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ASTON COMPACT INSTALLATION MANUAL
Lockout Mode
Lockout mode can be activated by any of the following fault
signals: refrigerant system high pressure, refrigerant system low
pressure, freeze detection, and condensate overflow. When any
valid fault signal remains continuously active for the length of its
recognition delay, the controller will go into fault retry mode, which
will turn off the compressor. After the Compressor short cycle
delay, the compressor will attempt to operate once again. If three
consecutive faults occur in 60 minutes during a single heating or
cooling demand, the unit will go into lockout mode, turning off the
compressor, enabling the alarm output, and setting the blower back
to low speed operation until the controller is reset. If the control
faults due to the low pressure input (BI-3) being open during the
pre-compressor startup check, the control will go into lockout mode
immediately, disabling the compressor from starting and enabling
the alarm output (BO-6). The lockout condition can be reset by
powering down the controller, by a command from the BAS, or by
the holding the ESC and Return keys on the MUI for 5 seconds.
Freeze Detection (AI-5)
The freeze detection sensor will monitor the liquid refrigerant
temperature entering the water coil in the heating mode. If the
temperature drops below the freeze detection trip point for the
recognition delay period, the condition will be recognized as a fault.
The freeze detection trip point will be factory set for 30°F (-1°C) and
will be field selectable for 15°F (-9°C) by removing a jumper wire on
BI-5. The freeze detection fault condition will be bypassed 2 minutes
at normal compressor startup, to allow the refrigeration circuit to
stabilize. If the freeze detection sensor becomes unreliable at any
time compressor operation will immediately be suspended until the
problem is corrected. This should be displayed as an alarm on the
BAS and the MUI. This alarm will be reported as a “Water Low Temp
Limit” fault.
High Pressure (BI-11)
The high-pressure switch shall be a normally closed (NC) switch
that monitors the systems refrigerant pressure. If the input senses
the high-pressure switch is open it must disable the compressor
output immediately and count the fault. The compressor minimum
on time does not apply if the high-pressure switch opens. The
compressor will not restart until the compressor short cycle time
delay has been satisfied.
Low Pressure (BI-3)
The low-pressure switch shall be a normally closed (NC) switch
that monitors the systems refrigerant pressure. The input shall be
checked 15 seconds before compressor start up to be sure the
pressure switch is closed and then ignored for the first 2 minutes
after the compressor output (BO-2) is enabled. If the switch is
open continuously for (30) seconds during compressor operation
the compressor output (BO-2) will be disabled. The compressor
will not restart until the compressor short cycle time delay has
been satisfied.
Condensate Overflow
The condensate overflow sensing circuit will monitor the
condensate level as a resistance input to AI-3. If the condensate
water level rises resulting in the input resistance rising above the
set point for the recognition delay period, the condition will be
recognized as a fault. The condensate will be subjected to a (30)
second lockout delay which requires that the fault be sensed for a
continuous (30) seconds before suspending unit operation.
Alarm Output (BO-6)
The alarm output will be enabled when the control is in the lockout
mode and will be disabled when the lockout is reset.
Test Mode
Raising the zone temperature input (AI-1) reading to 180–220°F or
by holding the ESC and down arrow keys on the MUI for 5 seconds
will put the control into test mode. In test mode the random start delay
and the compressor fixed on delay time will both be shortened to
5 seconds and the reversing valve will be allowed to cycle with out
shutting down the compressor. If an MUI is connected to the control
LED 8 will flash and the words “Test Mode Enabled” will be shown
on the LCD display when the control is in test mode. Test mode will
be disabled after a power cycle, 30 minute timeout, or by holding the
ESC and Up arrow keys on the MUI.
Sequence of Operation
Power Fail Restart
When the controller is first powered up, the outputs will be
disabled for a random start delay. The delay is provided to prevent
simultaneous starting of multiple heat pumps. Once the timer
expires, the controller will operate normally.
Random Start Delay
This delay will be used after every power failure, as well as
the first time the compressor is started after the control exits
the unoccupied mode or the emergency shutdown mode. The
delay should not be less than 1 second and not longer than 120
seconds. If the control is in test mode the random start delay will be
shortened to 5 seconds.
Controls - FX10 (optional) cont.
Summary of Contents for Aston Compact Series
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