Desa SVYD18NRA/PRA SERIES Owner's Operation And Installation Manual

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www.desatech.com 113084-01A6Unusually Tight ConstructionThe air that leaks around doors and windows mayprovide enough fresh air for combustion and ven-tilation. However, in buildings of unusually tightconstruction, you must provide additional 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 )or less with openings gasketed orsealed andb. weather stripping has been added onopenable windows and doors andc. caulking or sealants are applied to ar-eas such as joints around window anddoor frames, between sole plates andfloors, between wall-ceiling joints, be-tween wall panels, at penetrations forplumbing, electrical, and gas lines, andat other openings.If your home meets all of these three crite-ria, you must provide additional fresh air.SeeVentilation Air From Outdoors, page 7.If your home does not meet all of the threecriteria above, proceed toDeterminingFresh-Air Flow For Fireplace Location,column 2.Confined and Unconfined SpaceThe National Fuel Gas Code, ANSI Z223.1/NFPA54 defines a confined space as a space whose vol-ume is less than 50 cubic feet per 1,000 Btu perhour (4.8 m3 per kw) of the aggregate input ratingof all appliances installed in that space and an un-confined space as a space whose volume is not lessthan 50 cubic feet per 1,000 Btu per hour (4.8 m3per kw) of the aggregate input rating of all appli-ances installed in that space. Rooms communicat-ing directly with the space in which the appliancesare installed*, through openings not furnished withdoors, are considered a part of the unconfined space.* Adjoining rooms are communicating only if thereare doorless passageways or ventilation grills be-tween them.AIR FOR COMBUSTIONAND VENTILATIONContinuedDETERMINING FRESH-AIR FLOWFOR HEATER LOCATIONDetermining if You Have a Confined orUnconfined SpaceUse this work sheet to determine if you have aconfined or unconfined space.Space: Includes the room in which you will installfireplace plus any adjoining rooms with doorless pas-sageways or ventilation grills between the rooms.1. Determine the volume of the space (length xwidth x height).Length x Width x Height =__________cu. ft.(volume of space)Example: Space size 20 ft. (length) x 16 ft.(width) x 8 ft. (ceiling height) = 2560 cu. ft. (vol-ume of space)If additional ventilation to adjoining room is sup-plied with grills or openings, add the volume ofthese rooms to the total volume of the space.2. Multiply the space volume by 20 to determinethe maximum Btu/Hr the space can support.__________ (volume of space) x 20 = (Maxi-mum Btu/Hr the space can support)Example: 2560 cu. ft. (volume of space) x 20 =51,200 (maximum Btu/Hr the space can support)3. Add the Btu/Hr of all fuel burning appliances inthe space.Vent-free fireplace __________ Btu/HrGas water heater* __________ Btu/HrGas furnace __________ Btu/HrVented gas heater __________ Btu/HrGas fireplace logs __________ Btu/HrOther gas appliances* + __________ Btu/HrTotal = __________ Btu/Hr* Do not include direct-vent gas appliances. Di-rect-vent draws combustion air from the outdoorsand vents to the outdoors.Example:Gas water heater ______________ Btu/HrVent-free fireplace ______________ Btu/HrTotal ______________ Btu/Hr4. Compare the maximum Btu/Hr the space cansupport with the actual amount of Btu/Hr used.________ Btu/Hr (maximum the space can support)________ Btu/Hr (actual amount of Btu/Hr used)Example: 51,200 Btu/Hr (maximum the spacecan support)70,000 Btu/Hr (actual amount ofBtu/Hr used)The space in the above example is a confined spacebecause the actual Btu/Hr used is more than the maxi-mum Btu/Hr the space can support. You must pro-vide additional fresh air. Your options are as follows:40,000+ 30,000= 70,000