18-CD26D1-10 43
Installer’s Guide
INSTRUCTIONS TO THE OWNERS
WARNING
!
EXPLOSION HAZARD
IN THE EVENT THAT ELECTRICAL, FUEL OR ME-
CHANICAL FAILURES OCCUR, SHUT OFF THE GAS
SUPPLY AT THE MANUAL GAS SHUT OFF VALVE,
LOCATED ON THE SUPPLY GAS PIPING COMING
INTO THE FURNACE, BEFORE TURNING OFF THE
ELECTRICAL POWER TO THE FURNACE. CONTACT
SERVICER.
FAILURE TO FOLLOW THIS WARNING COULD RE-
SULT IN PROPERTY DAMAGE, PERSONAL INJURY
OR DEATH.
BURNER BOX TEMPERATURE LIMIT DEVICE
All models are equipped with a manual reset temperature
limit located on the Burner Box. In case of excessive tempera-
ture, the limit will open and cause the circuit to open which
shuts off all flow of gas.
CONDITIONS THAT AFFECT SYSTEM
OPERATION
1. EXCESSIVE COMBUSTION PRESSURE (WIND IN
EXCESS OF 40 M.P.H.) VENT OR FLUE BLOCKAGE
On a call for heat, the Variable Speed Draft Inducer must
first ramp up to speed and close the Pressure Switch
before the ignition sequence is allowed to begin. If the
Pressure Switch does not close, the motor will ramp up to
maximum speed and continue to operate there for about
1 minute.
After one minute, the Integrated Furnace Control will
turn the motor off for about 30 seconds and then back on
in an attempt to reestablish proper operation. This
condition is indicative of a highly restricted or blocked
inlet or outlet vent pipe or a failed Pressure Switch.
If pressure against induced draft blower outlet becomes
excessive, the Pressure Switch will open. If the Pressure
Switch is open for more than 3.5 seconds, the variable
speed draft inducer will speed up and attempt to close
the Pressure Switch. If the Pressure Switch is not closed
within 12 seconds or if the maximum speed of the motor
is reached, the draft inducer sends a Fault signal to the
Integrated Furnace Control. If the unit is operating in
Second Stage, an Inducer Fault will cause the Furnace
Control to transition the system to First Stage and it
will operate there for 10 minutes before attempting to
run again in Second Stage. If the unit is operating in
First Stage, an Inducer Fault will cause the Furnace
Control to shut the system down and wait 30 seconds
before attempting to reestablish operation in First
Stage.
2. LOSS OF FLAME
If loss of flame occurs during a heating cycle, or flame is
not present at the sensor, the flame control module will
close the Gas Valve. The Integrated Furnace Control will
then recycle the ignition sequence, then if ignition is not
achieved, it will shut off the Gas Valve and lock out the
system.
3. POWER FAILURE
If there is a power failure during a heating cycle, the
system will restart the ignition sequence automatically
when power is restored, if the Comfort Control still calls
for heat.
4. GAS SUPPLY FAILURE
If loss of flame occurs during a heating cycle, the system
Integrated Control Module will recycle the ignition sequence,
then if ignition is not achieved, the Integrated Control
Module will shut off the Gas Valve and lock out the system.
5. INDUCED DRAFT BLOWER FAILURE
Please refer to the Variable Speed Draft Inducer
troubleshooting manual for diagnostic assistance.
6. CONDENSATE DRAIN BLOCKAGE
If the condensate drain is blocked, either by debris,
improper draining, or by freezing condensate, the pres-
sure switch will receive a signal warning of the accumula-
tion of condensate in the heat exchanger assembly. The
pressure switch contacts will open and remain open, not
allowing unit operation. The unit will not operate until
the condensate drain has been cleared, and the conden-
sate flows freely.
7. RESET AFTER LOCKOUT
When the Integrated Furnace Control has shut the
system down and gone into lockout, the system must be
manually reset before the unit will restart. The system
can be reset by turning the system power off for more
than 1 second, or by removing 24VAC from the control for
more than 1 second, or by removing the Comfort Control
call for heat for more than 1 second but less than 20
seconds.
8. RESET AFTER BURNER BOX LIMIT SHUTDOWN
If the furnace shuts down, one thing that can be checked
is the burner box temperature limit switch. It is located
on the bottom of the burner box. The vent and combus-
tion air inlet terminations should be checked for block-
age. If blockage exists, clear the problem and then the
reset button may be depressed. If there is no blockage
of the terminations, the limit switch must be reset
by a qualified servicer.
INDOOR MOTOR MAINTENANCE
Direct drive motors have bearings which are permanently
lubricated and under normal use, lubrication is not recom-
mended.
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