www.desatech.com
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6
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, fireplaces, 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, 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 5 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 un
-
usually tight construction, 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 7.
If your home does not meet all of the three
criteria above, proceed to
Determining
Fresh-Air Flow for Heater Location
.
Confined and Unconfined Space
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/
hr (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/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 unconfined space.
* 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 Confined or
Unconfined Space
Use this work sheet to determine if you have
a confined or unconfined space.
Space:
Includes the room in which you will install
fireplace plus any adjoining rooms with door
-
less 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) = 2,560 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:
2,560 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 fireplace
__________ Btu/Hr
Gas water heater*
__________ Btu/Hr
Gas furnace
__________ Btu/Hr
Vented gas heater
__________ Btu/Hr
Gas fireplace logs
__________ Btu/Hr
Other gas appliances* + _________ Btu/Hr
Total
= _________ Btu/Hr
AIR FOR COMbUSTION AND VENTILATION
Continued
