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.