5104887OWNER’S MANUALAIR FORCOMBUSTION ANDVENTILATIONContinuedDETERMINING FRESH-AIR FLOW FOR FIREPLACE LOCATIONDetermining if You Have a Confined or Unconfined SpaceUse this work sheet to determine if you have a confined or unconfined space.Space: Includes the room in which you will install fireplace plus any adjoining rooms with doorless passageways or ventilation grillsbetween the rooms.1. Determine the volume of the space (length x width x height).Length x Width x Height = _________________ cu. ft. (volume of space)Example: Space size 22 ft. (length) x 18 ft. (width) x 8 ft. (ceiling height) = 3168 cu. ft. (volume of space)If additional ventilation to adjoining room is supplied with grills or openings, add the volume of these rooms to the total volume ofthe space.2. Divide the space volume by 50 cubic feet to determine the maximum Btu/Hr the space can support._________________ (volume of space) ÷ 50 cu. ft. = (Maximum Btu/Hr the space can support)Example: 3168 cu. ft. (volume of space) ÷ 50 cu. ft. = 63.3 or 63,300 (maximum Btu/Hr the space can support)3. Add the Btu/Hr of all fuel burning appliances in the 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. Direct-vent draws combustion air from the outdoors and vents to the outdoors.4. Compare the maximum Btu/Hr the space can support with the actual amount of Btu/Hr used._________________ Btu/Hr (maximum the space can support)_________________ Btu/Hr (actual amount of Btu/Hr used)Example: 63,300 Btu/Hr (maximum the space can support)73,000 Btu/Hr (actual amount of Btu/Hr used)The space in the above example is a confined space because the actual Btu/Hr used is more than the maximum Btu/Hr the space can support.You must provide additional fresh air. Your options are as follows:A. Rework work sheet, adding the space of an adjoining room. If the extra space provides an unconfined space, remove door to adjoin-ing room or add ventilation grills between rooms. See Ventilation Air from Inside Building, page 6.B. Vent room directly to the outdoors. See Ventilation Air from Outdoors, page 6.C. Install a lower Btu/Hr fireplace, if lower Btu/Hr size makes room unconfined.If the actual Btu/Hr used is less than the maximum Btu/Hr the space can support, the space is an unconfined space. You will need noadditional fresh air ventilation.ContinuedExample:Gas water heater 40,000 Btu/HrVent-free fireplace + 33,000 Btu/HrTotal = 73,000 Btu/HrWARNING: If the area in which the heater may be operated is smaller than that defined as an unconfined spaceor if the building is of unusually tight construction, provide adequate combustion and ventilation air by one ofthe methods described in theNational Fuel Gas Code, ANS Z223.1, 1992, Section 5.3 or applicable local codes.