12
PXVC
AUGUST 2018
PXVC-DX
The PXVC –DX controller is a precision controller for
applications where superheat control is critical; offering
single point temperature and pressure sensing (sensor
sold separately), or customer supplied superheat values
via analog (4-20mA) input (Range 30°F subcooled liquid
to 30°F superheated vapor). Refer to the bulletin PT100c
for compatible superheat sensors (not included).
SYSTEM STARTUP:
1. During operation the power button is not available
to be used to stop the system, so before starting the
controller connect a remote interlock and close the
circuit to disable the controller.
2. Power on the controller and verify the screen is
flashing “OFF” to indicate the controller is not active.
If the interlock is not active, try operating the switch,
if this does not work power down the system and
check the controller jumpers, switch and wiring,
contact Hansen for further support.
3. Once interlock is disabled, verify the screen indicator
displays an underscore under the number “1,” as
shown in the user menus section. Screen #1, the
default screen, displays the measured value and the
set point. Screen two is only utilized on the PXVC-PT
which provides additional information in the form of
temperature and pressure readings.
4. Pressing the up or down arrows will increase or
decrease the set point
5. Pressing the left arrow will show the second screen
on applicable models.
6. Review the specifications for the evaporator or heat
exchanger and determine the necessary refrigerant
temperature for the equipment to function properly,
set suction pressure to appropriate value, observe
that the superheat set-point must be less than the
temperature differential between the media and the
refrigerant to attain stability.
7. Set the controller to the desired set point, and wait
for the controller to approach the desired set point
(%, degrees, PSI).
8. Replace interlock with temperature control interlock
(thermostat (dry contact) or system closed contact
control) to pins 13 and 14. Failure to do so will result
in inability to precisely control temperature and
undesirable operation. A manual interlock may be
used to override the system when wired in parallel
with the media temperature control interlock as
shown in Figure 6.
9. While controller is in operation and valve partially
open adjust the suction line pressure to attain the
desired refrigerant temperature, NOTE this will not
directly control media temperature, see step 8 for
media temperature control
10. Operating conditions should be monitored closely
during startup
System design considerations:
Where liquid may be
present, to precisely measure temperature, a trap is
required to be installed in the piping directly after the
sensing unit. This allows the saturated gas/liquid mixture
level to stabilize in the trap and the sensor to read the
temperature of the liquid which conducts heat much more
readily than gas, as shown in drawing Figure 8.
PXVC-DX
