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119505-01E 5
operate. You must provide adequate fresh air
for these appliances. This will insure proper
venting of vented fuel-burning appliances.
PROVIDING ADEQUATE
VENTILATION
The following are excerpts from National
Fuel Gas Code ANSI Z223.1/NFPA 54, Air
for Combustion and Ventilation.
All spaces in homes fall into one of the three
following ventilation classications:
1. Unusually Tight Construction
2. Unconned Space
3. Conned Space
The information on pages 4 through 6 will help
you classify your space and provide adequate
ventilation.
The air that leaks around doors and windows
may provide enough fresh air for combustion
and ventilation. However, in buildings of un-
usually tight construction, you must provide
additional fresh air.
construction where:
-
-11
2
) or less
and
and
If your home meets all of the three criteria
See Ventilation Air From Outdoors
If your home does not meet all of the three
Determining
Fresh-Air Flow For Firebox Location
The National Fuel Gas Code ANSI Z223.1/
NFPA 54 denes a conned space as a space
whose volume is less than 50 cubic feet per
1,000 Btu/hr (4.8 m
3
per kw) of the aggregate
input rating of all appliances installed in that
AIR FOR COMBUSTION AND VENTILATION
Continued
space and an unconned space as a space
whose volume is not less than 50 cubic feet per
1,000 Btu/hr (4.8 m
3
per kw) of the aggregate
input rating of all appliances installed in that
space. Rooms communicating directly with the
space in which the appliances are installed*,
through openings not furnished with doors, are
considered a part of the unconned space.
* Adjoining rooms are communicating only if
there are doorless passageways or ventilation
grills between them.
DETERMINING FRESH-AIR FLOW
FOR HEATER LOCATION
Use this work sheet to determine if you have
a conned or unconned space.
Includes the room in which you will
install heater 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 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 the
volume of these rooms to the total volume
of the space.
2. Multiply the space volume by 20 to determine
the maximum Btu/Hr the space can support.
________ (volume of space) x 20 = (Maxi-
mum Btu/Hr the space can support)
Example: 2560 cu. ft. (volume of space) x 20
= 51,200 (maximum Btu/Hr the space can
support)
3. Add the Btu/Hr of all fuel burning appliances
in the space.
Vent-free heater ___________Btu/Hr
Gas water heater* ___________Btu/Hr
Gas furnace ___________Btu/Hr
Vented gas heater ___________Btu/Hr
Gas replace 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.