Airedale SmartCool 11-233kW - Manual (Page 34)

SmartCool
TM
- D Precision Air Conditioning
34
Precision Air Conditioning
Installation, Maintenance and Commissioning Manual :6877419 02/2013
Constant Pressure
Control Constant pressure control is a method of controlling air pressure within a space, such as
a floor void or a duct. The air pressure is controlled using a variable speed fan that is
modulated to maintain a given set point.
Constant pressure control monitors the air pressure differential between two points. In a
typical application (shown below) the pressure under the raised floor (red) is compared
to the room pressure (blue).
The two pressure points, positive and negative, are routed back to an air differential
pressure sensor inside the CRAC unit. The value from the air pressure sensor is
compared to the set point and a fan speed demand is generated, to maintain the
required pressure differential.
It is the responsibility of the installer to fit the air pressure sensor(s). The sensor shall be
located under the false floor with the 6mm flamtronix tubing routed back into the control
panel of the unit (the tubing must not be obstructed /damaged to ensure accurate
pressure control).
The constant pressure system shall be commissioned by Airedale following routing of
tubing from the pressure diffuser and the unit.
A maximum of 8m/s air velocity is allowed at the diffuser so consideration must be made
when locating the diffuser.
Constant Air Volume Constant air volume is a method of automatically adjusting the unit fan speed to deliver a
specific air volume.
When faced with a change in system resistance, the fan speed modulates to obtain the
air volume set point.
Constant air volume monitors the air pressure differential between two points. These two
pressure points, positive and negative, are routed back to an air differential pressure
sensor inside the unit
In
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Underfloor
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Room
Pressure