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7 PART F - DUCTS AND DAMPERS DIMENSIONS
7.1 DUCTS AND DAMPERS DIMENSIONS (EXAMPLES OF CALCULATION)
SIMPLIFIED METHOD
DISTRIBUTION SYSTEM
Ducts size (heat)
4 inch outlet
reduce by 1"
5 inch outlet
reduce by 2"
6 inch outlet
reduce by 3"
Always by 8" thick
N.B.: The main duct must be reduced every
2 outlets.
Ducts specifications (heat)
Dimensions Length
Elbow
4"
10'
1 x 90
5"
10'
1 x 90
6"
10'
1 x 90
DAMPER
For a 4" warm air outlet: 2" x 10" damper
For a 5" warm air outlet: 2" x 12" damper
or 4" x 10"
For a 6" warm air outlet: 2" x 14" damper
or 4" x 12""
WARM AIR SYSTEM INSTALLATION
HOUSE DIMENSIONS
Example: 28 x 40 bungalow =
28 x 40 x 8 = 8,960 sq. ft.
x 1.8 Ch. air/hr:
Exposed walls :
40 + 40 + 28 + 28 = 136
x 8 = 1,088 sq. ft. x 22 =
Number of windows :
12 of 3 x 4 = 144 x 60 =
Average
Number of doors :
equivalence
2 x 3' x 7' = 42 x 100 =
o
Max 4,000 Btu
o
Max 6,000 Btu
o
Max 7,000 Btu
Non-insulated basement: 25 %
Insulated basement: 15 %
Or 54 Btu per sq. ft.
FOR ELECTRIC ELEMENTS 80% =
TO BE ADDED: House 1 1/2 floor = 25 %
BEDROOM (for example: 12 x 12)
12 x 12 x 8 = 1,152 sq. ft.
x 1.8 Ch. air/h =
Exposed walls:
12 + 12 x 8 : 192 x 22 =
Windows:
3 x 4 x 60 =
59
1,120 sq. ft.
16,128 Btu
23,936 Btu
8,640 Btu
4,200 Btu
52,904 Btu
7,906 Btu
60,840 Btu
48,672 Btu or 14,28 kW
House 2 floors
= 40 %
2,074 Btu
4,224 Btu
720 Btu
7
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