73
A11273
Fig. 68 -- Cleaning Heat Exchanger Cell
2. Remove control door.
3. Disconnect wires or connectors to flame rollout switch, gas
valve, igniter, and flame sensor.
4. Using backup wrench, disconnect gas supply pipe from fur-
nace gas control valve.
5. Remove two screws attaching top filler plate and rotate up-
wards to gain access to screws attaching burner assembly to
cell panel.
6. Remove screws attaching burner assembly to cell panel.
See Fig. 65.
NOTE:
Burner cover, manifold, gas valve, and burner assembly
should be removed as one assembly.
7. Clean heat exchanger openings with a vacuum and a soft
brush. See Fig. 68.
NOTE
: After cleaning, inspect the heat exchangers to ensure they
are free of all foreign objects that may restrict flow of combustion
products.
8. Reverse items 6 through 1 for reassembly.
9. Refer to furnace wiring diagram and reconnect wires to
flame rollout switch, gas valve, igniter, and flame sensor.
10. Turn on gas and electrical supplies to furnace.
11. Check furnace operation through 2 complete heat operating
cycles. Look at burners. Burner flames should be clear blue,
almost transparent. See Fig. 61.
12. Check for gas leaks.
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
Never purge a gas line into a combustion chamber. Never
test for gas leaks with an open flame. Use a commercially
available soap solution made specifically for the detection
of leaks to check all connections. A fire or explosion may
result causing property damage, personal injury or loss of
life.
!
WARNING
13. Replace main furnace door.
Secondary Heat Exchangers
The condensing side (inside) of the secondary heat exchanger
CANNOT be serviced or inspected without complete removal of
the heat exchanger assembly. Detailed information on heat
exchanger removal can be obtained from your Distributor.
WINTERIZATION
UNIT AND PROPERTY DAMAGE HAZARD
Failure to follow this caution may result in unit component or
property damage.
If the furnace is installed in an unconditioned space where the
ambient temperatures may be 32
_
F (0
_
C) or lower, freeze
protection measures must be taken to prevent minor property
or product damage.
CAUTION
!
Since the furnace uses a condensing heat exchanger, some water
will accumulate in the unit as a result of the heat transfer process.
Therefore, once it has been operated, it cannot be turned off and
left off for an extended period of time when temperatures will
reach 32
_
F (0
_
C) or lower unless winterized. Follow these
procedures to winterize your furnace:
UNIT COMPONENT DAMAGE HAZARD
Failure to follow this caution may result in damage to the
furnace and other property damage.
Do not use ethylene glycol (automotive antifreeze coolant or
equivalent). Failure of plastic components may occur.
CAUTION
!
1. Obtain propylene glycol (RV/swimming pool antifreeze or
equivalent).
2. Turn off gas and electrical supplies to your furnace.
3. Remove furnace control door.
4. Remove the top unused rubber plug from the port on the
collector box opposite the condensate trap. See Fig 58.
5. Connect a field supplied 3/8--in. (9.5--mm) ID tube to the
open port on the collector box.
6. Insert a field supplied funnel into the tube.
7. Pour one quart (liter) of anti--freeze solution into the funnel/
tube. Antifreeze should run through the inducer housing,
overfill condensate trap and flow to an open drain.
8. Replace the rubber plug in the port on the collector box.
9. Remove the middle unused rubber plug from the port on the
collector box opposite the condensate trap. See Fig. 58.
10. Repeat Steps 5 through 8.
11. If a condensate pump is used, check with pump manufacturer
to verify pump is safe for use with antifreeze used. Allow
pump to start and pump anti--freeze to open drain.
12. Replace main door.
13. When furnace is re--started, flush condensate pump with clear
water to check for proper operation before re--starting furnace.
14. Propylene glycol need not be removed before re--starting
furnace.
SEQUENCE OF OPERATION
NOTE
: Furnace control must be grounded for proper operation or
control will lock out. Control is grounded through green/yellow
wire routed to gas valve and manifold bracket screw. Using the
schematic diagram in Fig. 70, follow the sequence of operation
through the different modes. Read and follow the wiring diagram
very carefully.
NOTE
: If a power interruption occurs during a call for heat (W),
the control will start a 90--sec blower--only ON period two sec after
power is restored, if the thermostat is still calling for gas heating.
The Amber LED light will flash code 12 during the 90--sec period,
after which the LED will be ON continuous, as long as no faults
