www.desatech.com119508-01B 7AIR FOR COMbUSTION AND VENTILATIONWARNING: This heater shallnot be installed in a room orspace unless the required vol-ume of indoor combustion airis provided by the method de-scribed in the National Fuel GasCode, ANSI Z223.1/NFPA 54, theInternational Fuel Gas Code, orapplicable local codes. Read thefollowing instructions to insureproper fresh air for this andother fuel-burning appliancesin your home.Today’s homes are built more energy efficientthan ever. New materials, increased insulationand new construction methods help reduceheat loss in homes. Home owners weatherstrip and caulk around windows and doorsto keep the cold air out and the warm air in.During heating months, home owners wanttheir homes as airtight as possible.While it is good to make your home energyefficient, your home needs to breathe. Freshair must enter your home. All fuel-burning ap-pliances need fresh air for proper combustionand ventilation.Exhaust fans, fireplaces, clothes dryers andfuel burning appliances draw air from thehouse to operate. You must provide adequatefresh air for these appliances. This will insureproper venting of vented fuel-burning appli-ances.PROVIDING ADEQUATEVENTILATIONThe following are excerpts from National FuelGas Code, ANSI Z223.1/NFPA 54, Air forCombustion and Ventilation.All spaces in homes fall into one of the threefollowing ventilation classifications:1. Unusually Tight Construction2. Unconfined Space3. Confined SpaceThe information on pages 7 through 9 will helpyou classify your space and provide adequateventilation.Unusually Tight ConstructionThe air that leaks around doors and windowsmay provide enough fresh air for combustionand ventilation. However, in buildings of un-usually tight construction, you must provideadditional fresh air.Unusually tight construction is defined asconstruction where:a. walls and ceilings exposed to the out-side atmosphere have a continuouswater vapor retarder with a rating ofone perm (6 x 10-11 kg per pa-sec-m2) orless with openings gasketed or sealedandb. weather stripping has been added onopenable windows and doors andc. caulking or sealants are applied toareas such as joints around windowand door frames, between sole platesand floors, between wall-ceiling joints,between wall panels, at penetrationsfor plumbing, electrical and gas linesand at other openings.If your home meets all of the three criteriaabove, you must provide additional fresh air.See Ventilation Air From Outdoors, page 9.If your home does not meet all of the threecriteria above, proceed to Determining Fresh-Air Flow For Fireplace Location, page 8.Confined and Unconfined SpaceThe National Fuel Gas Code, ANSI Z223.1/NFPA 54 defines a confined space as a spacewhose volume is less than 50 cubic feet per1,000 Btu/hr (4.8 m3 per kw) of the aggregateinput rating of all appliances installed in thatspace and an unconfined space as a spacewhose volume is not less than 50 cubic feetper 1,000 Btu/hr (4.8 m3 per kw) of the ag-gregate input rating of all appliances installedin that space. Rooms communicating directlywith the space in which the appliances areinstalled*, through openings not furnishedwith doors, are considered a part of the un-confined space.* Adjoining rooms are communicating only ifthere are doorless passageways or ventilationgrills between them.