106 Print Reading for HVACR
Copyright Goodheart-Willcox Co., Inc.
5.4 Duct System Accessories
Other accessories can go into a duct system to help it function in an effec-
tive and effi cient manner. Some accessories help a service technician gain
access to unreachable components in the duct system, while others act to
ensure the safety and well-being of the occupants.
Registers, grilles, and louvers are the portions of an air distribution
system that are located in the conditioned space and are visible to the
occupants. These are the decorative framed panels that are the transi-
tion points between the occupied space and the duct system. Although
the terms for them are sometimes used interchangeably in the HVACR
industry, these accessories are not the same. In different industries and
applications, these terms take on different meanings.
5.4.1 Registers, Grilles, Louvers, and Diffusers
Typically, in the HVACR industry, the term louver is used to describe a
framed set of fi xed slats that cover an opening in a duct, doorway, or
other construction element. Air is able to pass through the louver and be
directed in a particular path, while somewhat limiting the ability to see
through the louver to the other side.
Grilles, like louvers, are a framed set of slats. However, some grilles
can have their slats adjusted, Figure 5-42. Both grilles and louvers are
unable to control the volume of air that passes through them, but grilles
can with the use of a register. A register is the combination of an adjust-
able grille and a damper. It can control the direction of airfl ow and the
volume of air passing through it.
Diffusers are designed to minimize the stratifi cation of air and effec-
tively mix the supply airstream with air already in the occupied space.
Diffusers help ensure uniform air conditioning by reducing hot or cold
spots due to ineffective or uneven airfl ow patterns. They can dispense air
in many directions, which makes them more effective than registers in
this regard. Be sure to refer to the notes that accompany duct drawings in
any project. They will clearly identify the specifi c devices to be used, thus
eliminating any confusion.
Goodheart-Willcox Publisher
Figure 5-41 (continued ).
Return-side tee fittings
10-B
10-A
10-C
Louver Grille
Goodheart-Willcox Publisher
Figure 5-42. A—Louvers have stationary vanes. B—Grilles have the ability to adjust
the pitch of the vanes.
Copyright Goodheart-Willcox Co., Inc.
5.4 Duct System Accessories
Other accessories can go into a duct system to help it function in an effec-
tive and effi cient manner. Some accessories help a service technician gain
access to unreachable components in the duct system, while others act to
ensure the safety and well-being of the occupants.
Registers, grilles, and louvers are the portions of an air distribution
system that are located in the conditioned space and are visible to the
occupants. These are the decorative framed panels that are the transi-
tion points between the occupied space and the duct system. Although
the terms for them are sometimes used interchangeably in the HVACR
industry, these accessories are not the same. In different industries and
applications, these terms take on different meanings.
5.4.1 Registers, Grilles, Louvers, and Diffusers
Typically, in the HVACR industry, the term louver is used to describe a
framed set of fi xed slats that cover an opening in a duct, doorway, or
other construction element. Air is able to pass through the louver and be
directed in a particular path, while somewhat limiting the ability to see
through the louver to the other side.
Grilles, like louvers, are a framed set of slats. However, some grilles
can have their slats adjusted, Figure 5-42. Both grilles and louvers are
unable to control the volume of air that passes through them, but grilles
can with the use of a register. A register is the combination of an adjust-
able grille and a damper. It can control the direction of airfl ow and the
volume of air passing through it.
Diffusers are designed to minimize the stratifi cation of air and effec-
tively mix the supply airstream with air already in the occupied space.
Diffusers help ensure uniform air conditioning by reducing hot or cold
spots due to ineffective or uneven airfl ow patterns. They can dispense air
in many directions, which makes them more effective than registers in
this regard. Be sure to refer to the notes that accompany duct drawings in
any project. They will clearly identify the specifi c devices to be used, thus
eliminating any confusion.
Goodheart-Willcox Publisher
Figure 5-41 (continued ).
Return-side tee fittings
10-B
10-A
10-C
Louver Grille
Goodheart-Willcox Publisher
Figure 5-42. A—Louvers have stationary vanes. B—Grilles have the ability to adjust
the pitch of the vanes.