# 47904K005
Page 4
Unconfined Space
An unconfined space is defined as “a space whose
volume is more than 50 cubic feet per 1000 BTU per hour
of the combined input rating of all appliances installed in
that space.” When a furnace is installed in an unconfined
space in a building, it can be assumed that the infiltration
will be sufficient to supply the required air. If the furnace is
installed in a ventilated attic or crawl space, it is assumed
that the infiltration is sufficient to supply the required air.
However, in a building of unusually tight construction,
additional outdoor air should be provided.
•
Air filters must be installed in the system and must be
maintained during construction.
•
Air filters must be replaced upon construction comple-
tion.
•
The input rate and temperature rise must be set per
the furnace rating plate.
•
One hundred percent (100%) outdoor air must be
provided for combustion air requirements during
construction. Temporary ducting may supply outdoor
air to the furnace. Do not connect duct directly to the
furnace. Size the temporary duct following the instruc-
tions given on page 5 in the
Combustion and
Ventilation Air
section regarding confined space with
air from outside.
•
The furnace heat exchanger, components, duct
system, air filters, and evaporator coils must be
thoroughly cleaned following final construction
cleanup.
•
All furnace operating conditions (including ignition,
input rate, temperature rise, and venting) must be
verified according to these installation instructions.
G2D93CT and G2D95CT models installed in the horizon-
tal position are approved for attic installations.
If the
furnace is to be installed in an attic or other insulated
space, it must be kept free and clear of insulating
materials.
To avoid property damage caused by condensate drain
blockage, install a field-fabricated auxiliary drain pan with
a separate drain line to the outside under the entire
furnace and drain system. Install according to local codes.
Clearances
All servicing and cleaning of the furnace can be performed
from the front. If installed in a closet or utility room,
provide 18" clearance in front for service if the door to the
room is not in line with the front of the furnace.
Refer to Table 1 for the minimum clearances to combus-
tibles required for construction and proper unit operation.
Where servicing clearances are greater than clearances
to combustibles, servicing clearances take precedence.
G2D93CT and G2D95CT models may be installed on wood
flooring but shall not be installed directly on carpeting, tile, or
any other combustible material.
Combustion and Ventilation Air
Adequate provisions for combustion air and ventilation of
furnace must be made. Refer to Section 5.3, “Air for
Combustion and Ventilation,” of the National Fuel Gas
Insufficient combustion air can cause head-
aches, nausea, dizziness, or asphyxiation.
When considering combustion air require-
ments, enough air must also be provided to
meet the needs of all fuel-burning appliances
and exhaust fans.
WARNING
Air openings in the front of the furnace must
be kept free of obstructions. Any obstruction
may cause improper operation that can result
in a fire hazard or carbon monoxide injury.
WARNING
Code, ANSI Z223.1/NFPA54 (latest edition), Sections 7.2,
7.3, or 7.4 of CSA B149.1 Natural Gas and Propane
Installation Codes (latest editions), or applicable provi-
sions of the local building codes.
Table 1
Minimum Clearances to
Combustibles
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