Weil-McLain Aqua Balance WMB-120, Manual, Page: 22 / 132

Part number 550-100-305/0118
22
AquaBalance TM
W
ALL
M
OUNT GAS
-
FIRED WATER BOILER
—
Boiler Manual
9 Boiler room air openings
Figure 24 Combustion and ventilation air openings for Direct Vent installations, also follow the National Fuel Gas Code,
ANSI Z223.1/NFPA 54 - latest edition, and/or Natural Gas and Propane Installation Code, CAN/CSA B149.1 or
applicable provisions of the local building codes.
The boiler CANNOT be in the same space with other appliances if clearances around the are less than the recom-
mended service clearances shown in Figure 2, page 7.
Air openings
The required air opening sizes below are FREE AREA,
after reduction for louver obstruction. Note the ex-
ception below for large spaces.
Boiler
WITH other
appliances in room
Boiler
WITHOUT other
appliances in room
TWO openings, each at least:
1 square inch per 1,000 Btuh
of all other appliances in the room
(Unless specified otherwise by
appliance manufacturer)
NO openings are required if the
boiler installation provides at least the
recommended service clearances
shown in Figure 2, page 7.
Provide openings ONLY as shown
in Figure 2, page 7
.
Each opening must have a free
area no less than 1 square inch per
1,000 Btuh input of the boiler.
TWO openings, each at least:
1
square inch per
4,000
Btuh
of all other appliances in the room
— OR —
ONE opening **, each at least:
1
square inch per
3,000
Btuh
of all other appliances in the room
(Unless specified otherwise by
appliance manufacturer)
TWO openings, each at least:
1 square inch per 4,000 Btuh
of all other appliances in the room
— OR —
ONE opening **, each at least:
1 square inch per 3,000 Btuh
of all other appliances in the room
(Unless specified otherwise by
appliance manufacturer)
TWO openings, each at least:
1 square inch per 2,000 Btuh
of all other appliances in the room
— OR —
ONE opening **, each at least:
1 square inch per 3,000 Btuh
of all other appliances in the room
(Unless specified otherwise by
appliance manufacturer)
** NOTICE:
Requirements for using the SINGLE air opening
option.
A single combustion air opening can be used for cases b, c or d above (boiler with
other appliances in room only), sized as listed, provided that:
• The single opening must communicate directly to the outdoors or to a space that
communicates directly with outdoors (NOT to an interior space).
• The top of the opening must be within 12 inches of the ceiling.
• The free area of the opening must be at least equal to the sum of the areas of all
equipment vent connectors in the space.
SPECIAL EXCEPTION FOR LARGE SPACES
(Boiler WITH other appliances in room only):
NO combustion air openings are needed if the boiler (and other appliances) are
installed in a space with a volume NO LESS than 50 cubic feet per 1,000 Btuh of all
appliances in the space. That is, total the input of all appliances in MBH (1,000’s of
Btuh), then multiply this total times 50. The building MUST NOT be of tight construction.
Example: For a total input of 500 MBH (500,000 Btuh), the minimum volume would
be 50 x 500 = 25,000 cubic feet.