Airedale Air Cooled Condensers R407C - Manual (Page 19)

CONDENSERS C11 - 45 / CS50 - 105
Condensers
19
Installation and Maintenance Manual: 6259642 V1.2.0 10/2013
Commissioning Data
OPERATING LIMITS
Standard On/Off Head Pressure Control
Minimum Ambient Air DB °C
-0°C
Maximum Ambient Air DB °C +48
Optional Variable Speed Head Pressure Control
Minimum Ambient Air DB °C
-20°C
Maximum Ambient Air DB °C +48
CONTROL DEVICES –
ADJUSTMENT
The condenser is fitted with a head pressure control device which can be either:
1 On/Off pressure switch (standard)
2 Variable speed control (option)
The control device is factory pre-set.
To check the setting connect a pressure gauge with scale reading up to at least 30bar to
the pressure tapping located in the inlet manifold of the condenser and watch the
operation of the fan as the pressure changes. If the settings require adjustment, follow the
instructions set out below and check new settings as explained above.
CAUTION Before carrying out any work, ensure that the isolator is switched off.
On-Off Pressure Switch The control device comprises a pressure switch with on/off contact which cycles
operation of the fan as a function of the pressure; the contact:

Closes and feeds the fan motor when the pressure rises and reaches the
set point (18 Barg).

Opens when the pressure falls to a level equal to the set point value, minus the
differential pressure pre-set (14 Barg).
This type of control system is suitable where ambient temperatures seldom fall
below
0˚C.
In cold climates it could cause excessive hunting of the system.
The values of Set and Differential are adjusted by means of the adjusting screws which
are accessed by removing the external casing of the pressure switch.
Factory setting: Set = 18 Barg
Differential = 4 Barg
Variable Speed Control The fan speed is controlled via alteration of the supply voltage which corresponds to a
particular condensing pressure. The output voltage from the controller varies between a
maximum of 95% and a minimum of 40% of the mains voltage (ie 220 Volts down to
approximately 90 Volts on a 230 Volt supply) as the condensing pressure varies within a
band of 5 Bar.
The control system is suitable for temperatures down to -20°C.
The pressure set point corresponding to the maximum output voltage can be adjusted by
means of a potentiometer internal to the case of the controller.
Factory setting: Set = 18 Barg