Constant Air Ceiling Diffusers (CACD, CASD, CARD) | rickardair

Constant Air Ceiling Diffusers (CACD, CASD, CARD)

The RICKARD Constant Air Ceiling Diffusers (CACD/CASD/CARD) have been designed to offer greater savings by removing the manually adjustable damper. This diffuser suits applications where the diffusers volume will not need to be reduced. The aesthetic, airflow pattern, and quality matches the rest of the Rickard product range.

Good Coanda, Velocity and Throw at catalogue pressures i.e. 10-60Pa total pressure.
Good Air Change Effectiveness.
Good ADPI values.
Aerodynamically shaped diffuser components for reduced noise and improved air flow characteristics.

Easy installation, as there are no moving parts.

Included plastic packaging  can be used to protect the tile once installed.
Low diffuser height (100mm) can reduce a buildings overall cost by reducing the height of the ceiling void.

Face Plate Mounting structure not visible from within the air-conditioned space.

Indented diffuser edge detail ensures the face of the diffuser is flush with the underside of the ceiling tee frame.
High Quality Epoxy Powder Coated Finish available in a wide range of colours. Matt White comes as standard.

Zero maintenance.

Stainless steel safety cable ensures that internal components remain attached in the event of building fire.


RICKARD Constant Air Ceiling Diffusers are intended for use in internal zones of a building where uniform radial discharge is the most suitable supply air pattern.  Normally these zones are less complex to air-condition as load fluctuations are not as severe as those on the perimeter. The Constant Volume Ceiling Diffuser, as its name implies, does not automatically regulate the air volume entering the conditioned space - they are constant volume devices.  Consequently, room temperatures will vary with room loads (assuming the duct air temperature and pressure remain constant).
This diffuser suites applications where the diffusers volume will not need to be reduced. 

Should this method be decided upon, care should be taken in selection of the CACD/CASD/CARD diffusers to ensure dumping does not take place.

The Rickard CACD/CASD/CARD diffusers can be used to supply spaces that require heating or cooling. To ensure that dumping does not occur in cooling and stratification in heating care must be taken to supply the diffusers with adequate pressure.

The most important practical factors to consider in internal zones are noise levels and uniform air distribution without "dumping" or "coning" effects.  "Dumping" is the tendency for cold, dense air to leave the diffusers as a vertical column similar to a waterfall.  The effect of dumping is to overcool the person immediately below the diffuser while the person further away will not be cooled enough.  Dumping is eliminated by ensuring that the discharge air energy from the diffuser is adequate to distribute conditioned air evenly throughout the conditioned area and at the same time provide good secondary room air induction rates.  Providing the total pressure in the neck of the RICKARD CACD diffuser selected is not too low, dumping of conditioned cold air will not take place.

In the context of radial discharge ceiling diffusers, 'coning' occurs when two air streams travelling in opposite directions meet.  As a result a downward moving cone of air is produced which will have a similar effect to dumping.  Coning is avoided by ensuring that diffusers are placed far enough apart to eliminate drafts in the conditioned space.

The table CAV Ceiling Diffuser Performance Data shows the distance from the various diffusers at which air velocity has reduced to 0.25 m/s (50 ft/min) (the 'throw' of the diffuser).  Using this information, diffusers  should be situated in the ceiling such that two adjacent diffusers are separated by slightly less than the sum of their throws.  Exactly how much less depends largely on the ceiling height and the amount of air movement desired in the conditioned spaced.  If the CACD is used in conjunction with Variable Linear Diffusers or Side Wall VAV Units, their throws should also be considered.

The drawing below describes how to determine the maximum ceiling height that can be achieved from a diffuser. Please see the diffuser performance data page for airflow, throw, noise and pressure information. 
  • Various Ceiling Styles available. Please see Ceiling Diffuser mounting methods.
  • Blanking Plates.

Please see relevant Sections for more information.
JUBILEE CLAMP: Saves time and material when attaching the flex.
VARIOUS CEILING DIFFUSER MOUNTING STYLES AVAILABLE: See Ceiling Diffuser Mounting Methods in this Catalogue Section.
BLANKING PLATES: 90, 180 or 270 degree Blanking Plates.