9.
DUCTS AND DAMPERS DIMENSIONS (EXAM
P
LES OF CALCULATI
ON)
SIMPLIFIED METHOD
DISTRIBUTION SYSTEM
Du
ct
s si
ze
(h
eat
)
4 inch o
utlet
redu
ce by 1
”
5 inch o
utlet
redu
ce by 2
”
Always by 8”
thick
6 inch o
utlet
redu
ce by 3
”
N.B.: Th
e main duct must be reduce
d
ev
er
y 2 outlets.
Ducts specifications (heat)
Dimension
s
Length
Elbow
Average
equivalen
ce
4”
10’
1
x
90
o
Max 4,000 Btu
5”
10’
1
x
90
o
Max 6,000 Btu
6”
10’
1
x
90
o
Max 7,000 Btu
DAMPER
For a 4
” wa
rm air outlet: 2” x 10” damp
er
For a 5
” wa
rm air outlet: 2” x 12” damp
er or 4
” x 10”
For a 6
” wa
rm air outlet: 2” x 14” damp
er or 4
” x 12”
WARM AIR SYST
EM INSTALL
A
TION
HO
USE DIM
E
NSIONS
Example: 28 x 40 bungal
ow: 1,120 sq. ft.
28 x 40 x 8: 8
,960 cu. ft. x
1.8 Ch. air/hr:
16,128 Btu
Exposed w
al
ls:
40 + 40
+ 28
+ 28: 136 x 8: 1,088 cu. ft.
x 22:
23,936 Btu
Number o
f
w
indo
w
s:
12 of 3 x 4: 1
44 x 60:
8,640 Btu
Number o
f d
oors:
2 x 3 x 7: 42 x 100:
4,200 Btu
52,904 Btu
Non
-insulate
d basemen
t:
25%
Insulated b
asement:
1
5%
7,906 Btu
or 54 Btu pe
r sq. ft.
60,840 Btu
TO BE ADDE
D:
Hou
se 1 1/2
floor = 25%
Hou
se 2 floo
rs = 40%
BEDRO
OM (f
or exampl
e: 12 x 12)
12 x 12 x 8: 1
,152 cu. ft. x
1.8 Ch. air/hr:
2,074 Btu
Exposed w
al
ls:
12 + 12 x 8: 192 x 22:
4,224 Btu
Windo
w
s:
3 x 4 x 60
720 Btu
7,018
Btu
17
