6100751FRESH AIRFORCOMBUSTIONANDVENTILATIONContinuedWARNING ICON G 001WARNINGYou must provide additional ventilation air in a confined space.DETERMINING FRESH-AIR FLOW FOR HEATER LOCATIONDetermining if You Have a Confined or Unconfined SpaceUse this worksheet to determine if you have a confined or unconfined space.Space: Includes the room in which you will install heater plus any adjoining rooms withdoorless passageways or ventilation grills between 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 20 ft. (length) x 16 ft. (width) x 8 ft. (ceiling height) =2560 cu. ft. (volume of space)If additional ventilation to adjoining room is supplied with grills or openings, add thevolume of these rooms to the total volume of the space.2. Divide the space volume by 50 cubic feet to determine the maximum BTU/Hr the spacecan support.____________ (volume of space) ÷ 50 cu. ft. = (Maximum BTU/Hrthe space can support)Example: 2560 cu. ft. (volume of space) ÷ 50 cu. ft. = 51.2 or 51,200 (maximumBTU/Hr the space can support)3. Add the BTU/Hr of all fuel burning appliances in the space.Vent-free heater ___________________ BTU/HrGas water heater* ___________________ BTU/HrGas furnace ___________________ BTU/HrVented gas heater ___________________ BTU/HrGas fireplace logs ___________________ BTU/HrOther gas appliances* + ___________________ BTU/HrTotal = ___________________ BTU/HrExample: Gas water heater 40,000 BTU/HrVent-free heater + 18,000 BTU/HrTotal = 58,000 BTU/Hr* Do not include direct-vent gas appliances. Direct-vent draws combustion air from theoutdoors 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: 51,200 BTU/Hr (maximum the space can support)58,000 BTU/Hr (actual amount of BTU/Hr used)The space in the above example is a confined space because the actual BTU/Hr used ismore than the maximum BTU/Hr the space can support. You must provide additional freshair. Your options are as follows:A. Rework worksheet, adding the space of an adjoining room. If the extra space providesan unconfined space, remove door to adjoining room or add ventilation grills betweenrooms. See Ventilation Air From Inside Building, page 7.B. Vent room directly to the outdoors. See Ventilation Air From Outdoors, page 8.C. Install a lower BTU/Hr heater, 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, thespace is an unconfined space. You will need no additional fresh air ventilation.