Heat Pipe Technology BKP 250, Установка, эксплуатация и обслуживание

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9
The outdoor condenser is powered from a separate power supply. No control voltage wiring is
connected. A head pressure switch inside the outdoor condenser controls the fan. The fan comes on
when the pressure in the outdoor coil reaches 240 psig and shuts off when it drops below 190 psig.
The refrigerant flows from the compressor to the reversing valve inlet. In the de-energized state the flow
is sent to the indoor condenser. The line going to the outdoor condenser is internally connected to the
reversing valve's center suction port, which is connected to the suction line coming out of the evaporator
by a 3/16" tube. This tube has a check valve installed in it. Any refrigerant in the outdoor condenser will
be pulled back through this 3/16" tube as the compressor runs. A check valve in the leaving liquid line of
the outdoor condenser prevents refrigerant from being pulled backward through the condenser coils.
When the reversing valve shifts to the outdoor condenser the indoor condenser is connected to the
suction by the 3/16" line. The indoor coil also has a check valve in the liquid line out.
The 3/16" line to the suction header provides a smoother transition when shifting. A hissing sound for 10
to 20 seconds is normal while the machine equalizes after shifting.
The BKP-AC
TM
also has a liquid receiver in the common liquid line.
If the BKP-AC
TM
is installed in an application where it may need to run in the winter when outdoor
temperatures will be below freezing, special provisions need to be made in the installation. An outdoor
thermostat must be installed to prevent the BKP-AC
TM
from shifting to the outdoor mode when
temperatures are below 50°F. If the unit is allowed to shift to the outdoor condenser when the
temperature is below that of the evaporator temperature, the compressor will not be able to pull the
refrigerant back when it shifts to the indoor coil and the unit will shut down on low pressure. A check
valve in the liquid line and in the small suction return line prevent refrigerant from migrating to the outdoor
coil during cold whether, while the unit operates in the Heating Mode.
9.2 OPTIONAL EQUIPMENT
9.21 Phase Loss Monitor for Three Phase Units
Units with a Phase loss monitor are provided with fuses which feed the phase loss monitor and the
control transformer. The monitor has an adjustable setting for operating voltage which determines the trip
settings.
This voltage must be set at startup to the measured line voltage . This monitor samples the
voltage between all three phases and closes a set of normally open contacts when the voltage and phase
rotation is correct A red LED lights up to indicate the contact is closed. The contact will open if line
voltage on any phase drops by 10% of the adjusted line voltage setting or an unbalance of 4% occurs
between phases. The contact will open to drop the 24 V control power to the control system.
9.22
Cooling Priority Relay
Units with a cooling priority relay will energize the BKP
TM
in the cooling mode on a call for cooling from the
thermostat even if the dehumidistat is satisfied. Control voltage from the thermostat to the reversing valve
is used to energize the cooling relay. Normally open contacts 2 and 4 close to supply control power
directly from the transformer to the yellow wire coming from the dehumidistat. When the thermostat is
satisfied, the BKP
TM
will shut down again.