Sequence Of Operation; Troubleshooting; Safety Section; Burner Removal/Cleaning - Coleman 268897-UUM-B User Manual

268897-UUM-B-1108
SECTION Ih SERVICE AND MAINTENANCE
MANUAL
SAFETY SECTION
The following safety rules must be followed when servicing the
furnace.
,WARNING
ELECTRIC SHOCK, FIRE OR EXPLOSION HAZARD
Failure to follow safety warnings exactly could result in
dangerous operation, serious injury, death or property
damage.
Improper servicing could result in dangerous operation,
serious injury, and death or property damage.
Before servicing, disconnect all electrical power to the fur-
Race.
When servicing controls, label all wires prior to disconnect-
ing. Reconnect wires correctly.
Verify proper operation after servicing.
FURNACE MAINTENANCE SECTION
The furnace should be cleaned and adjusted by a certified dealer or
qualified service contractor once a year or before the start of every
heating season. The following items must be cleaned and serviced or
replaced if there are signs of deterioration.
1. The vent terminal.
2. The furnace vent and combustion air intake passageways. Should
it be necessary to service the vent/air intake system, the manufac-
turer 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.
3. The furnace burners, ignitor and flame sensor.
4. The condensate collection and disposal system. If any disassem-
bly of components containing flue or vent gases is required, a
qualified service agency must perform the service.
FURNACE CLEANING SECTION
NOTE: The cleaning operations listed below must be performed only by
a qualified service agency.
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 shut-off valve and
loosen the ground union joint.
3. Remove the burner door 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 vest
panel and remove the assembly.
6. Remove burners from the burner assembly.
7. Burners may be cleaned by rinsing in hot water.
8. Reassemble the burners in the reverse order.
Cleaning the Heat Exchanger
1. Turn off the electrical power to the unit.
2. Turn off the gas supply at the external manual shut-off valve and
loosen the ground union joint.
3. Remove the burner door 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 vest
panel and remove the assembly.
6. Remove the vent pipe assembly, vent blower and condensate pan.
7. 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. Then vacuum loose the scale and dirt from each
tube.
9. Replace all components in reverse order. Reconnect all wiring.
10. Restore electrical power and gas supply to the furnace.
11. Check furnace operation.
CAUTION
Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and danger-
ous operation. Verify proper operation after servicing.
Cleaning the Secondary Heat Exchanger
1. Follow steps 1 - 7 under cleaning the Heat Exchanger.
2. Remove the vent piping from the vent blower housing. Disconnect
the drain lines from the vent blower housing and from the conden-
sate drain pan. Remove the vent blower housing blower and the
condensate pan.
3. Using a stiff wire brush, remove the loose scale or soot from each
tube.
4. Vacuum the secondary heat exchanger.
5. Finish the cleaning procedure by following steps 9 - 11 under
cleaning the Heat Exchanger.
TROUBLESHOOTING
The following visual checks should be made before troubleshooting:
1. Check to see that the power to the furnace and the ignition control
module is ON.
2. The manual shut-off 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.
AWARNING
Never bypass pressure switch to allow furnace opera-
tion. To do so will allow furnace to operate under poten-
tially hazardous conditions.
Do not try to repair controls. Replace defective controls
with UPG Source 1 Parts.
Never adjust pressure switch to allow furnace operation.
SEQUENCE OF OPERATION
The following describes the sequence of operation of the furnace. Refer
to Figure 1 for component location.
Continuous Blower
Cooling/heating thermostats have a fan switch that has an ON and
AUTO position. In the ON position the thermostat circuit is completed
between terminals R and G. The motor will operate on the speed tap
wire that is connected to the "HI COOL" cooling terminal on the control
board. To obtain a constant air circulation at lower flow rate, change the
high-speed wire to either the medium speed wire or the low speed wire.
Johnson Controls Unitary Products 5