Desa LDL3924NR Owner's Operation And Installation Manual page 6

AIR FOR COMbUSTION
AND VENTILATION
Continued
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
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,
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
The National Fuel Gas Code, ANSI Z223.1/
NFPA 54 defines a confined space as a space
whose.volume.is.lessa.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
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 un-
confined space.
*.Adjoining.rooms.are.communicating.only.if.
there.are.doorless.passageways.or.ventilation.
grills.between.them.
6
kg per pa-sec-m
-11
.per.kw).of.the.ag-
3
.per.kw).
3
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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.
. Includes. the. room. in. which. you. will.
Space:
install.heater.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)
) or
2 . Example: Space size 20 ft. (length) x 16
ft..(width).x.8.ft..(ceiling.height).=.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..
.. Multiply.the.space.volume.by.0.to.deter-
mine.the.maximum.Btu/Hr.the.space.can.
support.
. . ___________ . (volume. of. space). x. 0.
=.(Maximum.Btu/Hr.the.space.can.sup-
port)
. Example:.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. appli-
ances.in.the.space.
. Vent-free.heater.
. Gas.water.heater*. . _________ Btu/Hr
. Gas.furnace.
. Vented.gas.heater. . _________ Btu/Hr
Gas fireplace logs . _________ Btu/Hr
. Other.gas.appliances*._____________+.
Btu/Hr
. Total.
. *. Do. not. include. direct-vent. gas. appli-
ances.. Direct-vent. draws. combustion.
air. from. the. outdoors. and. vents. to. the.
outdoors.
Example:
. Gas.water.heater. . _________ Btu/Hr
. Vent-free.heater.
. Total.
4.. Compare.the.maximum.Btu/Hr.the.space.
can. support. with. the. actual. amount. of.
Btu/Hr.used.
. _________ Btu/Hr
. _________ Btu/Hr
=. ________ Btu/Hr
40,000
33,000
+. ________ Btu/Hr
73,000
=. ________ Btu/Hr
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