Copyright Goodheart-Willcox Co., Inc. 88
Introduction
An air distribution, or duct, system is one of the most common items
found on an air-conditioning print. A properly designed and installed
duct system helps ensure the continued satisfactory operation of the air-
conditioning system for years to come.
It is the responsibility of the print reader to perform proper
installation using duct drawings as a guide. Duct drawings vary based
on the methods and symbols used by the individual creating them. For
instance, elevation and plan views have the same concept but the notes
and symbols used on them likely differ. This chapter introduces you to a
variety of duct symbols and skills that allow you to extract information
from duct drawings and use them for installation. These skills are used
to estimate, fabricate, and install air distribution systems.
5.1 Duct Systems
All HVACR systems should provide thermal comfort to occupants of the
space. Thermal comfort includes temperature control, air cleanliness, humid-
ity, and air movement. When an air-conditioning system does its job properly,
the occupants should barely be aware the air-conditioning system is running.
An air distribution system is responsible for helping meet this goal. The air dis-
tribution system pulls air from the conditioned space, treats the airstream, and
then returns the treated air back to the conditioned space. A properly designed
and installed air distribution system helps ensure there is no excessive noise
and that adequate quantities of air are delivered to areas within the structure.
The air distribution system is made up of a series of ducts connected
to the air handler. A duct is a round or rectangular pipe used to carry con-
ditioned air. Poorly designed or installed ductwork will almost guarantee
that the occupants of the structure will not be comfortable.
Duct systems are designed, fabricated, and installed in strict compli-
ance with industry guidelines set forth by several organizations:
■ Air Conditioning Contractors of America (ACCA). ACCA is an
industry association mainly comprised of contractors that provide
indoor environment and energy services. ACCA writes standards for
the design, maintenance, installation, testing, and performance of
indoor environmental systems.
■ American Society of Heating, Refrigerating and Air Conditioning
Engineers (ASHRAE). ASHRAE is a global society that focuses on
building systems, energy effi ciency, indoor air quality, refrigeration,
and sustainability within the industry. ASHRAE concentrates
on research, standards writing, and publishing and providing
continuing education materials for the industry.
■ National Fire Protection Agency (NFPA). The NFPA is a US trade
association that creates and maintains standards and codes for use
and adoption by local governments.
■ Sheet Metal and Air Conditioning Contractors’ National Association
(SMACNA). SMACNA is an accredited, international trade association
that develops technical standards widely accepted by the HVACR and
construction community.
Technical Terms
branch runout
construction number
converging transition
damper
diffuser
diverging transition
duct
elbow
fi tting
grille
louver
offset
plenum
primary return trunk
primary supply trunk
register
return air duct
secondary supply trunk
supply air duct
takeoff fi tting
tee fi tting
transfer grille
transition
turning vane
Introduction
An air distribution, or duct, system is one of the most common items
found on an air-conditioning print. A properly designed and installed
duct system helps ensure the continued satisfactory operation of the air-
conditioning system for years to come.
It is the responsibility of the print reader to perform proper
installation using duct drawings as a guide. Duct drawings vary based
on the methods and symbols used by the individual creating them. For
instance, elevation and plan views have the same concept but the notes
and symbols used on them likely differ. This chapter introduces you to a
variety of duct symbols and skills that allow you to extract information
from duct drawings and use them for installation. These skills are used
to estimate, fabricate, and install air distribution systems.
5.1 Duct Systems
All HVACR systems should provide thermal comfort to occupants of the
space. Thermal comfort includes temperature control, air cleanliness, humid-
ity, and air movement. When an air-conditioning system does its job properly,
the occupants should barely be aware the air-conditioning system is running.
An air distribution system is responsible for helping meet this goal. The air dis-
tribution system pulls air from the conditioned space, treats the airstream, and
then returns the treated air back to the conditioned space. A properly designed
and installed air distribution system helps ensure there is no excessive noise
and that adequate quantities of air are delivered to areas within the structure.
The air distribution system is made up of a series of ducts connected
to the air handler. A duct is a round or rectangular pipe used to carry con-
ditioned air. Poorly designed or installed ductwork will almost guarantee
that the occupants of the structure will not be comfortable.
Duct systems are designed, fabricated, and installed in strict compli-
ance with industry guidelines set forth by several organizations:
■ Air Conditioning Contractors of America (ACCA). ACCA is an
industry association mainly comprised of contractors that provide
indoor environment and energy services. ACCA writes standards for
the design, maintenance, installation, testing, and performance of
indoor environmental systems.
■ American Society of Heating, Refrigerating and Air Conditioning
Engineers (ASHRAE). ASHRAE is a global society that focuses on
building systems, energy effi ciency, indoor air quality, refrigeration,
and sustainability within the industry. ASHRAE concentrates
on research, standards writing, and publishing and providing
continuing education materials for the industry.
■ National Fire Protection Agency (NFPA). The NFPA is a US trade
association that creates and maintains standards and codes for use
and adoption by local governments.
■ Sheet Metal and Air Conditioning Contractors’ National Association
(SMACNA). SMACNA is an accredited, international trade association
that develops technical standards widely accepted by the HVACR and
construction community.
Technical Terms
branch runout
construction number
converging transition
damper
diffuser
diverging transition
duct
elbow
fi tting
grille
louver
offset
plenum
primary return trunk
primary supply trunk
register
return air duct
secondary supply trunk
supply air duct
takeoff fi tting
tee fi tting
transfer grille
transition
turning vane