www.desatech.com
105604-01K
6
AIR FOR COMBUSTION
AND VENTILATION
warninG: this firebox shall
not be installed in a confined
space or unusually tight construc-
tion unless provisions are provid-
ed for adequate combustion and
ventilation air. read the following
instructions to insure proper fresh
air for this and other fuel-burning
appliances in your home.
Today’s homes are built more energy efficient
than ever. New materials, increased insulation and
new construction methods help reduce heat loss in
homes. Home owners weather strip and caulk around
windows and doors to keep the cold air out and the
warm air in. During heating months, home owners
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, fireboxes, clothes dryers and fuel
burning appliances draw air from the house to
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, Section 5.3, Air
for Combustion and Ventilation.
All spaces in homes fall into one of the three fol-
lowing ventilation classifications:
1. Unusually Tight Construction
2. Unconfined Space
3. Confined Space
The information on pages 6 through 8 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 ventila-
tion. However, in buildings of unusually tight con-
struction, you must provide additional fresh air.
unusually tight construction is defined as
construction where:
a. walls and ceilings exposed to the out-
side atmosphere have a continuous
water vapor retarder with a rating of
one perm (6x10
-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 floors, between 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 8.
If your home does not meet all of the three
criteria above, proceed to
Determining
Fresh-Air Flow For Firebox Location
,
page 7.
Confined space and unconfined space
The
National Fuel Gas Code ANSI Z223.1/NFPA
54
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 unconfined 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 com-
municating directly with the space in which the
appliances are installed*, through openings not
furnished with doors, are considered a part of the
unconfined space.
* Adjoining rooms are communicating only if
there are doorless passageways or ventilation grills
between them.
