9.DUCTS AND DAMPERS DIMENSIONS (EXAMPLES OF CALCULATION)
SIMPLIFIED METHOD
DISTRIBUTION SYSTEM
Ducts size (heat) |
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4 inch outlet | reduce by 1” |
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5 inch outlet | reduce by 2” | Always by 8” thick |
6 inch outlet | reduce by 3” |
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N.B.: The main duct must be reduced every 2 outlets.
Ducts specifications (heat) |
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Dimensions | Length | Elbow | Average equivalence |
4” | 10’ | 1 x 90o | Max 4,000 Btu |
5” | 10’ | 1 x 90o | Max 6,000 Btu |
6” | 10’ | 1 x 90o | Max 7,000 Btu |
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: 1,120 sq. ft.
28 x 40 x 8: 8,960 cu. ft. x 1.8 Ch. air/hr: | 16,128 Btu |
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Exposed walls: |
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40 + 40 + 28 + 28: 136 x 8: 1,088 cu. ft. x 22: | 23,936 Btu |
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Number of windows: |
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12 of 3 x 4: 144 x 60: | 8,640 | Btu |
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Number of doors: |
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2 x 3 x 7: 42 x 100: | 4,200 | Btu |
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| 52,904 Btu |
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Insulated basement: 15% |
| 7,906 | Btu |
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or 54 Btu per sq. ft. |
| 60,840 Btu |
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TO BE ADDED:House 1 1/2 floor = 25% |
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House 2 floors = 40% |
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BEDROOM (for example: 12 x 12) |
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12 x 12 x 8: 1,152 cu. ft. x 1.8 Ch. air/hr: | 2,074 | Btu |
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Exposed walls: |
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12 + 12 x 8: 192 x 22: | 4,224 | Btu |
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Windows: |
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3 x 4 x 60 |
| 720 | Btu |
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| 7,018 | Btu |
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