SuperiorFireplaces.US.com 900781-00_NC8
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 10-11 kg per pa-sec-m2) 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 three criteria above,
you must provide additional fresh air. See
Ventilation Air From Outdoors, Page 10.
Ifyour homedoes notmeet all three criteria
above, proceed to Determining Fresh-Air
Flow For Heater Location, Page 8.
Confined and Unconfined Space
The National Fuel Gas Code, ANSI Z223.1/
NFPA54 allows two methods for determining
whetherthespacein whichtheheateris being
installedisconfinedor unconfinedspace.The
standardmethoddefinesaconfinedspaceasa
space whose volume is less than 50 cubic feet
per1,000Btuperhour(4.8m3perkw)oftheag-
gregateinputratingofallappliancesinstalledin
thatspaceandanunconfinedspaceasaspace
whose volumeis not lessthan 50cubicfeetper
1,000 Btu per hour (4.8 m3per kw) of the ag-
gregateinputratingofallappliancesinstalledin
thatspace.Roomscommunicatingdirectlywith
thespaceinwhichtheappliancesareinstalled*,
through openings not furnished with doors, are
considered a part of the unconfined space.
Where the air infiltration rate of a structure is
known,theKnownAirInfiltrationRate Method
may be used. Follow The National Fuel Gas
Code, ANSI Z223.1/NFPA 54 to use this
method to determine if the space is confined
or unconfined.
* Adjoining rooms are communicating only if
therearedoorlesspassageways orventilation
grills between them.
DETERMINING FRESH-AIR FLOW
FOR FIREPLACE LOCATION
Determining if You Have a Confined or
Unconfined Space Using the Standard
Method
AIR FOR COMBUSTION AND VENTILATION
Today’s homes are built more energy efficient
thanever.Newmaterials,increasedinsulation,
and new construction methods help reduce
heat loss in homes. Homeowners apply
weather strip and caulk around windows and
doors to keepthecoldairoutandthewarmair
in. During heating months, homeowners want
their homes as airtight as possible.
While it is good to make your home energy
efficient, your home needs to breathe. Fresh
air must enter your home.All fuel-burning ap-
pliancesneedfreshairforpropercombustion
and ventilation.
Exhaust fans, some fireplaces, clothes dryers
and some fuel-burning appliances draw air
from the house to operate. You must provide
adequate fresh air for these appliances. This
will ensure proper venting of vented fuel-
burning appliances.
PROVIDING ADEQUATE
VENTILATION
ThefollowingareexcerptsfromNationalFuel
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 8–10 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.
WARNING: This heater shall not
be installed in a room or space un-
less the required volume of indoor
combustion air is provided by the
method described in the National
Fuel Gas Code, ANSI Z223.1/NFPA
54, the International Fuel Gas Code,
or applicable local codes. Read the
following instructions to ensure
properfresh air for thisand other fuel-
burning appliances in your home.
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