Airedale SmartCool 11-233kW - Manual (Page 32)

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 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 contant 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 to its location.
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.
SmartCool™ 6 - 200kW Precision Air Conditioning
32
Introduction
SmartCool 6 - 200kW Chilled Water Technical Manual 7674716 V1.1.0_04_2014