102 Print Reading for HVACR
Copyright Goodheart-Willcox Co., Inc.
To provide more details, the drawing of the offset fi tting often includes the
direction of airfl ow, if the fi tting rises or drops in the direction of the air-
fl ow, and how much the fi tting rises or drops. This is shown in Figure 5-31.
Another way to indicate whether the fi tting is rising or dropping is
to identify the distance of each side of the transition from either the fl oor
or ceiling. The following abbreviations are often used in duct drawings:
■ TU (Top Up). How far the top of the duct section is from the fl oor.
■ TD (Top Down). How far the top of the duct section is from the
ceiling.
■ BU (Bottom Up). How far the bottom of the duct section is from
the fl oor.
■ BD (Bottom Down). How far the bottom of the duct section is from
the ceiling.
Figure 5-32 shows the plan view of a portion of a duct run that has a
transition fi tting. The left side of the transition fi tting is labeled TU 8′1″,
which indicates the top of the duct is 8′1″ up from the fl oor. The right
side of the transition fi tting is labeled TU 8′7″, which indicates that the
top of the duct is 8′7″ up from the fl oor. From this information, it can be
determined that the fi tting is rising from left to right and that the amount
of rise is 6″.
Horizontal Offset Fittings
A horizontal offset fi tting, Figure 5-33, is used to move a duct run to
avoid vertical barriers. Most of the time, horizontal offset fi ttings are not
included as part of the original ductwork plan for the project. However,
this type of fi tting, along with the vertical offset, are often added during
the installation process when unforeseen obstacles present themselves.
Rise 6″
Drop 6″
A
B
Goodheart-Willcox Publisher
Figure 5-31. Vertical offsets. A—Fitting is rising 6″ from left to right. B—Fitting is
dropping 6″ from left to right.
TU 8’ 1” TU 8’ 7”
Goodheart-Willcox Publisher
Figure 5-32. A plan view of a portion of a duct run with a transition fi tting.
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Copyright Goodheart-Willcox Co., Inc.
To provide more details, the drawing of the offset fi tting often includes the
direction of airfl ow, if the fi tting rises or drops in the direction of the air-
fl ow, and how much the fi tting rises or drops. This is shown in Figure 5-31.
Another way to indicate whether the fi tting is rising or dropping is
to identify the distance of each side of the transition from either the fl oor
or ceiling. The following abbreviations are often used in duct drawings:
■ TU (Top Up). How far the top of the duct section is from the fl oor.
■ TD (Top Down). How far the top of the duct section is from the
ceiling.
■ BU (Bottom Up). How far the bottom of the duct section is from
the fl oor.
■ BD (Bottom Down). How far the bottom of the duct section is from
the ceiling.
Figure 5-32 shows the plan view of a portion of a duct run that has a
transition fi tting. The left side of the transition fi tting is labeled TU 8′1″,
which indicates the top of the duct is 8′1″ up from the fl oor. The right
side of the transition fi tting is labeled TU 8′7″, which indicates that the
top of the duct is 8′7″ up from the fl oor. From this information, it can be
determined that the fi tting is rising from left to right and that the amount
of rise is 6″.
Horizontal Offset Fittings
A horizontal offset fi tting, Figure 5-33, is used to move a duct run to
avoid vertical barriers. Most of the time, horizontal offset fi ttings are not
included as part of the original ductwork plan for the project. However,
this type of fi tting, along with the vertical offset, are often added during
the installation process when unforeseen obstacles present themselves.
Rise 6″
Drop 6″
A
B
Goodheart-Willcox Publisher
Figure 5-31. Vertical offsets. A—Fitting is rising 6″ from left to right. B—Fitting is
dropping 6″ from left to right.
TU 8’ 1” TU 8’ 7”
Goodheart-Willcox Publisher
Figure 5-32. A plan view of a portion of a duct run with a transition fi tting.
24
x
20
24
x
20
24
x
20
24
x
20
24
x
20
24
x
20