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AIR FOR COMBUSTION AND VENTILATION
WARNING
: This heater
shall not be installed in a confined
space or unusually tight construc-
tion unless provisions are provided
for adequate combustion and ven-
tilation air. Read the following in-
structions to insure proper fresh
air for this andother fuel-burning
appliances in your home.
PROVIDING ADEQUATE
VENTILATION
The following are excerpts from
National Fuel Gas Code
,
NFPA 54/
ANSI Z223.1,Section 5.3
,
Air for
Combustion and Ventilation
.
All spaces in homes fall into one of
th e three follo wing ven tilation
classifications:
1. Unusually Tight Construction
2. Unconfined Space
3. Confined Space
The information on pages 5 through 6
will help you classify your space and
provide adequate ventilation.
Confined and Unconfined Space
The National Fuel Gas Code, ANSI
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 aggregate 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 installed
in that space. Rooms communicat-
ing directly with the space in which
the appliances are installed*, through
openings not furnished with doors,
are co nsid ered a p art of th e
unconfined space.
This heater shall not be installed in
a confined space or unusually tight
construction unless provisions are
provided for adequate combustion
and ventilation air.
* Adjoining rooms are communicat-
ing only if there are doorless pas-
sageways or ventilation grills be-
tween them.
Unusually Tight Construction
DETERMINING FRESH-AIR 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)=2560cu. 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)
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
p er p a- s ec -m
2
) o r les s w it h
openings gasketed or sealed
and
b) weather stripping has been added
on windows that can be opened
and doors
and
c) caulking or sealants are applied
to areas such as joints around
window and door frames, between
sole plates and floors, between
wall-ceiling joints, between wall
p a n e ls , a t p e n e t r a t io n s f o r
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 6)
.
If your home does not meet all of the
three c riteria ab ove, p ro ceed to
Determining Fresh-Air Flow For
Heater Location (below).
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