12. DUCTS AND REGISTER MEASUREMENTS
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| (sample calculations) |
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| SIMPLIFIED METHOD |
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| WARM AIR SYSTEM INSTALLATION |
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| DISTRIBUTION SYSTEM |
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| Ducts size (heat) |
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| HOUSE DIMENSIONS |
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| Example: 28 x 40 bungalow: 1,120 sq. ft. |
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| 4 inch outlet | reduce by 1” |
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| 5 inch outlet | reduce by 2” | Always by 8” thick |
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| 28 x 40 x 8: 8,960 cu. ft. x 1.8 Ch. air/hr: | 16,128 Btu |
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| 6 inch outlet | reduce by 3” |
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| Exposed walls: |
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| N.B.: The main duct must | be reduced every 2 |
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| 40 + 40 + 28 + 28: 136 x 8: 1,088 cu. ft. x 22: | 23,936 Btu |
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| outlets. |
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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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| Ducts specifications (heat) |
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| Number of doors: |
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| Dimensions | Length Elbow | Average equivalence |
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| 2 x 3 x 7: 42 x 100: | 4,200 Btu |
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| 4” | 10’ | 1 x 90o | Max 4,000 Btu |
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| 5” | 10’ | 1 x 90o | Max 6,000 Btu |
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| 52,904 Btu |
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| 6” | 10’ | 1 x 90o | Max 7,000 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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| DAMPER |
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| FOR ELECTRIC ELEMENTS 80%:48,672 Btu or 14,28 kW |
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| TO BE ADDED:House 1 1/2 floor = 25% |
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| For a 4” warm air outlet: 2” x 10” damper |
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| House 2 floors = 40% |
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| For a 5” warm air outlet: 2” x 12” damper or 4” x 10” |
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| BEDROOM (for example: 12 x 12) |
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| For a 6” warm air outlet: 2” x 14” damper or 4” 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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