Trane UHMB060ACV3VA Installer's Manual page 51

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
operation begins. The forty-five second time delay
allows the heat exchanger and the recuperative
cell to warm up.
•
The furnace IFC will now start its 65% (medium)
heat inducer learning routine.
• The furnace IFC will signal the variable speed inducer
drive beginning to reduce the inducer motor speed
in steps until the furnace IFC detects that PS-2 is
open.
•
When PS-2 opens, the furnace IFC will NOTE the
inducer motor RPM.
•
The furnace IFC then adds an additional number of
RPM to the 65% (medium) heat inducer motor
NOTED RPM until PS-2 closes.
•
The additional number of RPM plus this NOTED
RPM is the learned 65% (medium) heat inducer
operating RPM.
•
The furnace IFC now stores this learned operating
inducer RPM for 65% (medium) heat in its memory.
•
The furnace IFC will use this stored learned
operating inducer RPM for 65% (medium) heat calls
it receives in the future.
•
If the furnace IFC is still receiving a call for
low heat operation it will now start the learning
routine for 40% (low) heat.
•
The furnace IFC will then continue to reduce the
inducer motor RPM in steps until the furnace IFC
detects that PS-1 is open.
•
When PS-1 opens, the furnace IFC will NOTE the
inducer motor RPM.
•
The furnace IFC then adds an additional number of
RPM to the 40% (low) heat inducer motor NOTED
RPM until PS-1 closes.
•
The additional number of RPM plus this NOTED
RPM is the learned 40% (low) heat inducer operating
RPM.
•
The furnace IFC now stores this learned inducer
operating RPM for 40% (low) heat in its memory.
•
The furnace IFC will use this stored learned inducer
operating RPM for 40% (low) heat calls it receives
in the future.
•
Whenever the furnace is powered up or after a
RESET, the furnace IFC will not go through a
learning routine for 100% (high) heat until it
receives a call for 100% (high) heat.
18-CD30D1-9
Installer's Guide
PS-3 INDUCER LEARNING ROUTINE
•
When the furnace IFC receives a digital signal for
100% (high) heat from the comfort control it will
begin the PS-3 inducer learning routine.
•
The furnace will start the heating cycle in 65%
(medium) heat, if not already on, and then begins
the PS-3 inducer learning routine.
•
The furnace IFC will send a digital signal to the
variable speed inducer drive to run the inducer
motor at the preset factory 100% (high) heat RPM.
•
The furnace IFC waits for PS-3 pressure switch to
close. A 24 Volt AC signal is sent to the furnace IFC
when the pressure switch closes.
•
If PS-3 does not close at the factory preset 100%
(high) heat RPM, the furnace IFC will continue to
signal the variable speed inducer drive to increase
the inducer speed in steps until PS-3 closes or until
the maximum RPM for 100% (high) heat is reached.
• The furnace IFC enters a time delay so that the heat
exchanger and the recuperative cell warm up to
their high heat operating temperature. At the end
of this time delay, the inducer discharge air
temperature will be at its high heat operating
temperature and the density of the products of
combustion will be stabilized.
•
The furnace will now signal the variable speed
inducer drive to reduce the inducer speed in steps
until PS-3 opens.
•
When PS-3 opens, the furnace IFC will NOTE the
inducer motor RPM.
•
The furnace IFC then adds an additional number of
RPM to the 100% (high) heat inducer motor NOTED
RPM until PS-3 closes.
•
The furnace IFC now stores this learned inducer
operating RPM for 100% (high) heat in its
memory.
•
The furnace IFC will use this stored learned
inducer operating RPM for 100% (high) heat calls
it receives in the future.
•
If PS-3 is not closed when the inducer reaches its
maximum RPM, the furnace IFC will signal the
variable speed inducer drive to reduce the inducer
Motor speed in steps to its low heat LEARNED
SPEED.
•
The furnace IFC flashes its Red Fault LED three
times repeatedly. The furnace IFC will keep
operating at low heat for 10 minutes and then retry
the PS-3 learning routine.
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