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RC SERIES INSTALLATION MANUAL
Control and Safety Feature Details
Emergency Shutdown
The emergency shutdown mode can be activated by a command
from a facility management system or a closed contact on BI-2.
The default state for the emergency shutdown data point is off.
When the emergency shutdown mode is activated, all outputs will
be turned off immediately and will remain off until the emergency
shutdown mode is de-activated. The first time the compressor
starts after the emergency shutdown mode has been de-activated,
there will be a random start delay present.
Lockout Mode
Lockout mode can be activated by any of the following fault signals:
refrigerant system high pressure, refrigerant system low pressure,
water coil low temperature (freeze sensing), 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 fan 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.
Water Coil Low Temp (Freeze Sensing) Limit (AI-5)
The water coil low temperature (freeze sensing) limit sensor will
monitor the liquid refrigerant temperature entering the water coil
in the heating mode. If the temperature drops below the water coil
low temperature (freeze sensing) limit trip point for the recognition
delay period, the condition will be recognized as a fault. The
water coil low temperature (freeze sensing) limit trip point will
be factory set for 30°F and will be field selectable for 15°F by
removing a jumper wire on BI-5. The water coil low temperature
(freeze sensing) limit fault condition will be bypassed 2 minutes
at normal compressor startup, to allow the refrigeration circuit to
stabilize. If the water coil low temperature (freeze sensing) limit
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 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 cont.
