Safety Features - Geostar ASTON SERIES Installation Manual

The Aurora 'Base' Control System cont.

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.
Anti-Short Cycle Protection – 4 minute anti-short cycle protection
for the compressor.
Random Start – 5 to 80 second random start upon power up.
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.
ASTON INDOOR SPLIT SERIES INSTALLATION MANUAL
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 blower is started immediately and 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. The ECM blower
will shift to high speed.
Heating, 3rd Stage (Y1, Y2, W) - The hot water pump is de-
energized and 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 blower is started immediately and
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. The ECM blower
will shift to high speed.
Blower (G) - The blower will start immediately upon receiving a
thermostat G command. If there are no other commands from the
thermostat the ECM will run on "G" speed until the G command is
removed. Regardless of blower input (G) from the thermostat, the
blower will remain on for 30 seconds at the end of each heating,
cooling, and emergency heat cycle.
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