Functional description
The hot gas bypass solenoid valve
will be controlled by a normally open
(NO) relay output. Energizing the
solenoid will open the valve.
Freeze avoidance or evaporator limit
will also operate while in the hot
gas-bypass mode. Shutdown of the
unit when in hot gas-bypass due to
evaporator limit will not result in any
diagnostics and the unit will restart
normally when there is a need to
run.
Total time spent in hot gas bypass
mode will be recorded and available
to the user.
Design details
The following rules will be applied to
hot gas bypass operation, if hot gas
bypass is installed and enabled.
1. Hot gas bypass will be opened
when the circuit is running with
compressors at the minimum
(first) capacity step and the control
algorithm requires a further
reduction in capacity.
2. Hot gas bypass will be closed at
circuit startup.
3. Hot gas bypass will be closed
when it is already open, but
additional capacity is required.
4. Hot gas bypass will be closed
and the circuit shut down if the
unit has been running with hot
gas-bypass for more than the hot
gas-bypass time limit.
5. Hot gas bypass will be closed and
the compressor shut down if the
saturated suction temperature
for Circuit 1 gets below the Low
Refrigerant Temperature Cutout
+ 0.5°C.
Capacity control modes
RAUL units support air temperature
control and external capacity control
(optional), which are described
below. At least one of these options
must be configured.
Air temperature control (standard)
Units with an evaporator leaving
air temperature sensor is capable
of air temperature control. Air
temperature control is used on RAUL
units if the external capacity control
feature is not selected.
Air temperature control will
require an active air temperature
setpoint, based on a front panel air
temperature setpoint, an external
air temperature setpoint, a BAS air
temperature setpoint, and a local
schedule air temperature setpoint.
These settings are displayed on
DynaView and TechView similarly
to the existing chilled water setpoint
values.
The capacity control method is
identical to that used for chilled
water control, with setting changes
being used to adjust the control
appropriately.
External capacity control (option)
Optional replace air temperature
control
External capacity control be a
configurable option for RAUL units.
The configuration options are as
follows:
• Not Installed
• 2 Low Voltage Binary Inputs
(2 capacity steps)
• 3 Low Voltage Binary Inputs
(3 capacity steps)
• 4 Low Voltage Binary Inputs
(4 capacity steps)
When in external capacity control
mode, the unit is in AUTO command
mode, and there is no need to run,
«waiting for need to run» submode
is displayed.
Communication failure with any
of the external capacity control
hardware inputs will cause a
shutdown of the unit if the external
capacity control feature is configured
and enabled.
External capacity control overrides
any other capacity control mode
except manual control mode if
enabled.
11
RAU-SVX01F-E4
Installation
Summary of Contents for Voyager YC 600
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