4
AIR FOR COMBUSTION AND VENTILATION
WARNING:
This heater shall
not be installed in a confined space
or unusually tight construction
unless provisions are provided for
adequate combustion and ventila-
tion air. Read the following in-
structions to insure proper fresh
air for this and other fuel-burning
appliances in your home.
PROVIDING ADEQUATE
VENTILATION
The following are excerpts from
National Fuel Gas Code,
NFPA 54/
ANSZ 223.1.Section 5.3
, Air for
Combustion and Ventilation.
All spaces in homes fall into one
of the three following ventilation
classifications:
1. Unusually Tight Construction
2. Unconfined Space
3. Confined Space
The information on pages 4 through
5 will help you classify your space
and provide adequate ventilation.
Confined and Unconfined Space
The National Fuel Gas Code, ANS
Z223.1
defines a confined space as
a space whose volume is less
than 50 cubic feet per 1,000 Btu per
hour (4.8 m
3
per kw) of the aggre-
gate input rating of all appliances
installed in that space and an
unconfining space as a space
whose volume is not less than 50
cubic feet per 1,000 Btu per hour
(4.8 m
3
per kw) of the aggregate
input rating of all appliances in-
stalled in that space. Rooms com-
municating directly with the space
in which the appliances are
installed*, through openings not
furnished with doors, are consid-
ered a part of the unconfined
space.
This heater shall not be installed
in a confined space or unusually
tight construction unless provisions
are provided for adequate com-
bustion and ventilation air.
* Adjoining rooms are communi-
cating only if there are doorless
passageways or ventilation grills
between them.
Unusually Tight Construction
DETERMINING FRESHAIR FLOW FOR HEATER 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 heater plus any adjoining rooms with doorless passageways
or ventilation grills between the rooms.
1. Determine the volume of the space (length
×
width
×
height).
Length
×
Width
×
Height= cu.ft. (volume of space)
Example: Space size 20ft. (length)
×
16ft. ( width)
×
8ft. (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. 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: 2560 cu. ft. (volume of space)
÷
50 cu.ft. = 51.2 or 51,200 (maximum Btu/Hr the space can support)
AIR FOR COMBUSTION AND VENTILATION
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
defined 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
×
10
-11
kg per
pa-sec-m
2
) or less with openings
gasketed or sealed and
b) weather stripping has been
added on windows that open and
doors and
c) caulking or sealants are ap-
plied to areas such as joints around
window and door frames, between
sole plates and floors, between wall-
ceiling joints, between wall panels,
at penetrations f or plumbing,
electrical, and gas lines, and at other
openings.
If your home meets all of the
three criteria above, you must pro-
vide additional fresh air. See
Venti-
lation Air From Outdoors,
page 5
.
If your home does not meet all of the
three criteria above, proceed to
Determining Fresh-Air Flow For
Heater Location,
below
.