contacts remake
before end of call for heat, control goes into normal
light-off sequence.
loss oF coMBUstioN airFlow
I
f combustion airflow is lost while burner is firing (Differ
-
ential air pressure switch contacts open) gas valve will
be de-energized.
V
alve and flame lights go out.
Draft inducer runs through 30 second post purge.
I
f call for heat remains, ibc waits 5 minutes for airflow
to be re-established.
I
f airflow does not re-establish control lockout - problem
with combustion airflow.
P
urge light blinks.
Control
will automatically reset after 15 minutes.
loss oF FlaMe sigNal
I
f an established flame signal is lost while control expects
that the burner is operating, control will immediately de-
energize gas valve.
V
alve and flame lights go out.
Draft inducer runs through 30 second post purge.
Control will attempt to relight boiler 3 times. I
f flame
is not proven, control lockout - problem establishing
a flame signal.
V
alve light is blinking.
Control will
automatically reset after 1 hour.
HigH liMit coNtrol
If boiler water temperature reaches high limit
(aquastat) setpoint, high limit n.c. contacts open
immediately, closing gas valve.
V
alve and flame
lights go out.
Draft inducer continues to run for 30 second post
purge and switch off.
Circulator runs as long as thermostat calls for heat.
When high limit contacts remake before end of call for
heat - control goes into a normal light-off sequence.
castiNg teMPeratUre saFetY switcH
If burner operates when boiler has no water, aluminum
boiler sections heat up rapidly.
Casting temperature safety switch contacts will open,
breaking 24 volt power to ibc. power indicator light
goes out. Requires manual reset to re-close contacts.
Power light goes out.
circUlator PUMP
Circulator will be energized as long as thermostat calls
for heat during lockout.
Recovery from any lockout requires reset, which
can be accomplished by:
(a) R
emoving and reestablishing the thermostat’s
call for heat or turning the service switch off and
back on; or
(b) Waiting for the control to automatically reset after
15 minutes for loss of combustion airflow or one
hour for loss of flame.
