RECORDING TOTAL SYSTEM CHARGE
The factory charge in the outdoor unit is listed in Table 5 and
includes enough charge for the unit, matched evaporator and
15 feet of lines. Installations over 15 feet long and some indoor
coil matches may require some additional charge. Table 6 lists
the refrigerant line charges.
The “TOTAL SYSTEM CHARGE” must be permanently
stamped on the unit data plate.
Total system charge is determined as follows:
1. Determine the condensing unit charge from Table 5.
2. Determine indoor coil adjustment charge from Table 5.
3. Calculate the additional charge for line lengths greater than
15 feet using Table 6 factors.
4. Total system charge = Item 1 + Item 2 + Item 3.
5. Permanently stamp the unit data plate with the total amount
of refrigerant in the system.
SYSTEMS FUNCTIONS
The dual compressor Stellar ULTRA air conditioner has unique
system functions as described below.
COOLING OPERATION
The condensing unit utilizes a two stage cooling indoor thermo-
stat. Depending on the cooling load requirements, the com-
pressors are energized in sequence by means of the two stage
thermostat.
With a call for first stage cooling (Y1), the outdoor fan and the
lead compressor are energized. Simultaneously, the variable
speed indoor blower motor is also energized and the blower
delivers the corresponding airflow adequate for the first stage
cooling load.
With a call for second stage cooling (Y2), the follower compres-
sor is also energized. Simultaneously, the variable speed
blower now delivers the rated CFM in order to satisfy the
cooling demand. The follower compressor is energized only
when cooling demand is not met by the lead compressor
running alone. Once the second stage building load is satisfied,
the unit will operate with only the lead compressor, until first
stage indoor cooling thermostat is satisfied, or if there is a call
for second stage cooling operation.
SYSTEM CONTROL BOARD OPERATIONS
The Stellar ULTRA air conditioner utilizes a control board to
control as well as monitor the operation of the two stage cooling
system. The following is an overview of the functions of the
control board.
Control Board LED Functions
The control board used to control and monitor the operation of
the two stage cooling system has a LED mounted on the board,
which provides signals (Fault Codes) for several system op-
erations. See Table 7, which provides a list of LED functions
and definitions.
Power Supply
The five minute control board time delay is energized by means
of 24V power supply from the transformer installed in the indoor
variable speed air handler. As soon as the control board
receives power, it warms up for five minutes before it starts
operating. The control board also has a 3A fuse which protects
the control board from short circuiting.
Five Minute Time Delay (Control Board)
Every time the control board is powered after a power interrup-
tion, it will delay the operation for five minutes . The LED light
on the control board will blink "ON" for 1 second and "OFF" for
4 seconds, indicating a warm up period for the control board.
This will prevent the unit from short cycling.
Five Second Time Delay
A five second time delay is energized every time the board
receives a control signal Y1 or Y2 from the thermostat. This
prevents cycling of the unit and unnecessary operation of the
unit as a result of thermostat jiggling.
One Minute Inter Stage Time Delay
Anytime the unit receives a call for second stage cooling
operation (Y2) from the thermostat, when the lead compressor
is operating, there is a one minute time delay before the
follower compressor will start. The outdoor fan motor and the
lead compressor continue to run during this inter-stage time
delay.
Five Minute Time Delay (Compressor 1 and 2)
A five minute time delay prevents the system from short cycling
after a thermostat off cycle or power interruption.
There is a five minute time delay for both, the lead and the
follower compressor after a thermostat off cycle. These delays
are incorporated to prevent the short cycling of the unit. How-
ever, during the five minute delay on the follower compressor,
the lead compressor and the outdoor fan will continue to run,
together with the indoor variable speed air handler, if the call
for cooling still exists.
For servicing or during installation of the condensing unit, the time
delay may be overridden by momentarily jumpering the test
terminal and "R" terminal on the board if necessary. However,
the jumper must be removed during normal operation.
Pressure Switches
High and low pressure switches are installed and wired in
series. They provide addtional protection for the system if any
abnormal operating conditions occur. If the control board
senses a tripping of the high or low pressure switch, the control
will provide a five minute delay before the system starts oper-
ating again. The LED will blink rapidly indicating that there is a
550.37-N1Y
Central Environmental Systems
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