LCD INSTALLATION AND OPERATION INSTRUCTIONS
Page 6
All Air From Outside The Building
When installed in a confi ned space
without utilizing
the intake air option
two permanent openings
communicating directly with, or by ducts to, the outdoors
or spaces that freely communicate with the outdoors must
be present. The upper opening must be within
12 in
,
305 mm
of, but not less than
3 in
,
76 mm
from, the top of
the enclosure. The bottom opening must be within
12 in
,
305 mm
of, but not less than
3 in
,
76 mm
from, the bottom
of the enclosure.
Where directly communicating with the outdoors
or communicating with the outdoors through vertical
ducts, each opening shall have a minimum free area
of
1 in
2
/4000 Btu/hr
,
550 mm
2
/kW
of the total input
rating of all of the equipment in the enclosure.
Where communicating with the outdoors through
horizontal ducts, each opening shall have a minimum
free area of
1 in
2
/2000 Btu/hr
,
1100 mm
2
/kW
of the total
input rating of all of the equipment in the enclosure. When
louvers and screens are used, they must have the same
cross-sectional area as the free area of the opening to
which they connect.
When calculating the free area necessary to meet
the make-up air requirements of the enclosure,
consideration must be given to the blockage effects
of louvers, grills and screens. Screens must have a
minimum mesh size of
1/4 in
,
6.4mm
. If the free area
through a louver or grill is not known, ducts should be
sized per Table 3.
Table 3 - Make-up Air Louver Sizing
Required Cross Sectional Area
Input
1/4 in
6.4 mm
75% Free Area
25% Free Area
(MBH)
Wire Screen
Metal Louvers
Wooden Louvers
in
2
cm
2
in
2
cm
2
in
2
cm
2
225
57
363
75
484
225
1452
300
75
484
100
645
300
1935
399
100
645
133
858
399
2573
600
150
968
200
1290
600
3870
750
190
1210
250
1613
750
4840
1050
263
1696
350
2258
1050
6773
1200
300
1936
400
2580
1200
7740
1480
370
2388
494
3182
1480
9546
1650
413
2662
550
3548
1650
10,643
1970
493
3179
657
4236
1970
12,707
2300
575
3711
767
4945
2300
14,835
Canadian installations must comply with CSA B149.1
when
air supply
is provided by natural air fl ow from the
outdoors for
natural draft
, partial fan-assisted, fan-
assisted, or power draft-assisted
burners
, there shall
be a permanent
air supply
opening(s) having a cross-
sectional area of not less than
1 in
2
per
7,000 Btuh
(310 mm
2
per kW)
up to
and including
1 million Btuh,
plus
1 in
2
per 14,000 Btuh
(155 mm
2
per kW)
in excess
of
1 million Btuh
.
Intake Air Option - General Guidelines
This confi guration provides combustion air directly to the
boiler/water heater’s air intake using a dedicated pipe
to obtain combustion air from the outdoors. Combustion
air can be drawn in horizontally through an outside wall
or vertically through the roof, see Figures 4, 5, 6 & 7.
WARNING: Common intake air systems may
be used to provide the common duct is sized
properly and an intake combustion air damper
is installed in the intake air pipe of each heater.
Improper installation can result in excessive
levels of carbon monoxide which can cause
severe personal injury or death!
Single wall galvanized smoke pipe, single wall aluminum
pipe or flexible aluminum pipe can be used for the
in-take air pipe. It must be sized per Table 4. All joints
in metal combustion air systems must be secured using
corrosion resistant fasteners and sealed using a suitable
Silicon caulk or tape.
The combustion air system
MUST be supported by the building structure not
the boiler/water heater.
Table 4 - Combustion Air Pipe Sizing
Model Size
Pipe Diameter
in
mm
225 - 300
5
127
400
6
152
600 - 750
8
203
1050
10
254
1200 - 2300
12
305
CAUTION: A stack damper interlocked with the unit
should be installed in the intake air pipe when the
infi ltration of sub-freezing air could occur, otherwise
the unit could freeze up voiding the warranty!
Intake Air Option - Horizontal Guidelines
The maximum equivalent length for the horizontal
combustion air pipe on installations that used the Direct
Vent option is
35 ft
,
10.8 m
. The maximum equivalent
length for the horizontal combustion air pipe on
installations that use the Horizontal Vent option is
100 ft
,
30.5 m
. Each 90° elbow and the combustion air terminal
are equal to
10 linear ft
,
3.0
m
of pipe. If horizontal runs
exceed
5 ft,
1.5 m
they must be supported at
3 ft
,
0.9 m
intervals with overhead hangers. The certifi ed combustion
air terminal from RBI must be used and installed as
shown in Figures 4 and 5.
Intake Air Option - Vertical Guidelines
The maximum length for the vertical combustion air
pipe is
30 ft
,
9.1 m
plus two 90° elbows. A listed,
nonrestrictive combustion air cap must be used. The
combustion air cap must terminate as shown in Figure
6. The penetration point in the roof must be properly
fl ashed and sealed.
