Bryant 542J Series, Инструкция по установке, запуску и обслуживанию

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On a drop in room temperature, heating contact no. 1 in the
thermostat closes, energizing heat relay (HR), reversing valve
relay (RVR), reversing valve solenoids (RVS1 and RVS2) and
compressor (size 150) or compressor no. 2 (size 180) con-
tactor. Compressor (size 150) or compressor no. 2 (size 180)
and indoor and outdoor-fan motors start. If the 5-minute CTD
(compressor time delay) on the DB (defrost board) is satis-
fied, then compressor no. 1 contactor is energized and com-
pressor no. 1 (size 180) will start.
On units equipped with electric heat, when additional heat
is needed, heating contactor no. 2 in the thermostat closes,
energizing W2.
Units With Economizer
With unit main power on, set thermostat at HEAT position
and desired room temperature. Set fan switch at AUTO. (on
demand) or ON (continuous) position.
On a drop in room temperature, heating contact no. 1 in the
thermostat closes, energizing heat relay (HR), reversing valve
relay (RVR), reversing valve solenoids (RVS1 and RVS2) and
compressor no. 2 contactor. Compressor no. 2 (size 180) and
indoor and outdoor fan motors start. If the 5-minute CTD (com-
pressor time delay) on the DB (defrost board) is satisfied, then
compressor (size 150) or compressor no. 1 (size 180) con-
tactor is energized and compressor (size 150) or compressor
no. 1 (size 180) will start. The outdoor-air damper stays at
vent position while the indoor fan is operating.
On units equipped with electric heat, when additional heat
is needed, heating contactor no. 2 in the thermostat closes,
energizing W2.
C. Defrost Cycle
When the temperature of the outdoor coil drops below 28 F
as sensed by the defrost thermostat (DFT1 or DFT2), the de-
frost timer starts. At the end of a timed period (factory set at
30 minutes or field-adjusted to 50 or 90 minutes), the defrost
cycle will begin. The defrost board energizes terminals O and
W2, energizes the defrost relay (DR), deenergizes the revers-
ing valve solenoids (RVS1 and RVS2), and energizes the elec-
tric heat. The outdoor-fan motor will stop.
The unit continues to defrost either until the coil tempera-
ture as measured by DFT1 or DFT2 reaches 65 F, or until
unit completes a 10-minute defrost cycle.
During the defrost mode when a circuit defrosts, RVS will os-
cillate between heating and cooling modes until defrost mode
is complete. This will prevent the head pressure from getting
too high.
At the end of the defrost cycle, the electric heater(s) (if ap-
plicable) will be deenergized, the reversing valve solenoids
will be energized, and the outdoor fans will start.
A freeze protection thermostat (FPT) is located on the indoor
coil. It detects frost buildup and turns off the compressor(s),
allowing the coil to clear. Once frost has melted, the compres-
sor can be reenergized.
D. Automatic Changeover
When the system selection switch is set at AUTO. position,
unit automatically changes from heating operation to cooling
operation when the temperature of the conditioned space rises
to the cooling lever setting. When the temperature of the con-
ditioned space falls to the heating lever setting, unit auto-
matically changes from cooling to heating operation (with a
3 F deadband in between).
E. Continuous Air Circulation
Turn unit power on. Set system control at OFF position. Set
fan switch at ON position. The indoor-fan contactor is ener-
gized through the thermostat switch and the indoor fan runs
continuously.
F. Anti-Short Cycle Protection
If unit operation is interrupted by an open high-pressure switch,
low-pressure switch, indoor coil freezestat, or by compressor
internal line-break device (overcurrent or overtemperature),
and compressor is calling for either cooling or heating, anti-
short cycle protection device simultaneously locks out unit
and lights a warning light on the thermostat. Restart the unit
by manually turning thermostat to OFF and then to ON po-
sition. If any of the protective devices opens again, the unit
continues to lock out until corrective action is taken.
NOTE:
If the unit fails to operate due to compressor overcur-
rent condition, restart by manually resetting circuit break-
ers at the unit. Restart cannot be accomplished at the room
thermostat.
G. Emergency Heat
If compressor is inoperative due to a tripped safety device
(high or low pressure, indoor coil freezestat, overcurrent, or
overtemperature), the anti-short cycle device locks out the com-
pressor and lights a warning light on the room thermostat.
When the switch is on (thermostat is set to the EM HT po-
sition), compressor circuit and outdoor thermostats are by-
passed, and the second stage of thermostat energizes the in-
door blower and the electric resistance heater.
H. Safety Check of Limit Control
A manual-reset limit control is located on the indoor-air blower.
The control shuts off the unit in the event of fan failure.
II. COOLING SECTION START-UP AND ADJUSTMENTS
CAUTION: Complete the required procedures given
in the Pre-Start-Up section on page 13 and the Start-Up
Checklist on page CL-1 before starting the unit.
Do not jumper any safety devices when operating the
unit.
Do not operate the compressor when the outdoor tem-
perature is below 40 F (unless accessory low ambient
kit is installed).
Do not rapid-cycle the compressor. Allow 5 minutes be-
tween ‘‘on’’ cycles to prevent compressor damage.
A. Checking Cooling Control Operation
Start and check the unit for proper cooling control operation
as follows:
1. Place room thermostat SYSTEM switch in OFF posi-
tion. Observe that blower motor starts when FAN switch
is placed in ON position and shuts down when FAN switch
is placed in AUTO. position.
2. Place SYSTEM switch in COOL position and FAN switch
in AUTO. position. Set cooling control below room
temperature. Observe that compressor, outdoor fan
motor, and indoor blower motors start. Observe
that cooling cycle shuts down when control setting is
satisfied.
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