Installation manual

19
5 SERIES 500RO11 INSTALLATION MANUAL
Safety Features
The following safety features are provided to protect the
compressor, heat exchangers, wiring and other components
from damage caused by operation outside of design conditions.
Fuse – a 3 amp automotive type plug-in fuse provides
protection against short circuit or overload conditions.
A
nti-Short Cycle Protection – 4 minute anti-short cycle
protection for the compressor.
Random Start – 5 to 80 second random start upon power up.
Low Loop Temperature (Outdoor Split Units Only) – The
unit also contains a secondary freeze detection sensor
located on the entering water line of the unit. If the loop
reaches a temperature of 20°F the secondary freeze
detection sensor will cycle the loop pumps "on" until the
loop temperature rises to or above 25°F.
Fault Retry – in the fault condition, the control will stage off
the outputs and then “try again” to satisfy the thermostat
Y input call. Once the thermostat input calls are satisfied,
the control will continue on as if no fault occurred. If 3
consecutive faults occur without satisfying the thermostat
Y input call, then the control will go to Lockout mode.
Lockout – when locked out, the blower will operate
continuously, and PSC blower motor output will remain on.
The Alarm output (ALM) and Lockout output (L) will be
turned on. The fault type identification display LED1 (Red)
shall flash the fault code. To reset lockout conditions with
SW2-8 On, thermostat inputs “Y1”, “Y2”, and “W” must be
removed for at least 3 seconds. To reset lockout conditions
with SW2-8 Off, thermostat inputs “Y1”, “Y2”, “W”, and “DH”
must be removed for at least 3 seconds. Lockout may also
be reset by turning power off for at least 30 seconds or by
enabling the emergency shutdown input for at least 3 seconds.
High Pressure – fault is recognized when the Normally
Closed High Pressure Switch, P4-9/10 opens, no matter
how momentarily. The High Pressure Switch is electrically in
series with the Compressor Contactor and serves as a hard-
wired limit switch if an overpressure condition should occur.
Low Pressure - fault is recognized when the Normally
Closed Low Pressure Switch, P4-7/8 is continuously open
for 30 seconds. Closure of the LPS any time during the 30
second recognition time restarts the 30 second continuous
open requirement. A continuously open LPS shall not be
recognized during the 2 minute startup bypass time.
Loss of Charge – fault is recognized when the Normally
Closed Low Pressure Switch, P4-7/8 is open prior to the
compressor starting.
Freeze Detection (Coax) - set points shall be either 30°F
or 15°F. When the thermistor temperature drops below
the selected set point, the control shall begin counting
down the 30 seconds delay. If the thermistor value rises
above the selected set point, then the count should reset.
The resistance value must remain below the selected set
point for the entire length of the appropriate delay to be
recognized as a fault. This fault will be ignored for the initial
2 minutes of the compressor run time.
Over/Under Voltage Shutdown - An over/under voltage
condition exists when the control voltage is outside the
range of 18 VAC to 30 VAC. If the over/under voltage
shutdown lasts for 15 minutes, the lockout and alarm relay
will be energized. Over/under voltage shutdown is self-
resetting in that if the voltage comes back within range
of 18 VAC to 30 VAC for at least 0.5 seconds, then normal
operation is restored.
Operation Description
Power Up - The unit will not operate until all the inputs and
safety controls are checked for normal conditions. The unit
has a 5 to 80 second random start delay at power up. Then
the compressor has a 4 minute anti-short cycle delay after
the random start delay.
Standby In standby mode, Y1, Y2, W, DH, and G are not
active. Input O may be active. The blower and compressor
will be off.
Heating Operation
Heating, 1st Stage (Y1) - The compressor is energized 10
seconds after the Y1 input is received.
Heating, 2nd Stage (Y1, Y2) - The compressor will be
staged to full capacity 20 seconds after Y2 input is received .
Heating, 3rd Stage (Y1, Y2, W) - The first stage of electric
heat is energized 10 seconds after the W command is
received. If the demand continues the second stage of
electric heat will be energized after 5 minutes.
Emergency Heat (W Only) - When the unit is matched with
an air handler listed in the Air Handler Compatibility table,
the thermostat will send the "W" input to the air handler's
control board. The blower is started on high speed, and the
first stage of resistance heat is energized 10 seconds after
the "W" input. Continuing demand will engage the additional
stages of resistance heat 90 seconds after the first stage.
Cooling Operation
In all cooling operations, the reversing valve directly tracks
the O input. Thus, anytime the O input is present, the
reversing valve will be energized.
Cooling, 1st Stage (Y1, O) - The compressor is energized 10
seconds after the Y1 input is received.
Cooling, 2nd Stage (Y1, Y2, O) - The compressor will be
staged to full capacity 20 seconds after Y2 input is received.
Blower (G) - The blower will start immediately upon
receiving a thermostat G command. If there are no other
commands from the thermostat the blower will run on “G”
speed until the G command is removed.
The Aurora ‘Base’ Control System cont.