Vermont Castings UVS27
Example:
A room that is 18' x 12' x 8' has a volume of 1728 cubic feet, ( length x width x height). 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 space volume is 3840 cubic feet. (1728 + 960 + 1152).
2.Divide the volume of space by 50 cubic feet. The result is the maximum BTU/Hr that the space can support.
Example:
3840 divided by 50 = 76.8 or 76,800 BTU/Hr.
3.Add the BTU/Hr ratings of all
Gas Water Heater | Gas Furnace |
Gas Fireplace Logs | Unvented Gas Heater |
Vented Gas Heater* | Other Gas Appliances* |
*Do not include Direct Vent appliances as these utilize outside air for combustion and vent to the outdoors.
Example:
Gas Range | 55,000 | BTU/Hr |
Unvented Heater | +33,000 | BTU/Hr |
Total | 88,000 | BTU/Hr |
4.Compare the maximum BTU/Hr rating the space can support with the total BTU/Hr used by the appliances.
Example:
76,800 BTU/Hr - max. the space can support
88,000 BTU/Hr - total used by appliances
In this example, the maximum BTU/Hr that the space can support is less than the total used by the appli- ances, the space is considered to be Confined space. Additional air must be provided to meet the require- ments of the Unvented heater.
A confined space may be ventilated in two ways:
A)Open up or provide at least two ventilating grilles to an adjoining unconfined space. Use any of the options illustrated in Figure 8.
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 located within 12" of the ceiling; the other within 12" of the floor. (If the total exceeds 100,000 BTU/Hr, additional grilles will be required.)
B)Vent the room directly to the outdoors. (Provide one square inch of opening for each 4,000 BTU/hr.
If the total BTU/Hr used by the appliances is less than the maximum BTU/Hr the space is able to support, the room meets the Unconfined space criteria and no further ventilation is required.
For further information on ventilation guidelines and sizing specifications follow the National Fuel Gas Code NFPA 54/ANSI Z223.1 Section 5.3.
W A R N I N G
This heater shall not be installed in a confined space or unusually tight construction unless provisions are made for adequate combustion and ventilation air.
W A R N I N G
If the area in which the heater may be operated is smaller than that defined as an unconfined spaceof if the building is of unusually tight constructins, provide adequate combustion and ventilation air by one of the methods described in the National Fuel Gas Code, ANSI Z223.1, NFPA 54, Section 5.3 or applicable codes.
Option 1 Vents to Adjoining Room
12”
Option 3 -
Vents to
Adjoining
Room
Option 2 - |
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Remove |
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Door to | 12” | |
Adjoining | ||
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Rooms |
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Fig. 8 Vent options to provide additional air.
8 | 20005004 |
