Airedale SmartCool 11-233kW - Manual (Page 164)

SmartCool
TM
- D Precision Air Conditioning
164
Precision Air Conditioning
Installation, Maintenance and Commissioning Manual :6877419 02/2013
Commissioning Data
Electronic Expansion
Valves (EEV)
(Optional extra)
Electronic expansion valves differ to the normal thermostatic expansion valves in their
ability to maintain control of the suction superheat at reduced head pressures. This can
lead to significant energy savings particularly at reduced loading and low ambient
temperatures.
EEV step position, superheat setpoint, head pressure set point and other features can be
viewed and adjusted via the microprocessor display keypad.
Low Noise Feature for
Condenser Fan
(Optional Extra)
(X Models)
Specifically designed for night time operation as optimum low noise levels are achieved
with reduced ambient temperature and room loads, this feature is also ideal for residential
and other outdoor noise critical applications.
Initiated by setting the microprocessor programmable time clock (optional), the head
pressure set point changes from the standard 26 barg (377 psig) (TEV) or 22 barg (319
psig) (optional EEV) to 34 barg (493 psig), reducing the outdoor unit fan speed and
corresponding operating sound levels.
Head Pressure Control
Head Pressure Control -
Intelligent Modulation
(X Models) The system is fitted with a voltage regulating fan speed controller which allows set point
adjustment and system monitoring via the indoor unit
microprocessor controller.
A pressure transducer is fitted to the liquid line which in turn feeds back the head
pressure to the microprocessor. The condenser fan speed can then modulate via the
controller to provide optimum control under varying ambient conditions. The head
pressure can be monitored via the display keypad.
Head Pressure Control
(WX Models) The head pressure is controlled by a combination of 3 way regulating valve and dry
cooler fan speed over two varying stages of control.
The 3 way valve operates at the first stage of head pressure control; allowing water to
flow to the condenser, bypass or both, to maintain correct refrigerant head pressure.
As the pressure increases the 3 way valve opens further rejecting the heat from the
condenser to the dry cooler.
The valve reaches the maximum position for stage one of head pressure control at which
point the Dry cooler fan speeds up to assist in heat rejection by means of further free
cooling from the ambient temperature.
The 3 way valve then continues to open fully with the control based upon the dry cooler
fan speed.
The dry cooler fan controls the available cooling potential based upon head pressure
rather than the conventional method of water temperature. This makes the dry cooler
capable of varying heat rejection capacities.
A pressure transducer is fitted to the liquid line which enables the head pressure to be
monitored via the display keypad.
Dry coolers do not have any legionnaires risk as they are dry systems unlike cooling
towers.
Factory Setting Units fitted with thermostatic expansion valves (TEV) have the head pressure factory set
to 26 barg (377 psig).
Units fitted with optional electronic expansion valves (EEV) have the head pressure
factory set to 22 barg (319 psig).
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