Airedale Condensing Units (CU) 3kW - 80kW - Manual (Page 21)

Condensing Units
CUS 15 - 60 / HCU 20 – 30D
Chillers & Condensing Units
Installation & Maintenance:Part No: 6259592 IM 07/14
21
Commissioning Procedure
HEAD PRESSURE
CONTROLLER
ADJUSTMENT
CUS 15 - 30D AND HCU 20 - 30D
Cut Off Mode The voltage output to the fan is varied between 0-100% allowing head pressure
control in ambients down to -20
° C. This is selected by turning the knob on the fan
speed controller fully anti-clockwise. Cut off mode is standard operation for Airedale
condensing units and factory set.
Minimum Speed Mode The minimum voltage output to the fan can be varied between 45-95% of supply
voltage by adjusting the knob within the minimum speed mode on the fan speed
controller.
Head pressure setting adjustment is achieved by altering the slotted dead screw on
the pressure transducer.
CUS 40 - 60D
The head pressure can be controlled by the fan speed operation in one of two
possible modes:
The head pressure is controlled by a separate head pressure controller for each
refrigeration circuit. The head pressure controllers are enclosed in a plastic box which
contains all the necessary components including the pressure transducer. Connection
to the respective refrigeration circuit is via a capillary of suitable length.
There are Two control knobs in the controller.
The upper knob is used to set the minimum speed for the fans. This can be adjusted
to be between 50% and 90% of full speed. If the control is set to 0% then the minimum
speed function is disabled and the fan will operate over the whole range of 0% to
100% dependent upon the head pressure. 0% is the standard setting for these
controllers on Airedale condensing units.
The lower knob is used to adjust the proportional band of the controller. This should
be left at the factory setting.
Adjustment of head pressure setpoint is by means of the slotted head adjuster on the
pressure transducer head on the right-hand side of the controller.