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127119-01C
6
AIR FOR COMBUSTION AND VENTILATION
WARNING: This heater shall not be installed in a
room or space unless the required volume of indoor
combustion air is provided by the method described in
the National Fuel Gas Code, ANSI Z223.1/NFPA 54, the
International Fuel Gas Code, or applicable local codes.
Read the following instructions to ensure proper fresh air
for this and other fuel-burning appliances in your home.
Today’s homes are built more energy effi cient than ever. New materi-
als, increased insulation and new construction methods help reduce
heat loss in homes. Homeowners apply weather strip and caulk
around windows and doors to keep the cold air out and the warm
air in. During heating months, homeowners want their homes as
airtight as possible.
While it is good to make your home energy effi cient, your home needs
to breathe. Fresh air must enter your home. All fuel-burning appliances
need fresh air for proper combustion and ventilation.
Exhaust fans, some fi replaces, clothes dryers and some fuel-
burning appliances draw air from the house to operate. You must
provide adequate fresh air for these appliances. This will ensure
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
classifi cations:
1. Unusually Tight Construction
2. Unconfi ned Space
3. Confi ned Space.
The information on
Pages 6 through 7
will help you classify your
space and provide adequate ventilation.
Unusually Tight Construction
The air that leaks around doors and windows may provide enough
fresh air for combustion and ventilation. However, in buildings of
unusually tight construction, you must provide additional fresh air.
Unusually tight construction is defi ned as construction where:
a. walls and ceilings exposed to the outside atmosphere have a
continuous water vapor retarder with a rating of one perm (6 x
10
-11
kg per pa-sec-m
2
) or less with openings gasketed or sealed
and
b. weather stripping has been added on openable windows and
doors and
c. caulking or sealants are applied to areas such as joints around
window and door frames, between sole plates and fl oors, be-
tween wall-ceiling joints, between wall panels, at penetrations
for plumbing, electrical and gas lines and at other openings.
If your home meets all of the three criteria above, you must provide
additional fresh air. See Ventilation Air From Outdoors,
Page 7
.
If your home does not meet all of the three criteria above, proceed to
Determining Fresh-Air Flow for Heater Location.
Confi ned and Unconfi ned Space
The National Fuel Gas Code, ANSI Z223.1/ NFPA54 allows two
methods for determining whether the space in which the heater
is being installed is confi ned or unconfi ned space. The standard
method defi nes a confi ned space as a space whose volume is less
than 50 cubic feet per 1,000 Btu per hour (4.8 m3 per kw) of the
aggregate input rating of all appliances installed in that space and
an unconfi ned space as a space whose volume is not less than 50
cubic feet per 1,000 Btu per hour (4.8 m3 per kw) of the aggre-
gate 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 unconfi ned space.
Where the air infi ltration rate of a structure is known, the Known
Air Infi ltration Rate Method may be used. Follow The National Fuel
Gas Code, ANSI Z223.1/NFPA 54 to use this method to determine
if the space is confi ned or unconfi ned.
* Adjoining rooms are communicating only if there are doorless
passageways or ventilation grills between them.
DETERMINING FRESH-AIR FLOW FOR HEATER LOCATION
Determining if You Have a Confi ned or Unconfi ned Space Using
the Standard Method
Use this work sheet to determine if you have a confi ned or uncon-
fi ned space.
Space: Includes the room in which you will install fi replace 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. Multiply the space volume by 20 to determine the maximum Btu/Hr
the space can support.
_______ (volume of space) x 20 = (Maximum Btu/Hr the space
can support)
Example: 3168 cu. ft. (volume of space) x 20 = 63,360 (maximum
Btu/Hr the space can support)
3. Add the Btu/Hr of all fuel burning appliances in the space.
Vent-free fi replace ________Btu/Hr
Gas water heater* ________Btu/Hr
Gas
furnace
________Btu/Hr
Vented gas heater ________Btu/Hr
Gas fi replace logs ________Btu/Hr
Other gas appliances* + ____Btu/Hr
Tota
=_______Btu/Hr
* Do not include direct-vent gas appliances. Direct-vent draws
combustion air from the outdoors and vents to the outdoors.
Example:
Gas water heater ________Btu/Hr
Vent-free fi replace +_______Btu/Hr
Total
=_______Btu/Hr
40,000
33,000
73,000
