Filter
Top Products
Special offers from our partners!
Find Replacement BBQ Parts for 20,308 Models. Repair your BBQ today.
5
103573
OWNER’S MANUAL
AIR FOR
COMBUSTION AND
VENTILATION
Continued
DETERMINING FRESH-AIR FLOW FOR FIREPLACE LOCATION
Determining if You Have a Confined or Unconfined Space
Use this worksheet to determine if you have a confined or unconfined space.
Space: Includes the room in which you will install firebox plus any adjoining rooms with doorless 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 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 of
the 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 firebox ___________________Btu/Hr
Gas water heater* ___________________Btu/Hr
Gas furnace ___________________Btu/Hr
Vented gas heater ___________________Btu/Hr
Gas firebox logs ___________________Btu/Hr
Other gas appliances* + ___________________Btu/Hr
Total = ___________________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)
79,000 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 worksheet, 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 no
additional fresh air ventilation.
WARNING: If the area in which the firebox and gas log heater may be operated is smaller than that defined as an
unconfined space or if the building is of unusually tight construction, provide adequate combustion and ventilation air
by one of the methods described in the
National Fuel Gas Code, ANS Z223.1, 1992, Section 5.3
or applicable local codes.
Example:
Gas water heater 40,000 Btu/Hr
Vent-free firebox with log heater + 39,000 Btu/Hr
Total = 79,000 Btu/Hr
Continued