035-17438-001 Rev. A (901)
Unitary Products Group
21
Hot Surface Ignition System
MAINTENANCE
Air Filters
The filters should be checked periodically for dirt accumula-
tion. Dirty filters greatly restrict the flow of air and overburden
the system.
Clean the filters at least every three months. On new con-
struction, check the filters every week for the first four weeks.
Inspect the filters every three weeks after that, especially if
the system is running constantly.
All filters used with the furnace are the high velocity, clean-
able type. Clean these filters by washing in warm water.
Make sure to shake all the water out of the filter and have it
reasonably dry before installing it in the furnace. When
replacing filters, be sure to use the same size and type as
originally supplied.
Upflow Filter Removal and Replacement
1.
Turn off electrical power supply to the furnace at discon-
nect switch. Remove access doors.
2.
In the blower compartment disengage the looped end of
the filter retainer wire from the front edge of the cabinet.
The wire will now pivot on the hinged ends at the rear of
the cabinet. Refer to Figure 3 on page 9.
3.
Remove the filter and follow the cleaning instructions
above. DO NOT remove the filter stiffener rods, if pro-
vided.
4.
When reinstalling the filter, be sure the filter completely
covers the cabinet opening and is secured in place by
the wire retainer.
Lubrication
Blower and ventor motors in these furnaces are permanently
lubricated and do not require periodic oiling.
BLOWER CARE
Even with good filters properly in place, blower wheels and
motors will become dust laden after long months of operation.
The entire blower assembly should be inspected annually. If
the motor and wheel are heavily coated with dust, they can
be brushed and cleaned with a vacuum cleaner.
The procedure for removing the direct drive blower assembly
for cleaning is as follows:
Upflow Blower Removal/Cleaning
The procedure for removing the variable speed blower
assembly for cleaning is as follows:
1.
Disconnect the power supplied to the furnace.
2.
Remove the vest and blower panels.
3.
Disconnect the motor control harness and the power har-
ness from the motor.
4.
Remove the 2 screws fastening the electrical panel to
the blower housing, remove the panel from the blower
housing and swing the assembly out of the way.
5.
Disconnect the auxiliary switch harness from the
switches.
6.
Remove the 5 blower assembly mounting screws and
pull the blower assembly forward and out of the slots in
the deck.
7.
Clean and or service the blower assembly being careful
not to remove tor relocate the balance clips on the
blower wheel.
8.
To reassemble, reverse the procedure, restore power to
the furnace and verify operation.
9.
Two vertical screws do not need to be reinstalled.
NOTE:
DO NOT Remove or Relocate the Balance Clips
on the blower wheel when cleaning the blower assembly.
An unbalanced wheel will cause noise and vibrations.
Burner and Flame Sensor 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 and turn off gas
supply at the shutoff valve.
2.
Remove the blower and burner compartment access
doors.
3.
Unplug ignitor from the wire harness and remove the
ignitor/bracket assembly from the burner air shield. Han-
dle the ignitor carefully as it is fragile and easily broken.
4.
Note the location and then disconnect the sensor and
rollout switch wires located on the top of the air shield
and remove the shield.
5.
Remove the two screws securing each burner to the
burner assembly. Note the orientation of the burner
(flanged side down) before removing. Burners may be
cleaned by rinsing in hot water or by using a vacuum
cleaner.
6.
Remove the retaining screw to the flame sensor and
remove the sensor from the burner box. Clean the flame
sense rod with steel wool and replace.
Do not attempt to light this furnace by hand (with a
match or any other means). There may be a poten-
tial shock hazard from the components of the hot
surface ignition system. The furnace can only be lit
automatically by its hot surface ignition system.
