Heatcraft Refrigeration Products II - Manual (Page 15)

15
Beacon II Controller
Refrigerant Line Brazing ( CAUTION )
The electric expansion valve and the suction temperature sensor on the suction line are factory installed.
Care must be taken when brazing these lines at the evaporator.
Too high a temperature may destroy
these components. Heat absorbing compounds or “wet rags” must be used when brazing the
refrigerant line connections. The suction line sensor should be removed before brazing.
Power Supply
The Beacon II board gets its 24 VAC power supply from a transformer mounted in the electrical end of each
evaporator. On 208-240 volt systems the multi-tap transformer is shipped from our factory wired for 240
volts. If your supply voltage is 208 volt you must change to the 208 volt tap on the transformer.
VERY IMPORTANT: If the supply voltage to the evaporator is 208 volts, the primary tap of the transformer
must be moved to the 208 volt tap.
This must be done for all the evaporators on that system.
If the 24 VAC power supply falls below 18 VAC the system may power down and shut off. When the power
supply is corrected to 24 VAC the system will restart after the four minute hold-off period and resume normal
operation.
On Beacon II systems the main power for the evaporator can be supplied separately from the power supply
of the condensing unit. All wiring, however, must comply with local electrical codes.
Wiring
Wiring between the condensing unit and the unit cooler(s) will be as follows (see attached wiring diagrams):
• High voltage – There may be high voltage on the defrost heater relay and the fan relay. The evaporator
may also be connected to a separate power supply from the condensing unit. See unit cooler spec. plate
for ampacity.
• Low voltage – 24V Class II control circuit. A total of five low voltage leads are required to connect the
condensing unit to the evaporator (see wiring diagram). Two of these leads are for connecting the outdoor
temperature sensor. The other three leads are for connecting the compressor relay, service relay and 24V
Common inputs.
All 24 volt wiring must be run separate from the line voltage wiring.
• Low voltage wiring must be 18 gauge minimum. For low voltage wiring, maximum distances are:
Condensing unit to MASTER evaporator 500 ft.
Smart Controller to MASTER evaporator 1,000 ft.
• Alarm circuit – The onboard alarm is a dry set of NC contacts which closes to indicate an alarm. The type
and wiring for the alarm is customer specified. Note that the alarm circuit does not distinguish or indicate
what has caused the alarm.
• All wiring must comply with all applicable codes and ordinances.
Box Temperature Control Settings
• There is an on board room thermostat on the Beacon II board which can be adjusted to the desired
room temperature. The temperature differential is 2°F.
Temperature Differential
When a system is in the cooling mode and the box setpoint is 35°F, the system will continue to cool until
the box temperature gets to 34°F. At this point the compressor will pumpdown and shut off. The system
will restart cooling when the box temperature has risen to 36°F.
It is important to note that Beacon II has a minimum 2-minute “ON” time and a minimum 4-minute “OFF”
time. This means that the system will run in the cooling mode a minimum of 2 minutes even if the
setpoint temperature is met. In applications where the system is grossly oversized, the box temperature
could go below the differential temperature before the system cycles off.
In the “OFF” cycle, the system will be off for a minimum of 4 minutes even if the box temperature goes
above the differential temperature before cooling will be restarted.
• The on board room thermostat is factory set at 35°F for air defrost systems and -10°F for electric
defrost systems.