Trane UHMB060ACV3VA Installer's Manual page 50

Installer's Guide
•
Start and NO [NO] will now be displayed. With a
NO/NO question being asked, use the 3or4
arrows to select the YES and then press the
ENTER button.
•
Are you Sure and NO [NO] will now be displayed.
With a NO/ NO question being asked, use the
3or4 arrows to select the YES and then press the
ENTER button.
•
Turn 115VAC power off. When the Green LED on
the variable speed inducer drive goes out, turn
115 VAC power back on.
•
When the furnace is operating in the contingency
mode (stand alone operating cycle), the user
interface will display the following information. The
top line will say CNTNGNCY MODE. The bottom
line will show the duty cycle stage number STG
(1 or 2) selected, and the percent number 10-50
% selected.
•
All furnace operating controls, pressure switches
and communications between the IFC and the
variable speed inducer drive and the variable speed
indoor blower will be functional during contingency
mode operation of the furnace.
• The 3456 and ENTER buttons do not function
in the contingency mode of operation.
•
To exit the contingency mode of operation turn
off the 115 VAC power to the furnace.
•
The contingency mode will stop for any of the
following reasons:
(1) If the furnace IFC receives a signal from the
communicating comfort control. This will only
happen if the data wire "D" from the comfort
control has been reconnected to the furnace
IFC terminal board terminal "D".
(2) Power is removed from the furnace and then
turned back on.
(3) The Furnace IFC enters a RESET mode of
operation.
(4) A fault is detected by the furnace IFC. Fault
LED will be flashing an Alert Code.
24V CONTINGENCY MODE
An alternative method for the contingency mode can
be used by changing the mode of operation in the
Use Interface to 24V mode and installing a
conventional 24V comfort control.
To set this mode of operation:
Remove all wiring from the *CONT900 comfort
control and install a 24V comfort control. If the
comfort control requires a 24V common; connect
R and B to respective terminals. Connect a third
wire to "W". At the IFC, connect the same three
wires to the corresponding terminals.
W1 to W2 at the IFC. The stage delay between
W1 and W2 can be set by scrolling through the
User Interface. It is factory set to zero minutes
but can be adjusted to 5, 10, or 15 minutes.
50
IFC INDUCER LEARNING ROUTINE SEQUENCE
•
The furnace IFC will go through an inducer learning
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
initiated. The furnace IFC will not go through a
PS-3 inducer learning routine until it receives a
call for 100% (high) heat.
•
To ensure the furnace heating efficiency is
maintained the furnace IFC will repeat the inducer
motor learning 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, PS-2, and PS-3. They all have to be open before a
heating cycle can begin.
•
The furnace IFC sends a digital signal to the
variable speed inducer drive to run the inducer
motor at the preset factory 65% (medium) heat
RPM.
•
The furnace IFC waits for the PS-1 and PS-2
pressure switches to close. A 24 Volt AC signal is
sent to the furnace IFC when a pressure switch
closes.
•
If PS-1 and PS-2 do not close at the preset factory
65% (medium) heat RPM, the furnace IFC will
continue to signal the variable speed inducer drive
to increase the inducer speed in steps until PS-1
and PS-2 close or until the maximum RPM for 65%
(medium) heat is reached.
•
When PS-1 and PS-2 switches close, the furnace
IFC will then start the ignition cycle.
•
The IFC now starts the igniter warm up cycle.
•
Approximately 20 seconds later, the furnace
IFC will turn on the gas valve.
Jumper
18-CD30D1-9