www.desatech.com111347-01F 7AIR FOR COMbUSTIONAND VENTILATIONContinuedFigure 3 - Ventilation Air from OutdoorsFigure 2 - Ventilation Air from InsideBuildingOutletAirVentilatedAtticOutletAirInletAirInlet Air VentilatedCrawl SpaceToCrawlSpaceTo AtticOrRemoveDoor intoAdjoiningRoom,Option3Ventilation GrillsInto Adjoining Room,Option 2VentilationGrills IntoAdjoiningRoom,Option 112"12"The space in the previous example is a confinedspace because the actual Btu/Hr used is more thanthe maximum Btu/Hr the space can support. Youmust provide additional fresh air. Your optionsare as follows:A. Rework worksheet, adding the space of anadjoining room. If the extra space provides anunconfined space, remove door to adjoiningroom or add ventilation grills between rooms.See Ventilation Air From Inside Building.B. Vent room directly to the outdoors. See Ven-tilation Air From Outdoors.C. Install a lower Btu/Hr fireplace, if lower Btu/Hrsize makes room unconfined.If the actual Btu/Hr used is less than the maxi-mum Btu/Hr the space can support, the space isan unconfined space. You will need no additionalfresh air ventilation.WARNING: If the area in whichthe heater may be operated issmaller than that defined asan unconfined space or if thebuilding is of unusually tightconstruction, provide adequatecombustion and ventilation airby one of the methods describedin the National Fuel Gas Code,ANSI Z223.1/NFPA 54 Section 5.3or applicable local codes.VENTILATION AIRVentilation Air From Inside BuildingThis fresh air would come from an adjoining un-confined space. When ventilating to an adjoiningunconfined space, you must provide two perma-nent openings: one within 12" of the ceiling andone within 12" of the floor on the wall connectingthe two spaces (see options 1 and 2, Figure 2). Youcan also remove door into adjoining room (seeoption 3, Figure 2). Follow the National Fuel GasCode, ANSI Z223.1/NFPA 54, Section 5.3, Air forCombustion and Ventilation for required size ofventilation grills or ducts.VENTILATION AIR FROMOUTDOORSProvide extra fresh air by using ventilation grills orducts. You must provide two permanent openings:one within 12" of the ceiling and one within 12"of the floor. Connect these items directly to theoutdoors or spaces open to the outdoors. Thesespaces include attics and crawl spaces. Follow theNational Fuel Gas Code, ANSI Z223.1/NFPA 54,Section 5.3, Air for Combustion and Ventilation forrequired size of ventilation grills or ducts.IMPORTANT: Do not provide openings for inletor outlet air into attic if attic has a thermostat-controlled power vent. Heated air entering the atticwill activate the power vent.