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Confined Space Installation
NOTE: A confined
space is defined
as an area with less than 50
cubic feet(l.4m
3) per 1,000
BTUH
input rating
for all gas ap-
pliances installed
in the area.
Requirements
1.
Provide
confined
space with sufficient
air for proper com-
bustion
and ventilation
of flue gases
using horizontal
or
vertical
ducts or openings.
2.
Figure
11 illustrates
how to provide
combustion and ven-
tilation air. A minimum
of two permanent
openings,
one in-
let and one outlet,
are required.
3.
One opening
MUST be within 12" (300mm) ofthe floor and
the second
opening
within
12" (300mm)
of the ceiling.
4.
Size openings
and ducts per Table
2.
5.
Horizontal
duct openings
require 1" square
(25sq. mm) of
free area per 2,000 BTUH of combined
input for all gas ap-
pliances in area (see
Table 2).
6.
Vertica! duct openings
or openings
directly
to outside
re-
quire I square
(6.5mm 3) of free area per 4,000 BTUH for
combined
input of all gas appliances
in area (see Table 2).
Free Area
Minimum FreeAreaRequiredforEachOpening
BTUH
Round
Input
Ho_ontsl Duct
Ved_al Ductor openings
Duct
Rating
(2,000RTUH)
to outside
(4,000BTUH)
(4,000
BTUH)
50,000
25 sq. in.(161cm.2)
12.5sq. in.(81cm.2)
4"
75,000
35.5sq. in.(242cm. 2 )
18.75sq. in.(121crn. 2 )
5"
100,000
50 sq. in.(323cm. 2 )
25 sq. in.(161cm.2 )
6"
125,000
62.5sq. in.(403cm. 2 )
31.25sq. in.(202cm.2)
7"
150,000
71 eq. in.(484cm. 2 )
37.5 sq. in.(242cm.2)
7"
EXAMPLE: Determining F reeArea
Appliance I
Appliance 2
Total Input
100,000 + 30,000 = (130,000 + 4,000) = 210 cm,2
(32.5 Sq. In.) Vertical
Appliance 1 Appliance 2
Total Input
100,000 + 30,000 = (130,000 + 2,000) = 419 cm,2
(65 Sq. In.) Horizontal
Outside Air (This is ONLY a guide. Subject to codes of country having jurisdiction.)
This Installation
NOT approved in Canada
t
Gas Vent
. Gable V ent)
.1"
.=fAir(l)
MinimumOneInletand OneOutlnt A ir SupplyisRequl_d
Maybe in andCombination Shown
inlntA_ OpeningM_t be Withle12"(30Omm) offloor
O_t
Air OpeningMuntbe W_hin12"(_Omm)of €_lleg
(1) t Squue Inch (ecm_ p_ 4oo0BTUR
GasVent
Gable t /eat
f
_
I _'
,1o
i ,n,nt
Air(1)
nt
(2) 1 Squ_
Inch (6cm 2) p_ 2000 B]IJH
Unconfined Space Installation
feet(1.4m 3) per t ,000 Btuh total input rating for all gas appliances in area.
Refer to Table 3 for minimum area required,
Poison carbon monoxide gas hazard.
Most homes will require additional air,
An unconfined
space
or homes with tight
construction may not have adequate air infiltra-
tion for proper combustion and ventilation of flue
gases.
Failure to supply additional air by means of ven-
tilation grilles or ducts could result in personal in-
jury and/or death.
An unconfined space is defined as an area having a minimum volume of
50 cubic feet(1,4m 3) per 1,000 Btuh total input rating for all gas ap-
pliances in area. Refer to Table 3 for minimum area required.An uncon-
fined space is defined as an area havin_ a minimum volume of 50 cubic
BTUH Input
Rating
50,000
78,000
114,000
155,000
Minimum Area in
Square Feet
312(29m 2)
490(46m 2)
712(66m 2)
g68(90m 2)
Round Duct Size
1 Sq. inch
per 4,000 BTUH
4" (100mm)
5" (127mm)
6" (152rnm)
6" (178mm)
EXAMPLE:
NOTE: Square feet is based on 8 foot ceilings.
28000BTUH
X 50CubicFt.
=
1,400
= 175Sq. Ft.
1,000
8' Ceiling Height
NOTE:
Refer
to definitions
in section
titled Unusually
Tight
Construction.
If any one ofthe conditions apply, the space MUST
be considered
confined space regardless of size.
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