W:\ELECTRICAL\INSTRUCT\FURNACE\FURNACE GENERAL INSTRUCTIONS 2011.DOC
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3-2.4
Level the furnace using shims, if necessary. Where mounting holes are provided,
anchor the furnace securely. Shims should be permanently mounted to the furnace
after installation.
3-3 CLEARANCES
3-3.1
Furnaces shall be located with adequate space above and on all sides to allow for
inspection, maintenance and operator access. Provisions also shall be included for
unobstructed discharge of building sprinklers, the installation of automatic fire
protection system within the furnace, if necessary and the proper functioning of
explosion relief doors and panels.
3-3.2
Do not place the furnace up against a wall. A minimum air space of 12 inches must
be provided on all sides to allow for air circulation, with additional space being
provided for furnaces operating over 1400°F (760°C) to keep temperature at
adjacent structures and materials below 160°F (70°C). Local, city and state codes
may specify building requirements and special provisions for locating furnaces.
3-3.3
The furnace should be located so there is unrestricted air circulation around all
motors for proper cooling.
3-3.4
Do not store material on top of furnace. The furnace is not designed to support
external loads and material may get hot, ignite and cause a fire.
3-3.5
To prevent ignition of combustible material, combustible material shall be located at
a safe distance from furnace and furnace ductwork. The National Fire Protection
Association (NFPA) Standard 86 specifies a minimum distance of 2-1/2 feet;
Factory Mutual (FM) specifies at least 10 feet.
3-3.6
The furnace door travel must not be restricted and should face away from main
aisles, work areas and automatic sprinkler risers, feeds and cross mains.
3-4 VENTILATION
3-4.1
Where furnaces are located in basements or enclosed areas, sufficient room
ventilation shall be supplied to provide required combustion air for fuel fired
equipment and to prevent the hazardous accumulation of vapors from processing.
3-4.2
Furnaces designed for use with fuel gas or process gas having a specific gravity
greater than air (such as propane) shall be located at or above grade and shall be
located to prevent the escape of the fuel gas from accumulating in basements, pits,
or other areas below the furnace.
3-4.3
Fresh air inlets and exhaust outlets (if applicable) must never be restricted. If
filtered air is provided, there must be adequate filter capacity to prevent any
reduction in airflow even under adverse loading of the filter. The filters must be
periodically inspected and replaced as required.
3-4.4
A sufficient quantity of building make-up air should be admitted to furnace rooms
and buildings to provide the air volume required for furnace safety ventilation and
adequate combustion air for fuel fired equipment. Buildings should not operate
under a negative pressure.
