Ifc Inducer Learning Routine Sequence - Trane ACONT900AC43UA Service Manual

Furnace Sequences Of Operation

IFC Inducer Learning Routine Sequence

Note:
Stage 1 = 40% (low) heat, Stage 2 = 100% (high) heat
· The furnace IFC will go through an inducer learning
3
routine for three pressure switches.
· The learning routine is done to determine the correct
amount of ventilation air for complete combustion.
· The inducer motor speed may be different for each
installation due to the different length and size of the
ventilation pipe, exhaust vent pipe, number of pipe
fittings used, and the type of vent cap installed.
· The inducer learning routine is repeated each time
the power to the furnace is interrupted. Once power is
restored and the furnace receives a call for heat, the
PS-1, PS-2 inducer learning routine will be
5a 5b
initiated. The furnace IFC will not go through a PS-3
inducer learning routine until it receives a call for
5c
100% (high) heat.
· To ensure the furnace heating efficiency is maintained
the furnace IFC will repeat the inducer motor learning
3
routine after:
150 Cycles at 40% (low) heat
100 Cycles at 65% (medium) heat
50 Cycles at 100% (high) heat
PS-1, PS-2 Inducer Learning Routine
· The furnace IFC checks pressure switches PS-1,
3
PS-2, and PS-3.
5a 5b
before a heating cycle can begin.
· The furnace IFC sends a digital signal to the variable
3
speed inducer drive to run the inducer motor
6a
preset factory 65% (medium) heat RPM.
· The furnace IFC waits for the PS-1
3
pressure switches to close. A 24 Volt AC signal is
5b
sent to the furnace IFC when a pressure switch closes.
GF - A 6
5a 5b 5c
They all have to be open
5c
6b
and PS-2
5a
IFC Inducer Learning Routine Sequence
· If PS-1 and PS-2
5a
factory 65% (medium) heat RPM, the furnace IFC
will continue to signal the variable speed inducer drive
6a
to increase the inducer speed in steps until PS-
1 and PS-2
5a
for 65% (medium) heat is reached.
· When PS-1
furnace IFC
3
· The IFC now starts the igniter
3
· Near the end of the warm up cycle the furnace IFC
will turn on the gas valve.
3
NOTE:
The furnace lights at approximately 65% of capacity.
· When the burner flame is detected by the furnace IFC,
a forty-five second time delay for indoor blower
3
operation begins. The forty-five second time delay allows
the heat exchanger and the recuperative cell to warm
up.
· The furnace IFC
heat inducer learning routine.
· The furnace IFC
inducer drive
6a
speed in steps until the furnace IFC detects that
6b
PS-2 is open.
5b
· When PS-2
5b
the inducer motor
· The furnace IFC
of RPM to the 65% (medium) heat inducer motor
at the
NOTED RPM until PS-2
6b
· The additional number of RPM plus this NOTED RPM
is the learned 65% (medium) heat inducer operating
RPM.
do not close at the preset
5b
close or until the maximum RPM
5b
and PS-2 switches close, the
5a 5b
will then start the ignition cycle.
7
8
will now start its 65% (medium)
3
will signal the variable speed
3
beginning to reduce the inducer motor
opens, the furnace IFC
RPM.
6b
then adds an additional number
3
closes.
5b
3
warm up cycle.
will NOTE
3