Duct System Quick Sizing Table
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document.xls 03/13/2022 DUCT SYSTEM QUICK SIZING TABLES Air Flow Flex Metal RD Equivalent Rectangular Round Duct Square CFM Duct Round Metal Duct Sizes Inch Equialency 80 6 5 Size SQ. IN. 120 7 6 or 3.5 x 10 5 20 160 8 7 6 28 175 8 8 or 3.5 x 14 (Stud Cavity) 7 38 200 9 8 or 6 x 8 8 50 300 10 9 or 8 x 8 9 64 1 400 11 10 or 10 x 8 (14 x 8 Panned Joist) 10 79 500 12 11 or 14 x 8 10 x 10 12 113 1.5 600 13 12 or 16 x 8 12 x 10 14 154 700 14 13 or 16 x 8 14 x 10 12 x 12 16 201 2 800 15 13 or 18 x 8 16 x 10 12 x 12 18 254 2.5 1000 16 14 or 22 x 8 18 x 10 14 x 12 20 314 3 1200 17 15 or 26 x 8 20 x 10 16 x 12 22 380 3.5 1400 18 16 or 30 x 8 22 x 10 18 x 12 24 452 4 1600 20 17 or 32 x 8 24 x 10 20 x 12 26 531 1800 20 18 or 28 x 10 22 x 12 28 616 5 2000 21 18 or 30 x 10 24 x 12 30 707 NON - FILTER GRILLE FILTER GRILLE 300 CFM per sq ft Gross Grill area 200 CFM per sq ft Gross Grill area Ton CFM Ton CFM 1.5 600 2.0 288 1.5 600 3 432 2 800 2.7 384 2 800 4 576 2.5 1000 3.3 480 2.5 1000 5 720 3 1200 4.0 576 3 1200 6 864 3.5 1400 4.7 672 3.5 1400 7 1008 4 1600 5.3 768 4 1600 8 1152 (Doug Garrett Building Performance & Comfort) Common Grille Sizes (GROSS SQUARE INCHES) 16 x 20 16 x 25 20 x 20 20 x 24 20 x 25 20 x 30 24 x 24 24 x 30 30 x 14 320 400 400 480 500 600 576 720 420 INPUT BTUS SQ IN Ducts Needed INPUT BTUS SQ IN Ducts Needed Supply and Return Supply and Return 40,000 80 18,000 108 60,000 120 24,000 144 80,000 160 30,000 180 100,000 200 36,000 216 120,000 240 42,000 252 140,000 280 48,000 288 (DELTA-T INC, Gas Furn & AC CHARTS) *Duct Size Calculated at 0.1 inches of available static pressure for each 100 Equivalent Feet of Duct System. Gross Sq Ft Gross Sq inches Gross Sq Ft Gross Sq inches GAS FURNACE (2 SQ. IN. PER 1,000 BTU's) AIR CONDITIONER (6 SQ. IN. PER 1,000 BTU's)
Transcript of Duct System Quick Sizing Table
Duct SizingDUCT SYSTEM QUICK SIZING TABLESAir FlowFlexMetal RDEquivalent RectangularRound Duct SquareCFMDuctRoundMetal Duct SizesInch Equialency8065SizeSQ. IN.12076or3.5 x 105201608762817588or3.5 x 14(Stud Cavity)73820098or6 x 8850300109or8 x 896414001110or10 x 8(14 x 8 Panned Joist)10795001211or14 x 810 x 10121131.56001312or16 x 812 x 10141547001413or16 x 814 x 1012 x 121620128001513or18 x 816 x 1012 x 12182542.510001614or22 x 818 x 1014 x 1220314312001715or26 x 820 x 1016 x 12223803.514001816or30 x 822 x 1018 x 1224452416002017or32 x 824 x 1020 x 122653118002018or28 x 1022 x 1228616520002118or30 x 1024 x 1230707*Duct Size Calculated at 0.1 inches of available static pressure for each 100 Equivalent Feet of Duct System.NON - FILTER GRILLEFILTER GRILLE300CFM per sq ft Gross Grill area200CFM per sq ft Gross Grill areaTonCFMGrossSq FtGrossSq inchesTonCFMGrossSq FtGrossSq inches1.56002.02881.5600343228002.7384280045762.510003.34802.510005720312004.05763120068643.514004.76723.5140071008416005.37684160081152(Doug Garrett Building Performance & Comfort)Common Grille Sizes (GROSS SQUARE INCHES)16 x 2016 x 2520 x 2020 x 2420 x 2520 x 3024 x 2424 x 3030 x 14320400400480500600576720420GAS FURNACE (2 SQ. IN. PER 1,000 BTU's)AIR CONDITIONER (6 SQ. IN. PER 1,000 BTU's)INPUT BTUSSQ IN Ducts NeededINPUT BTUSSQ IN Ducts NeededSupply and ReturnSupply and Return40,0008018,00010860,00012024,00014480,00016030,000180100,00020036,000216120,00024042,000252140,00028048,000288(DELTA-T INC, Gas Furn & AC CHARTS)51000.75133.3333333333
&R &F &D
Combustion Air
Gas Venting RequirementsHEATING UNIT TYPEOxygenNet StackTemperatureSmoke Test(CO) Carbon Monoxide Max ppmGAS (Natural Gas, Propane) atmosheric4% - 9%300-600 FN/A100Fan Assisted4% - 9%300-480 FN/A100CondensingPMIPMIN/A100Space Heaters5% - 15%300-650 FN/A100Standard Power Burner4% - 9%275-550 FN/A100HEATING UNIT TYPEDraft Gauge Probe PlacementWorst Case Acceptable Draft Readingsat Listed Outdoor TemperaturesGas Atmospheric AppliancesFlue After Draft Diverter< 2121-4041-6061-80> 80Gas Fan-assisted Appliances & Power Burners- 5Pa- 4Pa- 3Pa- 2Pa- 1PaGas Boilers- .02- .016- .012- .008- .004"w.c."w.c."w.c."w.c."w.c.
