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Manafacture: Gas-Fired Products File size: 368.47 kb File name: Language of manual:

1. Determine the volume of space (length x width x height). Include adjoining rooms connected by doorless passageways or ventilating grilles. Example: A room that is 18’ x 12’ x 8’ has a volume of 1728 cubic feet. An adjoining open kitchen that is 10’ x 12’ x 8’ has a volume of 960 cubic feet. An adjoining open dining room is 12’ x 12’ x 8’ with a volume of 1152 cubic feet. The total volume is 3840 feet. (1728 + 960 + 1152) 2. Divide the volume of space by 50 cubic feet. The result is the maximum BTU/hour the space can support. Example: 3840 cubic feet divided by 50 = 76.8 or 76,800 BTU/hour. 3. Add the BTU/hour ratings of all fuel-burning appliances installed in the same space, including the following: Gas Water Heater Gas Furnace Gas Fireplace Logs Vent-free Gas Heater Vented Gas Heater* Other Gas Appliances* *Do not include Direct-vent appliances as these use outdoor air for combustion and vent to the outdoors. Example: Gas Range 55,000 BTU/hour Vent-free Logset +25,000 BTU/hour Total 80,000 BTU/hour Vermont Castings Jefferson Vent Free Gas Heater 4. Compare the maximum BTU/hour rating the space can support with the total BTU/hour used by the appliances. Example: 76,800 BTU/hour the space can support 80,000 BTU/hour used by appliances In this example, the maximum BTU/hour that the space can support is less than the total used by the appliances. The space is considered to be Confined Space. Additional air must be provided to meet the requirements of the vent-free heater. A confined space may be ventilated in two ways: A. Open or provide at least two ventilating grilles to an adjoining unconfined space. (Fig. 2) Each of the two grilles must provide an opening of at least 50 square inches, with all opening dimensions being at least 3”. One grille must be within 12” of the ceiling; the other within 12” of the floor. (If the total exceeds 100,000 BTU/hour, additional grilles will be needed.) B. Vent the room directly to the outdoors. (Provide one square inch of opening for each 4,000 BTU/hour) For further information on ventilation guidelines and sizing specifications, follow the National Fuel Gas Code/NFPA 54/ANSI Z223.1, Section 5.3. If the total BTU/hour used by the appliances is less than the maximum BTU/hr the space can support, the room meets the Unconfined Spacecriteria and no further ventilation is needed. WARNING This heater shall not be installed in a confined space unless provisions are made for adequate combustion and ventilation air. WARNING If the area in which the heater may be operated is smaller than that defined as an unconfined space, provide adequate combustion and ventilation air by one of the methods described in the National Fuel Gas Code, ANSI Z223.1, 1992 Section 5.3. Option 1 - Vents to Adjoining Rooms Option 3 - Vents to Adjoining Room Option 2 - Remove Door to Adjoining Room VO370-2 Fig. 5 Supplementing ventilation air. Wall 10” 12” 8” 6” 4” 2” 10” 8” 6” 4” 2” 1” Wall 10” 12” 8” 6” 4” 2” 10” 8” 6” 4” 2” 1” Vermont Castin...

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