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121623-01A
8
AIR FOR cOmBUSTION AND VENTILATION
Continued
.
Example:
35,840 Btu/Hr (maximum the
space.can.support)
40,000 Btu/Hr (actual amount of
Btu/Hr.used)
The space in the example is a confined space
because.the.actual.Btu/Hr.used.is.more.than.the.
maximum. Btu/Hr. the. space. can. support.. You.
must. provide. additional. fresh. air..Your. options.
are.as.follows:
A. Rework worksheet, adding the space of an
adjoining.room..If.the.extra.space.provides.an.
unconfined space, remove door to adjoining
room.or.add.ventilation.grills.between.rooms..
See.
Ventilation Air From Inside Building
.
B.. Vent. room. directly. to. the. outdoors.. See.
Ventilation Air From Outdoors,
page.9.
C. Install a lower Btu/Hr fireplace, if lower Btu/Hr
size makes room unconfined.
If.the.actual.Btu/Hr.used.is.less.than.the.maximum.
Btu/Hr the space can support,
the. space. is. an.
unconfined space. You will need no additional
fresh.air.ventilation.
WARNING: If the area in which
the heater may be operated is
smaller than that defined as
an unconfined space or if the
building is of unusually tight
construction, provide adequate
combustion and ventilation air
by one of the methods described
in the
National Fuel Gas Code,
ANSI Z223.1/NFPA 54
or appli
-
cable local codes.
VENTILATION AIR
Ventilation Air From Inside building
This.fresh.air.would.come.from.an.adjoining.
unconfined space. When ventilating to an
adjoining unconfined space, you must provide
two.permanent.openings:.one.within.12".of.the.
ceiling and one within 12" of the floor on the
wall.connecting.the.two.spaces.(see.options.
1 and 2, Figure 4 on page 9). You can also
remove.door.into.adjoining.room.(see.option.
3, Figure 4 on page 9). Follow the
National
Fuel Gas Code, ANSI Z223.1/NFPA 54, Air
for Combustion and Ventilation
for required
size of ventilation grills or ducts.
30,000
10,000
40,000
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.
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 16 ft. (length) x 14 ft.
(width).x.8.ft..(ceiling.height).=.1792.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:
.1792.cu..ft..(volume.of.space).x.20.
= 35,840 (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
.
*.Do.not.include.direct-vent.gas.appliances..
Direct-vent. draws. combustion. air. from. the.
outdoors.and.vents.to.the.outdoors.
.
Example:
.
Gas.water.heater.
. ._________ Btu/Hr
Vent-free fireplace
+
._________ Btu/Hr
.
Total.
=.._________ Btu/Hr
4.. Compare. the. maximum. Btu/Hr. the. space.
can.support.with.the.actual.amount.of.Btu/Hr.
used.
.
. ______ Btu/Hr. (maximum. the. space. can.
support).
.
._______ Btu/Hr.(actual.amount.of.Btu/Hr.used)
