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107273-UUM-C-0306
SECTION V: SERVICE AND MAINTENANCE
MANUAL
SAFETY SECTION
This section has been designed to assist a qualified service agency in
performing service and maintenance on this appliance. The homeown-
ers and/or end user must never attempt to perform any service or main-
tenance on the appliance especially when it involves the removal or
adjustment of any parts and/or components.
The following safety rules must be followed when servicing the
furnace.
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-
nace.
• When servicing controls, label all wires prior to discon-
necting. Reconnect wires correctly.
• Verify proper operation after servicing.
FURNACE MAINTENANCE
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 screen (if applicable).
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.
FURNACE CLEANING
NOTE: The cleaning operations listed below must be performed only by
a qualified service agency.
Burner Removal/Cleaning
The main burner 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 upper access panel.
4.
Disconnect wires from flame sensor, rollout switch and direct spark
igniter (DSI). Remove igniter carefully, as it is easily broken.
5.
Remove the screws that hold the burner box assembly to the ves-
tibule panel and remove the assembly.
6.
Remove burners from the burner assembly.
7.
Rinsing in hot water may clean burners.
8.
Reassemble in the reverse order.
20
Cleaning the Heat Exchanger
NOTE: It is recommended that replacement gaskets be available
before removing vent motor.
Lower Heat Exchanger Access
1.
Turn off the electrical power to the unit and turn off gas supply at
the shut-off valve.
2.
Remove the blower and burner compartment access doors. Dis-
connect the gas supply piping at the union to permit removal of the
entire burner and gas control assembly from the vestibule panel.
Use the wrench boss on the gas valve when removing or installing
this piping. Refer to Figure 18.
3.
Unplug the black and white line voltage wires at the quick connec-
tor terminals. Identify and note the location of all leads for ease of
reinstallation.
4.
Unplug the red and black wires that are connected to the T & T
terminals on the primary control. These wires can be disconnected
at the quick connect terminals.
5.
Remove the screws securing the chamber to the vestibule panel
and very carefully remove it.
6.
Remove the screws holding the burner assembly to the vestibule
panel and remove this assembly. Handle the assembly carefully
since it contains the igniter, which is fragile and easily broken. The
lower portion of the heat exchanger will now be exposed. Remove
any soot and scale. Vacuum loose soot, scale and dirt from the
heat exchanger.
7.
After cleaning is complete, replace all components in reverse
order. Re-gasket all surfaces which required a gasket. Reconnect
all wiring. Reattach vent pipe and gas supply lines before restoring
service to furnace. Restore electrical power, check gas supply pip-
ing for leaks, and then verify furnace operation.
U
Label all wires prior to disconnection when servicing con-
trols. Wiring errors can cause improper and dangerous
operation. Verify proper operation after servicing.
THE FURNACE CONTROLS AND THEIR FUNCTION
1.
Limit Control - This furnace is protected by two (2) high tempera-
ture limit switches. The lower limit switch is an automatic reset
type.
2.
Upper Limit Control - The upper limit switch near left side of
blower is a manual reset type limit switch. If burner does not func-
tion, turn system switch to "OFF" and push reset button in center
of limit switch.
3.
Gas Valve - The gas valve is 100% shut-off type and will fail safe if
for some reason the gas is turned off or the pilot goes out. It is also
of the step-open type which means they open to a low fire position
and after a few seconds step-open to high fire.
4.
Fan Switch - Turns the blower on upon temperature increase in
the heat exchanger compartment and turns blower off when heat
exchanger compartment temperature is below 90°.
Unitary Products Group
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