In a ducted air conditioning, the air is delivered to each area through a diffuser. The diffuser spreads the air across the area.

The air diffuser sizing is determined by:

  • The area to be cooled/heated
  • The dimensions of the area length and width
  • The aesthetics of the space
  • The height of the ceiling
  • Larger diffusers/ducts move more air with less static. Static is resistance to the airflow.
    Undersized diffusers will restrict airflow and create noise. Oversized diffusers can look out of place.
  • Correct sizing is important.

 

Area                       Ceiling Height         Diffuser size(dia.)
Up to 12 sqm          2.4 – 2.7m                200mm
Up to 12 sqm          3m                            250mm
Up to 20 sqm          2.4m – 2.7m             250mm
Up to 20 sqm          3m                            300mm
Over 20 sqm                                           multiple diffusers

Note that the size of the diffuser is the diameter of the neck to which the duct is connected.

Supply Air Diffuser Sizing and Location - Crown Power At Work

The size of the diffuser is the diameter of the neck to which the flexible duct is connected.

E.g. an average size bedroom is approximately 3m x 3m. This room requires 1 x 200mm round diffuser.

Diffuser layout

Small Rooms

Bedroom: Locate the diffuser at the end of the bed
Study: Locate the diffuser in the centre
Ensuite: Locate the diffuser in the centre but away a source of steam e.g. shower

Large Rooms/Areas

The round diffuser will spread the air approx. 3m. If the room is longer than 5m then use multiple diffusers spaced at up to 6m apart and up to 3m from the wall. Ducted air conditioning will be softer when the air is coming from many directions. Therefore 2 smaller diffusers will provide softer air conditioning than 1 large diffuser.

E.g. A living room 6m long x 4m wide 2.7m ceiling.

Locate one 200mm diffuser 2m from the longer wall and 2m from the shorter wall. Locate a second 200mm diffuser 2m from the wall at the other end of the room.
Practical considerations limiting the ideal location of diffusers:

1 Lights, ceiling roses, skylights, ceiling fans etc.

2 Beams and ceiling joists

3 Insufficient roof space

Supply Air Diffuser Sizing and Location

Working - Crown Power )Supply Air Diffuser Sizing and Location)

Supply Air Diffuser Sizing and Location - Crown Power at work

The raked ceiling does not allow space for a ceiling diffuser. A side wall diffuser is used(grill not installed in this pic.

 

The final layout will be determined by the installer and the client. Get in touch with Crown Power to know more about supply air diffuser sizing and any other air conditioning related queries you might have.