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

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3. When using an autochangeover room thermostat, place
both SYSTEM and FAN switches in AUTO. position.
Observe that unit operates in heating mode when tem-
perature control is set above room temperature and
operates in cooling mode when temperature control is
set below room temperature.
B. Checking and Adjusting Refrigerant Charge
The factory charge is the correct amount for the best perfor-
mance; however, this charge may require a slight adjust-
ment to attain rated performance.
The size 150 units have one refrigeration circuit and the size
180 units have 2 separate refrigeration circuits. Each circuit
must be charged separately (size 180). The unit must be op-
erating in the second stage of cooling when charging with re-
frigerant. See Refrigerant Charge section on page 23 for more
details.
C. Refrigerant Leaks
Proceed as follows to repair a refrigerant leak and to charge
the unit:
1. Locate leak and ensure that refrigerant has been
recovered.
2. Repair leak following accepted practices.
NOTE: Install a new filter drier whenever the system has
been opened for repair.
3. Add a small charge of R-22 refrigerant vapor to system
and leak-test unit.
4. Recover refrigerant and evacuate system if additional
leaks are not found.
5. Charge unit with R-22 refrigerant, using a volumetric-
charging cylinder or accurate scale. Refer to unit rating
plate for required charge. Be sure to add extra refrig-
erant to compensate for internal volume of filter drier.
D. Cooling Sequence of Operation
Units Without Economizer
With unit main power on, set thermostat to COOL position
and desired room temperature. Set fan switch at AUTO. (on
demand) or ON (continuous) position.
On a rise in room temperature, cooling contact no. 1 in the
thermostat closes. The indoor and outdoor fan motors start.
If the 5-minute compressor time-delay (CTD) on the defrost
board (DB) is satisfied, then compressor no. 1 contactor is en-
ergized and compressor no. 1 will start. Compressor no. 1 cycles
on demand of the thermostat to satisfy room conditions. Each
time the cooling contactor no. 1 opens, the CTD starts the
5-minute delay.
On size 180 units, with an additional rise in room tempera-
ture, cooling contactor no. 2 in the thermostat closes, ener-
gizing compressor contactor no. 2. Compressor no. 2 starts
and cycles on demand of the thermostat to satisfy the occu-
pied space demands.
Units With Economizer
Upon a call for cooling, when outdoor ambient temperature
is above the temperature control setting, the indoor and out-
door fans and compressor(s) energize. The economizer damper
moves to vent position.
Upon a first-stage call for cooling, when outdoor ambient tem-
perature is below the temperature control setting, the indoor
fan starts and economizer damper modulates to maintain mixed-
air temperature. The compressor(s) remains off.
Upon a second-stage call for cooling, compressor no. 1
(size 180) or unloaded compressor (size 150) is energized and
mechanical cooling is integrated with economizer cooling. Com-
pressor no. 2 (size 180) is locked out. If the air temperature
is below 50 F, a cooling lockout switch prevents the compres-
sor(s) from running.
When supply-air temperature drops below a fixed set point,
the economizer damper modulates to maintain the tempera-
ture at the fixed set point.
III. INDOOR AIRFLOW AND AIRFLOW ADJUSTMENTS
CAUTION:
For cooling operation, the recommended
airflow is 300 to 500 cfm per each 12,000 Btuh of rated
cooling capacity. For heating operation, the airflow must
produce a temperature rise that falls within the range
stamped on the unit rating plate.
Adjust indoor-fan speed to meet jobsite conditions. Refer to
Tables 5 and 6 to determine fan speed settings. See Table 7
for static pressure information pertaining to field-installed ac-
cessories and factory-installed options. See Table 8 for indoor-
fan motor performance details. See Fig. 23 and 24 for fan
performance using high static horizontal regain adapter and
power exhaust. See Table 9 for fan rpm pulley settings.
A. Indoor-Fan Performance Adjustment
CAUTION: Before performing service or mainte-
nance operations on unit, turn off main power switch
to unit. Electrical shock could cause personal injury.
To align fan and motor pulleys (See Fig. 25):
1. Loosen fan pulley setscrews.
2. Slide fan pulley along fan shaft.
3. Make angular alignment by loosening motor from mount-
ing plate.
B. Belt Tension Adjustment.
1. Loosen fan motor bolts.
2. a. Size 150 Units:
Move motor mounting plate up or down for proper
belt tension (
1
⁄
2
-in. deflection with one finger).
b. Size 180 Units:
Turn motor jacking bolt to move motor mounting plate
up or down for proper belt tension (
3 ⁄
8
-in. deflection
at midspan with one finger [9 lb force]).
3. Tighten pivot bolts.
4. Adjust bolts and nut on mounting plate to secure motor
in fixed position.
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