Sequence Of Operation; Self-Test Mode; Heating Mode - Carrier 58MVP080 Installation, Start-Up, And Operating Instructions Manual

32°F MINIMUM INSTALLED
AMBIENT OR FREEZE
PROTECTION REQUIRED
Unit must not be installed, operated, and then turned and left
off in an unoccupied structure during cold weather when
temperature drops to 32°F or below unless drain trap and
drain line have adequate freeze protection. See Service and
Maintenance Instructions for winterizing procedure.
OPEN STAND
PIPE FOR
A/C OR
HUMIDIFIER
DRAIN
TEE
TO OPEN
DRAIN
Fig. 41—Example of Field Drain Attachment
3. Use wire ties to secure heat tape in place. Wire ties can be
positioned in notches of condensate trap sides. (See Fig. 42.)
4. Wrap field drain pipe with remaining heat tape, approximately
1 wrap per ft.
5. When using field-supplied heat tape, follow heat tape manu-
facturer's instructions for all other installation guidelines.
CONDENSATE TRAP
WIRE TIE(S)
HEAT TAPE
(3 WRAPS MINIMUM)
Fig. 42—Condensate Trap Heat Tape
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Furnace control must be grounded for proper operation, or
control will lock out. Control is grounded through green wire
routed to gas valve and burner box screw.
Using schematic diagram (see Fig. 23), follow sequence of
operation through different modes. This furnace has a new control
system. Read and follow wiring diagram carefully.
NOTE: If 115-v power supply to furnace or 24-v blower access
panel switch is interrupted during a call for heat, blower operates
for 60 sec when power is restored before heating cycle is resumed.
Step 1—Self-Test Mode
The control center goes through a brief self-test whenever the
115-v or 24-v power is interrupted. The self-test takes approxi-
mately 2 sec to complete. After power is restored, the red
(microprocessor) LED briefly comes on. Then the green LED
comes on for 1 sec, followed by 1 sec where both the yellow and
green LED's are lit. During this time, the microprocessor is
checking itself.
Step 2—Heating Mode
When the thermostat "calls for heat," R-W/W1 circuit closes.
1. Prepurge period—The inducer motor is turned on and slowly
comes up to speed. When the low-pressure switch closes, the
inducer motor RPM is noted by the microprocessor, and a 25
sec prepurge period begins. The RPM is used to evaluate the
vent system resistance. This evaluation is then used to
determine the required RPM necessary to operate the inducer
in high- or low-heat modes.
NOTE: The heat cycle can start in either high or low heat. If a
high-heat cycle is initiated, the inducer continues increasing its
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speed until the high-pressure switch closes before the 25 sec
prepurge period begins.
2. Humidifier (HUM)—The HUM terminal is energized when-
ever the inducer prepurge period is completed.
3. Ignitor warm up—At end of prepurge period, the hot surface
ignitor (HSI) is energized for a 17-sec HSI warm-up period.
4. Ignition sequence—After the HSI ignitor warm-up period is
completed, gas valve opens, permitting gas flow to burners
where it is ignited. After 5 sec, the HSI is de-energized and a
2-sec flame-sensing period begins.
29

SEQUENCE OF OPERATION

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