Install Instructions (Venting)

Part number 550-100-103/1110
A–21
GAS-FIRED WATER BOILER — Manual addendum — Venting
DIRECT EXHAUST — Boiler room air openings (continued)
MINIMUM combustion air openings for direct exhaust applications — Figure 24 ALL OPENING SIZES ARE FREE AREA
Air openings
The required air opening sizes below are FREE AREA,
after reduction for louver obstruction. Note the ex-
ception below for large spaces.
Ultra boiler
WITH other
appliances in room
Ultra boiler
WITHOUT other
appliances in room
TWO openings, each at least:
1 square inch per 1,000 Btuh
of all appliances in the room
TWO openings, each at least:
1 square inch per 4,000 Btuh
of all appliances in the room
TWO openings, each at least:
1 square inch per 4,000 Btuh
of all appliances in the room
— OR —
ONE opening **, each at least:
1 square inch per 3,000 Btuh
of all appliances in the room
TWO openings, each at least:
1 square inch per 4,000 Btuh
of all appliances in the room
— OR —
ONE opening **, each at least:
1 square inch per 3,000 Btuh
of all appliances in the room
TWO openings, each at least:
1 square inch per 2,000 Btuh
of all appliances in the room
— OR —
ONE opening **, each at least:
1 square inch per 3,000 Btuh
of all appliances in the room
TWO openings, each at least:
1 square inch per 4,000 Btuh
of all appliances in the room
— OR —
ONE opening **, each at least:
1 square inch per 3,000 Btuh
of all appliances in the room
TWO openings, each at least:
1 square inch per 4,000 Btuh
of all appliances in the room
— OR —
ONE opening **, each at least:
1 square inch per 3,000 Btuh
of all appliances in the room
TWO openings, each at least:
1 square inch per 4,000 Btuh
of all appliances in the room
— OR —
ONE opening **, each at least:
1 square inch per 3,000 Btuh
of all appliances in the room
** NOTICE:
Requirements for using the SINGLE air open-
ing option.
A single combustion air opening can be used for cases b, c or d above, sized as listed,
provided that:
The single opening must communicate directly to the outdoors or to a space that s
communicates directly with outdoors (NOT to an interior space).
The top of the opening must be within 12 inches of the ceiling.s
The free area of the opening must be at least equal to the sum of the areas of all s
equipment vent connectors in the space.
SPECIAL EXCEPTION FOR LARGE SPACES:
NO combustion air openings are needed when 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 1500 MBH (1,500,000 Btuh) and an 8-foot ceiling height,
the minimum volume would be 50 x 1500 x 8 = 60,000 cubic feet.