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Part number 550-142-054/0411
GV90+ gas-fired water boiler — Boiler Manual
50
DIRECT EXHAUST —
Boiler room air openings
(cont.)
Figure 60 MINIMUM combustion air openings for direct exhaust applications — ALL OPENING SIZES ARE FREE AREA
The GV90+ boiler CANNOT be in the same space with other appliances if
clearances around the GV90+ are less than the recommended service clearances
shown in Figure 2, page 6.
If the space is smaller than
Figure 2, page 6, provide
openings ONLY as shown on
page 7 and Figure 4, page 7.
GV90+ boiler
WITHOUT other
appliances in room
Air openings
The required air opening sizes below are FREE AREA,
after reduction for louver obstruction. Note the ex-
ception below for large spaces.
GV90+ boiler
WITH 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 opening
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
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:
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 ap-
pliances 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 (3,125 square feet if ceiling height is 8 feet).