DOMINATOR 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 hori-
zontal 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 ducts
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
300
75
484
100
645
300
1935
400
100
645
133
860
400
2581
600
150
968
200
1290
600
3871
750
188
1210
250
1613
750
4839
900
225
1452
300
1935
900
5806
1050
263
1694
350
2258
1050
6774
1350
338
2177
450
2903
1350
8710
1500
375
2419
500
3226
1500
9677
1950
488
3145
650
4194
1950
12,581
2100
525
3387
700
4516
2100
13,548
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 the same
outside wall which terminates the exhaust gases or
vertically through the roof, see Figures 4, 5, 6 & 7.
WARNING: Common intake air systems may be
used provided 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 fl exible aluminum pipe can be used for the intake
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
Silicone caulk.
The combustion air system MUST be
supported by the building structure not the boiler/
water heater.
Table 4 - Intake Air Pipe Sizing
Model Size
Pipe Diameter
in
mm
300 & 400
6
152
600 & 750
8
203
900 & 1050
10
254
1350 - 2100
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 Power 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.
