035-17477-002 Rev. D (1202)
36
Unitary Products Group
BURNER REMOVAL/CLEANING
The main burners should be checked periodically for dirt
accumulation.
If cleaning is required, follow this procedure:
1.
Turn off the electrical power to the unit.
2.
Turn off the gas supply at the external manual shutoff
valve and loosen the ground union joint.
3.
Remove the upper access panel and remove the burner
box cover.
4.
Remove the screws that hold the burner box assembly to
the vest panel and remove the assembly.
5.
Remove burners from the burner assembly.
6.
Burners may be cleaned by rinsing in hot water.
7.
Reassemble the burners in the reverse order.
CLEANING THE HEAT EXCHANGER
1.
Turn off the main manual gas valve external to the
furnace.
2.
Turn off electrical power to the furnace.
3.
Remove the upper access panel and remove the burner
box cover.
4.
Disconnect wires from flame sensor, rollout switch and
HSI igniter. Remove igniter carefully, as it is easily
broken.
5.
Remove the screws that hold the burner box assembly to
the vestibule panel and remove the assembly. The upper
portion of the heat exchanger will now be exposed.
6.
Remove the upper cover plate at the top of the furnace.
Remove the internal baffle.
7.
The upper portion of the heat exchanger is now
exposed.
8.
With a long flexible wire brush, clean inside each tube at
both the top and bottom. The brush must pass around
the rear heat exchanger tubes. Vacuum loose scale and
dirt from each tube.
9.
Clean - vacuum all burners.
10. Replace all components in reverse order. Reconnect all
wiring.
11. Restore electrical power and gas supply to the furnace.
12. Check furnace operation.
CLEANING THE SECONDARY HEAT EXCHANGER
1.
Follow steps 1 thru 10 under Cleaning the Primary Heat
Exchanger.
2.
Remove the vent piping from the venter housing. Discon-
nect the drain lines from the venter and from the conden-
sate drain pan. Remove the venter blower and the
condensate pan. The turbulators can then be gently
removed from the secondary heat exchanger.
3.
With a stiff wire brush, brush out loose scale or soot.
4.
Vacuum the secondary heat exchanger.
5.
Finish the cleaning procedure by following steps 10 thru
12 under Cleaning the Primary Heat Exchanger.
VENT/AIR INTAKE
Should it be necessary to service the vent/air intake system,
the manufacturer recommends this service be conducted by
a qualified service agency.
The operation of this appliance requires the reassembly and
resealing of the vent/air intake system as specified on Page
11.
TROUBLESHOOTING
The following visual checks should be made before trouble-
shooting:
1.
Check to see that the power to the furnace and the igni-
tion control module is ON.
2.
The manual shutoff valves in the gas line to the furnace
must be open.
3.
Make sure all wiring connections are secure.
4.
Review the sequence of operation.
Start the system by setting the thermostat above the room
temperature. Observe the system's response. Then use the
troubleshooting section in this manual to check the system's
operation.
FURNACE CONTROL DIAGNOSTICS
The furnace has built-in, self diagnostic capability. If a system
problem occurs, a fault code is shown by a blinking red LED.
It is located behind a clear view port in the blower compart-
ment door. DO NOT remove the furnace blower compartment
panel OR turn off furnace power as either action will clear the
control's memory of the fault.
The control continuously monitors its own operation and the
operation of the system. If a failure occurs, the LED will indi-
cate the failure code. If the failure is internal to the control, the
light will stay on continuously. In this case, the entire control
should be replaced as the control is not field repairable.
Flash sequence codes 1 through 11 are as follows: LED will
turn “on” for one second and “off” for one second. This pat-
tern will be repeated the number of times equal to the code.
For example, six “on” flashes equals a number 6 fault code.
All flash code sequences are broken by a 2 second “off”
period.
Label all wires prior to disconnection when servic-
ing controls. Wiring errors can cause improper and
dangerous operation. Verify proper operation after
servicing.
