60
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S
HEET
M
ETAL
/HVAC
P
RO
C
ALC
Inline Duct, Single Offset (Computing Offset, Length, and Angle)
When working with the process of direct measure between two ducts
#1 and #2, as diagramed below, one leg of “The Measured Triangle”
“
I
” should
use the larger horizontal dimension
of the two ducts.
Therefore, in this scenario, the 42 Inches dimension of duct #2 is
used since it is the larger of the two ducts.
To calculate the angle A
0
in “The Measured Triangle” “
I
” and the
dimensions of θ1, X1, and Y1 in triangle “
II
,” follow the sequence of
input given below to solve for the dimensions in question.
Note: “x” or “y” can represent either Offset or Length, the order dictated by the initial
setup and perspective. In the setup, placement of the Right-Triangle should always
allow for the angle of “
θ
” in triangle “
II
” to be established by simple subtraction of
angle “
A
0
” from a known angle like 180°, as in the example below.
Find Theta θ, “x”, and “y” if the sides of the Measured Triangle “I”
are: 8 Feet 2-3/8 Inches, 42 Inches, and 6 Feet 10 Inches. See
diagram below.
(Cont’d)
