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S S e e q q u u e e n n c c e e o o f f O O p p e e r r a a t t i i o o n n
7. When the temperature is lowered enough to satisfy
the thermostat setting, contacts R-Y1-Y2-G will
open.
8. The OD unit shuts off and the indoor blower shuts
off, unless a blower off delay has been enabled in
the IFC setup menu options. The seven segment
LED will read "IDL" = Idle, no thermostat demand.
V V a a r r i i a a b b l l e e S S p p e e e e d d I I n n d d u u c c e e r r L L e e a a r r n n i i n n g g R R o o u u t t i i n n e e
The purpose of the learning routine is to determine the
most efficient inducer operating speed for the furnace
in a given heat stage. On a call for gas heat, or
transition to a given gas heat stage, the inducer is
commanded to a speed in order to close the pressure
switch for that stage.
N N o o t t e e : : NOTE: Gas manifold measurements or
adjustments must not be made until the learning
routine for each stage has been successfully
completed.
There are two learning routines, one for 1
nd
heat and another for 2
routine is separate and will occur:
1. Upon initial commissioning of the furnace
2. When power to the furnace has been interrupted
3. After the below number of heating cycles has been
reached
st
a. 150 1
stage cycles
nd
b. 100 2
stage cycles
s s t t
1 1
S S t t a a g g e e H H e e a a t t
st
1. When 1
stage gas heat is requested, the variable
speed inducer is energized and will run at the
predetermined factory default 1
speed. Once the ignition process and the blower on
delay have successfully completed the IFC will
begin the Inducer Learning Routine as outlined
below
P P S S 1 1 c c l l o o s s e e s s a a t t d d e e f f a a u u l l t t s s p p e e e e d d
a. The inducer speed is reduced every 2 seconds
until PS1 opens
b. At the time PS1 opens, the IFC stores the
inducer RPM
116
st
stage gas
stage gas heat. Each learning
st
stage inducer
c. The inducer RPM is then raised every 3 seconds
to re-close PS1. Upon PS1 closing, the IFC has
now learned the most efficient inducer speed for
st
1
stage gas heat operation.
P P S S 1 1 d d o o e e s s n n o o t t c c l l o o s s e e a a t t d d e e f f a a u u l l t t s s p p e e e e d d
The IFC will increase the speed of the inducer until:
a. The maximum RPM for 1
reached
b. Or PS1 closes
Once PS1 closes, the learning routine will begin
as stated above.
n n d d
2 2
S S t t a a g g e e H H e e a a t t
nd
1. When 2
stage gas heat is requested, the variable
speed inducer will run at the predetermined factory
nd
default 2
stage inducer speed.
P P S S 2 2 c c l l o o s s e e s s a a t t d d e e f f a a u u l l t t s s p p e e e e d d
a. The inducer speed is reduced every 2 seconds
until PS2 opens
b. At the time PS2 opens, the IFC stores the
inducer RPM
c. The inducer RPM is then raised every 3 seconds
to re-close PS2. Upon PS2 closing, the IFC has
now learned the most efficient inducer speed for
nd
2
stage gas heat operation.
P P S S 2 2 d d o o e e s s n n o o t t c c l l o o s s e e a a t t d d e e f f a a u u l l t t s s p p e e e e d d
The IFC will increase the speed of the inducer until:
a. The maximum RPM for 2
reached
b. Or PS2 closes
Once PS2 closes, the learning routine will begin
as stated above. If PS2 does not close after
reaching the maximum RPM, a PS2 open error
will be reported and the furnace will continue to
st
run in 1
stage for 10 minutes and retry 2
stage. This process will repeat until the request
nd
for 2
stage heat is removed.
st
stage gas heat is
nd
stage gas heat is
nd
S9V2-VS-SVX001-1C-EN
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