Chapter 5 Basic Duct Symbols and Drawings 97
Copyright Goodheart-Willcox Co., Inc.
■ 5-J radius elbow fi tting. Helps reduce air turbulence much better
than a 5-H and 5-I fi tting.
■ 5-K fi tting. Created by adding turning vanes to the 5-H square
elbow fi tting. This fi tting, even though it is a square elbow fi tting,
performs better than the 5-I and 5-J rounded fi ttings, due to the
addition of turning vanes.
Bullhead Fittings
Another commonly used return air fi tting is the bullhead, Figure 5-19.
This fi tting, just as with its supply-side equivalent, is popular because it is
made up of two separate, straight sections of ductwork. This allows for
adjustments and last-minute alterations to be made on the job. The bull-
head return air fi tting, with the tapered head, reduces turbulence. In some
cases, the return air is returning to the air handler from two different
directions. When this is the case, tee fi ttings are often used, Figure 5-20.
The most common tee is the 5-L bullhead tee, which has no turning vanes.
A 5-M vaned tee is more desirable in most applications.
Takeoff Fittings
On primary or secondary supply trunks, branch runouts bring air closer
to the point where it will enter the occupied space. The fi tting that con-
nects the branch runout to the main supply duct is called a takeoff fi tting.
There are many different types of takeoff fi ttings.
Air handler
5-L
Air handler
5-M
Return tees
Bullhead tee without turning vanes Bullhead tee with turning vanes
Return
air
Return
air
Goodheart-Willcox Publisher
Figure 5-20. Return bullhead tees with and without turning vanes at the air handler.
Goodheart-Willcox Publisher
Figure 5-19. Bullhead and bullhead with tapered head return air fi ttings at the air handler.
5-N
Air handler Air handler
Return
air
Bullhead return fitting
Return air fittings
Bullhead return fitting
with tapered head
5-O
Return
air
Copyright Goodheart-Willcox Co., Inc.
■ 5-J radius elbow fi tting. Helps reduce air turbulence much better
than a 5-H and 5-I fi tting.
■ 5-K fi tting. Created by adding turning vanes to the 5-H square
elbow fi tting. This fi tting, even though it is a square elbow fi tting,
performs better than the 5-I and 5-J rounded fi ttings, due to the
addition of turning vanes.
Bullhead Fittings
Another commonly used return air fi tting is the bullhead, Figure 5-19.
This fi tting, just as with its supply-side equivalent, is popular because it is
made up of two separate, straight sections of ductwork. This allows for
adjustments and last-minute alterations to be made on the job. The bull-
head return air fi tting, with the tapered head, reduces turbulence. In some
cases, the return air is returning to the air handler from two different
directions. When this is the case, tee fi ttings are often used, Figure 5-20.
The most common tee is the 5-L bullhead tee, which has no turning vanes.
A 5-M vaned tee is more desirable in most applications.
Takeoff Fittings
On primary or secondary supply trunks, branch runouts bring air closer
to the point where it will enter the occupied space. The fi tting that con-
nects the branch runout to the main supply duct is called a takeoff fi tting.
There are many different types of takeoff fi ttings.
Air handler
5-L
Air handler
5-M
Return tees
Bullhead tee without turning vanes Bullhead tee with turning vanes
Return
air
Return
air
Goodheart-Willcox Publisher
Figure 5-20. Return bullhead tees with and without turning vanes at the air handler.
Goodheart-Willcox Publisher
Figure 5-19. Bullhead and bullhead with tapered head return air fi ttings at the air handler.
5-N
Air handler Air handler
Return
air
Bullhead return fitting
Return air fittings
Bullhead return fitting
with tapered head
5-O
Return
air