035-17468-001 Rev. A (801)
34
Unitary Products Group
SINGLE STAGE THERMOSTAT
If a single stage thermostat is used the unit will be controlled
through the CFM Timer board timer adjustment pins (Refer to
Figure 13 on Page 13.). For the furnace to operate on High
Fire the timer jumper must be placed on the 10, 15 or 20
minute adjustment terminals. On a call for heat the unit will
operate on low fire as detailed above. If the heating require-
ments cause the cycle to exceed the jumper settings, the
high fire timer will energize the second stage heat. The sec-
ond stage operation will function as detailed above. The heat-
ing cycle will be completed in high fire operation. If the timer
jumper is in the “TIME OFF” position with a single-stage ther-
mostat, the unit will stay in low fire operation.
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 4 on Page 8)
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:
1.
Disconnect the electrical supply to the furnace and
remove the access doors.
2.
Remove blower assembly mounting screws and slide the
blower assembly out of the slots in the deck. If the two
shipping screws were not previously removed, also
remove and discard these two screws located on each
front corner of the blower assembly.
3.
To reassemble, reverse the procedure, restore power to
the furnace and verify operation.
BURNER AND FLAME SENSOR REMOVAL/CLEANING
The main burners and flame sensor should be checked peri-
odically for dirt accumulation or oxidation.
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.
8.
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.
Label all wires prior to disconnecting when servicing
controls. Wiring errors can cause improper and dan-
gerous operation. Verify proper operation after ser-
vicing.