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Table 3
Downflow Installation Clearances
Clearances
Bottom of Plenum and Ductwork
Plenum Sides
Side of Cabinet
Rear of Cabinet
Front of Cabinet
Service Clearance (Front)
Flue Pipe Horizontal
Flue Pipe Vertical
Return Air Opening
*Floor
*NOTE-Clearance for installation on combustible floor if
optional additive base is installed between the furnace
and combustible floor. Not required in add-on coiling ap
plications.
NOTE - Downflow Application Only - For installation on
combustible floors, appliance shall not be installed directly
on carpeting, tile or other combustible material other than
wood flooring. When installed on wood flooring, the addi
tive base must be used. See Unit Dimension illustration.
NOTE - Unit must be adjusted to obtain a temperature rise
within the range listed in table 8.
When used in conjunction with a evaporator coil, the fur
nace shall be installed in parallel with, or on the upstream
side of the evaporator coil. In a parallel flow arrangement,
the dampers, or other measures used to control flow of air
flow, shall be adequate to prevent chilled air from entering
the furnace. If the furnace is manually operated, it must be
equipped with means to prevent operation of either unit un
less dampers are in the full‐heat or full‐cool position.
When installed, furnace must be electrically grounded in
accordance with local codes or, in the absence of local
codes, with the current National Electric Code, ANSI/
NFPA No. 70, if an external electrical source is utilized.
Field wiring connection with unit must meet or exceed
specifications of type T wire and withstand a 63_F (17_C)
temperature rise.
Notice to Home Owner
This furnace is equipped with safety devices that protect
you and your property. If one or more of these devices is
activated, furnace operation will stop. If your home is left
unattended for an extended period of time, equipment op
eration must be checked periodically. If this is not possible,
the water supply to the house should be shut off and the
pipes should be drained. This will prevent problems
associated with a NO HEAT condition (frozen pipes, etc.)
Homes built with energy conservation in mind use tight
construction practices. These houses are sealed so well
Inches (mm)
that it becomes necessary to provide a means of bringing
1 (25)
in air from outside for combustion. Also, exhaust fans, ap
1 (25)
pliance vents, chimneys and fireplaces force additional air
that could be used for combustion out of the house. Unless
1 (25)
outside air is brought into the home for combustion, nega
1 (25)
tive pressure (pressure outside is greater than inside pres
16 (406)
sure) will build to the point that a down draft can occur in the
24 (610)
furnace vent pipe or chimney. Combustion gases enter the
1 (25)
living space creating a potentially dangerous situation. Ne
gative pressure may also interfere with proper combus
7 (178)
tion, causing sooting within the heat exchanger.
0 (0)
The importance of the previous paragraph cannot be over
*Combustible
stated. Users may inadvertently block fresh air intakes af
ter installation.
In the absence of local codes concerning air for combus
tion and ventilation, the following section outlines guide
lines and recommends procedures for operating oil fur
naces in a manner that ensures efficient and safe
operation. Special consideration must be given to com
bustion air needs as well as requirements for exhaust
vents and oil piping.
Combustion Air Requirements
All oil‐fired appliances require air to be used for the com
bustion process. If sufficient amounts of combustion air
are not available, the furnace or other appliance will oper
ate in an inefficient and unsafe manner. Enough air must
be provided to meet the needs of all fuel‐burning ap
pliances, as well as appliances such as exhaust fans which
force air out of the home. When fireplaces, exhaust fans,
or clothes dryers are used at the same time as the furnace,
much more air is required to ensure proper combustion
and to prevent a down‐draft situation. Insufficient amounts
of air also cause incomplete combustion which can result
in sooting. Requirements for providing air for combustion
and ventilation depend largely on whether the furnace is
installed in an unconfined or confined space.
Unconfined Space
An unconfined space is an area such as a basement or
large equipment room with a volume greater than 50 cubic
feet (1.4 cubic meters) per 1,000 Btu (293 W) per hour of
the combined input rating of all appliances installed in that
space. This space also includes adjacent rooms which are
not separated by a door. Though an area may appear to be
unconfined, it might be necessary to bring in outdoor air for
combustion if the structure does not provide enough air by
Page 5
Combustion & Ventilation Air
CAUTION
Insufficient combustion air can cause headaches,
nausea, dizziness or asphyxiation. It will also cause
excess water in the heat exchanger resulting in rust
ing and premature heat exchanger failure. It can also
cause property damage.
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