Carrier WEATHERMAKER 8000 58WAV - Manual (Page 8)

24-V WIRING — Make field 24-v connections at the 24-v tenni-
nal strip. (See Fig. 9.) Connect terminal Y as shown in Fig. 8 for
proper cooling operation. Use only AWG No. 18, color coded
copper thermostat wire.
The 24-v circuit contains an automotive-type, 3-amp fuse located
on the main control board. Any direct shorts during installation,
service, or maintenance could cause this fuse to blow. If fuse
replacement is required, use ONLY a 3-amp fuse of identical size.
ACCESSORIES
1. Electronic Air Cleaner (EAC)
Two screw terminals (EAC-1 and EAC-2) are provided for
EAC connection. The terminals are energized with 115-v,
1-amp maximum during blower motor operation.
2. Humidifier (HUM)
Screw terminals (HUM-1 and C) are provided for 24-v
humidifier connection. The terminals are energized with 24-v,
0.5-amp maximum during heating blower motor operation.
Step 7— Venting
Refer to the enclosed Installation Instructions, GAMA Venting
Tables for Category I Furnaces, and QUIK'VENT™ Tables for
Category I Fan-Assisted Furnaces. The horizontal portion of the
venting system shall maintain a minimum of 1/4-in. upward slope
per linear ft and it shall be rigidly supported every 5 ft or less with
hangers or straps to ensure that there will be no movement after
installation.
Step 8—Start-Up, Adjustment, and Safety Check
GENERAL — The furnace must have a 115-v power supply
properly connected and grounded. Proper polarity must be main­
tained for correct operation. Thermostat wire connections at R, W,
C, and Y must be made at the 24-v terminal block on the control
board. The gas service pressure must not exceed 0.5 psig (14-in.
wc), but must be no less than 0.16 psig (4.5-in. wc).
A CAUTION
This furnace is equipped with a manual reset limit switch in
the gas control area. The switch opens and shuts off power to
the gas valve if a flame rollout or over heating condition
occurs in the gas control area. DO NOT bypass the switch.
Correct inadequate combustion air supply problem and reset
the switch.
Before operating the furnace, check each manual reset switch for
continuity. If necessary, press the button to reset the switch.
The blower compartment door must be in place to complete the
115-v circuit to the furnace.
SEOUENCE OF OPERATION — Using the schematic diagram
shown in Fig. 10, follow the sequence of operation through the
different modes. Read and follow the wiring diagram very care­
fully.
NOTE:
If there is a power interruption on any thermostat call, the
control initiates a 90-sec blower only on period before starting
another cycle.
1. Heating mode
When the wall thermostat "calls for heat," the R-W circuit
closes. The furnace control performs a self-check, verifies the
pressure switch contacts are open, and starts the inducer
motor.
a. Prepurge period—As the inducer motor comes up to speed,
the pressure switch contacts close to begin a 15-sec
prepurge period.
b. Ignitor warm-up—At the end of the prepurge period, the
ignitor is energized for a 17-sec ignitor warm-up period. If
ignition is not established during the first cycle, the next
warm-up period is increased to 45 sec. All subsequent
ignition cycles will be 45 sec, or until the 115-v power
supply is interrupted. By interrupting the 115-v power
supply, the warm-up period is automatically reset to 17 sec.
c. Ignition sequence—When the ignitor warm-up period is
completed, the gas valve opens, permitting gas flow to the
burners where it is ignited. After 5 sec, the ignitor is
de-energized and a 2-sec flame-sensing period begins.
d. Flame-sensing—When burner flame is sensed, the control
begins the blower on delay period and continues holding
the gas valve open. If burner flame is not sensed, the
control closes the gas valve and repeats ignition cycle.
e. Blower on delay—Forty sec after burner flame is proven,
the blower motor is energized on heating speed. Simulta­
neously, the humidifier and electronic air cleaner terminals
(HUM-1 and C for humidifier, EAC-1 and EAC-2 for
electronic air cleaner) are energized. Jumper JW9
SHOULD NOT be cut. If jumper JW9 has been cut, the
blower on delay will be 60 sec.
f. Blower off delay—When the thermostat is satisfied, the
circuit between R-W is broken, de-energizing the gas valve
and stopping gas flow to the burners. The blower motor,
humidifier, and air cleaner remain energized 90, 135, 180,
or 225 sec (depending on the blower off time selection).
The furnace is factory set for a 135-sec blower off delay.
g. Post-purge period —The inducer motor remains energized
5 sec after the burners are extinguished. Jumper JW9
should not be cut. If jumper JW9 has been cut, the
post-purge period is 15 sec.
2. Cooling mode
When the thermostat "calls for cooling" R-Y circuit closes.
The R-Y circuit starts the outdoor condensing unit and starts
the furnace blower motor on cooling speed. The EAC termi­
nals are energized with 115v when the blower is operating on
cooling speed.
When the thermostat is satisfied, R-Y circuit is broken. The
condensing unit stops and the furnace blower continues
operating on cooling speed for an additional 90 sec.
3. Continuous blower mode
When the R-G circuit is made, the blower motor operates on
heating speed. During a "call for heat" the blower stops,
f
allowing the furnace heat exchangers to heat up more quickly,
then restarts at the end of the 40 sec blower on delay period.
Jumper JW9 should not be cut. If jumper JW9 has been cut,
the blower on delay will be 60 sec.
The blower reverts to continuous operation after the heating
cycle is completed.
When the thermostat "calls for cooling," the blower operates
on cooling speed. When the thermostat is satisfied, the blower
operates an additional 90 sec before reverting back to con­
tinuous operation on heating speed. EAC and HUM-1 termi­
nals are energized.
4. Heat pump mode
When installed with a heat pump, the furnace control auto­
matically changes the timing sequence to avoid long blower
off time during demand defrost cycles. When the W-Y or
W-Y-G thermostat inputs are received at the same time, the
control changes the blower to heating speed or starts the
blower if it was off, and begins a heating cycle. The blower
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