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AIR FOR COMbUSTION
AND VENTILATION
Continued
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 (6 x 10
kg per pa-sec-m
-11
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 plumb-
ing, 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 cri-
teria above, proceed to Determining Fresh-Air
Flow For Heater Location.
Confined and Unconfined Space
The National Fuel Gas Code, ANSI Z223.1/
NFPA 54 defines a confined space as a space
6
whose volume is less than 50 cubic feet per
1,000 Btu per hour (4.8 m
gregate 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
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 un-
confined space.
* Adjoining rooms are communicating only if
there are doorless passageways or ventilation
grills between them.
DETERMINING FRESH-AIR FLOW
FOR FIREpLACE 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
doorless passageways or ventilation grills be-
tween 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
) or less
2
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
Gas water heater*
Gas furnace
Vented gas heater
Gas fireplace logs
Other gas appliances* + ________ Btu/Hr
Total
* Do not include direct-vent gas appliances.
www.desatech.com
per kw) of the ag-
3
per kw) of
3
_________ Btu/Hr
_________ Btu/Hr
_________ Btu/Hr
_________ Btu/Hr
_________ Btu/Hr
= ________ Btu/Hr
121308-01E
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