Carrier 58DHL - Manual (Page 4)

hanger bolts (Four each %-in. all-thread rod) cut to desired
length, 1 X % flat washer, % lockwasher, and % nut. Dimples
are provided for hole locations. See Fig. 3.
NOTE:
Use Type B1 vent in a concealed space.
The crawl space installation is very similar to the attic;
therefore, refer to Division VI, Section B, steps 1, 2, and 3.
The installation of a sheet metal shield in front of the lou­
vered control panel is covered in step 4. For a crawl space
installation, this same sheet metal shield must be installed
above the louvered control panel. Extend the sheet metal
shield over the furnace top far enough to cover the gas pipe
entry hole.
VIII. FILTER ARRANGEMENT
The two factory-supplied filters are shipped in the blower
compeirtment. After the return-air duct has been connected
to the furnace, install the filters in a V-formation inside the
return-air plenum. See Fig. 10 and Table 5 for horizontal
applications. See Fig. 11 for downflow applications.
Fig. 10—Horizontal Filter Arrangement
Table 5—Filter Retainer
Furnace Casing Width D
14^,6 15=As
M'k
1472
21 13%6
2Vk
1274
IX. SEQUENCE OF OPERATION
Using the schematic wiring diagram. Fig. 12, trace the
sequence of operation for the heating cycle is as follows:
1. When the blower door is in place, 120 volts is supplied
through blower door interlock switch 9G. Transformer
lA is energized, supplying 24 volts to heating-blower
relay coil 2E, which opens normally closed blower relay
contacts 2E in the low-speed circuit of blower motor
3D.
2. The wall thermostat “calls for heat,” closing the R and
W circuit. This closed circuit supplies power to the 24-
volt safety circuit containing hmit switch 7H1, fusible
link lie, manual-reset draft-safeguard switch 7H2, and
manual reset auxfliary switch 7H3.
3. Simultaneously, the pilot solenoid coil of gas valve 5F,
spark generator 6F, and inducer-motor relay coU 2D
are energized. Inducer-motor relay contacts 2D in the
120-volt circuit close, starting inducer blower motor
INSTALLATION
POSITION
OF F
ilters
A82179
Fig. 11—Position of Filters
3A. Also, another set of contacts in inducer-motor
relay 2D close in the 24-volt circuit, and lock in
inducer-motor relay coil 2D. The coU is locked in until
the R and W circuit or safety circuit opens.
4. When the pilot solenoid coil of gas valve 5F is ener­
gized, gas flows to the pilot. The pressure switch
within the gas valve senses the pilot gas pressure and
closes. The pilot gas is ignited by a spark produced by
spark generator 6F. Simultaneously, inducer motor 3A
comes up to speed, actuating flow sensing switch 7V,
which supphes 24 volts to the hold circuit of gas valve
5F. After a short delay, the normally closed contacts of
the pilot-flame sensing switch 6H opens. The pilot sole­
noid cofl. remains energized through the hold circuit,
while the spark generator 6F shuts off within a few sec­
onds after ffame is sensed at the spark electrode. The
normally open pilot-flame sensing contacts close 5 to
20 seconds later, making the circuit to the MVG (Main
Operator) of gas valve 5F. Gas valve 5F opens 6 to 15
seconds later allowing gas flow to the meun burners,
which are ignited by pilot 6H. Simultaneously, time-
delay circuit IIL in the blower control center is ener­
gized. Approximately 50 seconds after gas valve 5F
opens, heating relay coil 2E is deenergized, which
closes the 120-volt contacts of heating relay 2E, start­
ing blower motor 3D on its heating speed.
5. When the thermostat is satisfied, the circuit between R
and W is broken, deenergizing gas valve 5F, inducer
motor relay 2D, and the solid-state time-delay circuit
on the printed-circuit board. The gas flow stops imme­
diately to the pilot and main burners. After approxi­
mately 105 seconds, heat relay 2E is energized and
blower motor 3D stops.
NOTE:
After a brief interruption of either electric or gas
supply, the furnace will not resume operation until the con­
tacts of pilot-flame sensing switch 6H move from the nor­
mally open to the normally closed position.
Cooling Cycle
1. The wall thermostat “calls for coohng.”
2. The R, G, and Y circuits are energized. Simultaneously,
the R-and-Y circuit starts the outdoor condensing unit,
and the R-and-G circuit energizes cooling relay coil 2F,
which closes normally open contacts 2F, energizing the
cooling speed winding of motor 3D and opening the
normally closed contacts of cooling relay 2F.
X. ELECTRICAL CONNECTIONS
A. Line-Voltage Wiring
IMPORTANT: Before proceeding with the electrical con­
nections, make certain that voltage, frequency, and phase