18100792AIR FORCOMBUSTIONANDVENTILATIONContinuedFigure 14 - Checking for Draft SpillageNo Draft Hood Spillage: This shows there is enough fresh air in area forappliances. Turn off all exhaust fans and appliances if desired.In the absence of local codes, use the following excerpts from the National FuelGas Code NFPA 54/ANSI Z223.1, Air for Combustion and Ventilation.DETERMINING FRESH-AIR FLOW FOR HEATER LOCATIONExample 1: Locating Heater in Unconfined (Open) AreaNOTICEAn unconfined area has a minimum air volume of 50cubic feet for each 1000 BTU/Hr input rating of allappliances in the area (cubic feet equals length x widthx height of area). Include adjoining rooms only if thereare no doors between the rooms or if you add ventila-tion grills between the rooms (seeVentilating ConfinedArea, page 20).In an open area, the air that leaks around doors and windows may provide enoughfresh air for combustion and ventilation.Draft Hood Spillage TestFollow the steps below to see if enough fresh air is available.1. Close all windows and doors.2. If you have a fireplace, start a fire. Build fire until flames are burning strongly.3. Turn on all exhaust fans. These include exhaust fans for kitchen, bathroom,water heaters (gas or electric), etc.4. Turn on all vented gas appliances. These include any room heaters, waterheaters, clothes dryer, etc.5. Wait ten minutes for drafts to regulate.6. Check for draft-hood spillage at each vented gas appliance. Do this by holdinga lit match two inches from the draft opening (see Figure 14). If match flamepulls toward the draft hood, there is no spillage. If match flame blows awayfrom the draft hood, there is spillage. This is a hazardous condition. See DraftHood Spillage, page 19.TypicalWaterHeaterMatchDraft HoodVent PipeHeaterMatchDraft HoodOpeningVent Pipe