Do not place combustible material on furnace jacket. Failure
to comply with this warning will create a fire hazard.
This furnace is not watertight and is not designed for outdoor
installation. This furnace shall be installed in such a manner
as to protect the electrical components from water. Outdoor
installation would lead to a hazardous electrical condition and
premature component failure.
AIR FOR COMBUSTION AND VENTILATION
Step 1—General
Provisions for adequate combustion and ventilation air must be
provided in accordance with Section 5.3, Air for Combustion and
Ventilation, of the NFGC, ANSI Z223.1-1992, or applicable
provisions of local building codes.
Canadian installations must be installed in accordance with the
NSCNGPIC and all authorities having jurisdiction.
Do not block combustion air openings in furnace. Any
blockage will result in improper combustion and may result in
a fire hazard or unsafe condition.
Air for combustion must not be contaminated by halogen
compounds which include fluoride, chloride, bromide, and
iodide. These elements are found in aerosol sprays, deter-
gents, bleaches, cleaning solvents, salts, air fresheners, and
other household products.
Excessive exposure to contaminated combustion air will
result in safety and performance related problems.
The operation of exhaust fans, kitchen ventilation fans,
clothes dryers, or fireplaces could create a negative pressure
condition at the furnace. Make-up air must be provided for the
ventilation devices, in addition to that required by the furnace.
All fuel-burning equipment must be supplied with air for combus-
tion of the fuel. Sufficient air MUST be provided to ensure there
will not be a negative pressure in the equipment room or space. In
addition, a positive seal MUST be made between furnace cabinet
and return-air duct to avoid pulling air from burner area and draft
safeguard opening.
The furnace shall be installed in a location in which the facilities
for ventilation permit satisfactory combustion of gas, proper
venting, and maintenance of ambient temperature at safe limits
under normal conditions of use. The furnace shall be located so as
not to interfere with proper circulation of air.
In addition to air needed for combustion, process air must be
provided as required for cooling of equipment or material, con-
trolling dew point, heating, drying, oxidation or dilution, safety
exhaust, and odor control. Air must be supplied for ventilation,
including all air required for comfort and proper working condi-
tions for personnel.
Whenever this furnace is installed in an area along with 1 or
more gas appliances, the total Btuh input of all appliances
must be included when determining the free area require-
ments for combustion and ventilation openings.
The requirements for combustion and ventilation air depend upon
whether the furnace is located in a confined or unconfined space.
Step 2—Unconfined Space
An unconfined space must have at least 50 cu ft for each 1000
Btuh of input for all appliances such as furnaces, clothes dryer,
water heaters, etc. in that space. Rooms communicating with the
space in which the appliances are installed through openings not
furnished with doors are considered a part of the unconfined space.
If the unconfined space is of unusually tight construction, air for
combustion and ventilation MUST come from either the outdoors
or spaces freely communicating with the outdoors. Combustion
and ventilation openings must be sized the same as for a confined
space. A minimum opening with a total of at least 1 sq in. per 5000
Btuh of total input rating for all equipment must be provided.
Return air must not be taken from the room unless an equal or
greater amount of air is supplied to the room.
Step 3—Confined Space
A confined space has less than 50 cu ft for each 1000 Btuh of the
total input ratings of all appliances installed in that space.
A confined space MUST have 2 permanent openings, 1 within 12
in. of the ceiling and the other within 12 in. of the floor.
NOTE:
In determining the free area of an opening, the blocking
effect of the louvers, grilles, and screens must be considered. If the
free area of a louver or grille design is unknown, assume that wood
louvers have a 20 percent free area and metal louvers or grilles
have a 60 percent free area. Screens, when used, must not be
smaller than 1/4-in. mesh. Louvers and grilles must be constructed
so they cannot be closed.
The size of the openings depends upon whether the air comes from
inside or outside of the structure.
ALL AIR FROM INSIDE THE STRUCTURE:
1. Each opening MUST have at least 1 sq in. of free area per
1000 Btuh of the total input for all equipment within the
confined space, but not less than 100 sq in. per opening.
2. If the building is of unusually tight construction, a permanent
opening directly communicating with the outdoors should be
provided. This opening should have a minimum free area of 1
sq in. per 5000 Btuh of total input rating for all equipment in
the enclosure.
3. If the furnace is installed on a raised platform to provide a
return-air plenum, and return air is taken directly from the
hallway or space adjacent to the furnace, all air for combustion
must come from outdoors.
For Example:
58EFB FURNACE
INPUT BTUH
FREE AREA PER
OPENING (SQ IN.)
50,000
100
75,000
100
100,000
100
125,000
125
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