Determine water heater location, Installation & service manual – Lochinvar Shield SNR150-100 User Manual
Page 13
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1
Determine water heater location
(continued)
Figure 1-6_Combustion Air from Outside - Single
Opening
3. If air is taken from another interior space, each of the
two
openings specified above should have a net free
area of one square inch for each 1000 Btu/hr (22 cm
2
per kW) of input, but not less than 100 square inches
(645
cm
2
) (see FIG. 1-5).
4. If a single combustion air opening is provided to bring
combustion air in directly from the outdoors, the opening
must be sized based on a minimum free area of one square
inch per 3000 Btu/hr (7 cm
2
per kW). This opening must
be located within 12" (30 cm) of the top of the enclosure
(see FIG. 1-6).
IF NECESSARY FOR
TIGHT CONSTRUCTION
Figure 1-5_Combustion Air from Interior Space
Installation & Service Manual
TM
TABLE - 1B
MINIMUM RECOMMENDED COMBUSTION
AIR SUPPLY TO EQUIPMENT ROOM
Model
Number
FIG. 1-3
FIG. 1-4
FIG. 1-5
FIG. 1-6
*Outside Air from
2 Openings Directly from
Outdoors
*Outside Air from
2 Ducts Delivered from
Outdoors
**Inside Air from
2 Ducts Delivered from Interior
Space
*Outside Air from
1 Opening Directly
from Outdoors, in
2
Top
Opening, in
2
Bottom
Opening, in
2
Top
Opening, in
2
Bottom
Opening, in
2
Top
Opening, in
2
Bottom
Opening, in
2
SNR150-100
38
(246 cm
2
)
38
(246 cm
2
)
75
(484 cm
2
)
75
(484 cm
2
)
150
(968 cm
2
)
150
(968 cm
2
)
50
(323 cm
2
)
SNR200-100
50
(323 cm
2
)
50
(323 cm
2
)
100
(646 cm
2
)
100
(646 cm
2
)
200
(1,291 cm
2
)
200
(1,291 cm
2
)
67
(433 cm
2
)
SNA285-125
72
(465 cm
2
)
72
(465 cm
2
)
143
(923 cm
2
)
143
(923 cm
2
)
285
(1,839 cm
2
)
285
(1,839 cm
2
)
95
(613 cm
2
)
SNA400-125
100
(646 cm
2
)
100
(646 cm
2
)
200
(1,291 cm
2
)
200
(1,291 cm
2
)
400
(2,581 cm
2
)
400
(2,581 cm
2
)
134
(865 cm
2
)
SNA500-125
125
(807 cm
2
)
125
(807 cm
2
)
250
(1,613 cm
2
)
250
(1,613 cm
2
)
500
(3,226 cm
2
)
500
(3,226 cm
2
)
167
(1,078 cm
2
)
*Outside air openings shall directly communicate with the outdoors. When combustion air is drawn from the outside through a
duct, the net free area of each of the two openings must have twice (2 times) the free area required for Outside Air/2 Openings.
The above requirements are for the water heater only; additional gas fired appliances in the equipment room will require an
increase in the net free area to supply adequate combustion air for all appliances.
**Combined interior space must be 50 cubic feet per 1,000 Btu/hr input. Buildings MUST NOT be of *“Tight Construction”.
For buildings of *“Tight Construction”, provide air openings into the building from outside.
*No combustion air openings are needed when the water heater is installed in a space with a volume NO LESS than 50 cubic feet
per 1,000 Btu/hr of all installed gas fired appliances. Buildings MUST NOT be of *“Tight Construction”.
*“Tight Construction” is defined as a building with less than 0.40 ACH (air changes per hour).