Page 4
Requirements
WARNING
Product contains fiberglass wool.
Disturbing the insulation in this product during
installation, maintenance, or repair will expose you
to fiberglass wool dust. Breathing this may cause
lung cancer. (Fiberglass wool is known to the State
of California to cause cancer.)
Fiberglass wool may also cause respiratory, skin,
and eye irritation.
To reduce exposure to this substance or for further
information, consult material safety data sheets
available from address shown below, or contact your
supervisor.
Lennox Industries Inc.
P.O. Box 799900
Dallas, TX 75379−9900
Installation of Lennox oil−fired furnaces must conform with
the National Fire Protection Association Standard for the
Installation of Oil Burning Equipment, NFPA No. 31, the
National Electrical Code, ANSI/NFPA No.70 (in the
U.S.A.), CSA Standard CAN/CSA−B139 (in Canada),
Installation Code for Oil Burning Equipment, the Canadian
Electrical Code Part1, CSA 22.1 (Canada), the recommen-
dations of the National Environmental Systems Contrac-
tors Association and any state or provincial laws or local or-
dinances. Authorities having jurisdiction should be
consulted before installation. Such applicable regulations
or requirements take precedence over general instructions
in this manual.
Chimneys and chimney connectors must be of the type and
construction outlined in section 160 of NFPA No. 31.
Air for combustion and ventilation must conform to stan-
dards outlined in section 140 of NFPA No. 31 or, in Canada,
CSA Standard B139. When installing OHR23 units in con-
fined spaces such as utility rooms, two combustion air
openings are required. Dimensions of combustion air
openings are shown in table 1. One opening shall be below
burner level and the other opening shall be no more than 6
inches from the room’s ceiling.
The combustion air opening should provide a minimum
free area one-half square inch per 1,000 Btu per hour input.
This combustion air should be brought into the area con-
taining the furnace below the level of the furnace burner.
IMPORTANT
An opening to the outside for combustion air is
strongly recommended, especially in new homes.
Refer to table 1 or the unit rating plate for specific
combustion air opening dimensions.
Table 1
Combustion Air Opening Dimensions
Model No.
Combustion Air Opening
Dimensions (2 required)
OHR23−105/120
10" X 20"
OHR23−140/154
11" X 22"
This unit is approved for clearances to combustible materi-
al as listed unit rating plate and in tables 2 or 3. Unit service
and accessibility clearances take precedence over fire
protection clearances.
Table 2
Horizontal Installation Clearances
Clearances
inches (mm)
Top of Cabinet
3 (76)
*Bottom and Rear of Cab-
inet
1 (25)
Front of Cabinet
24 (610)
Service Clearance (Front)
24 (610)
End of Supply Plenum
0 (0)
Supply Air Opening
0 (0)
Return Air Opening
0 (0)
Above Horizontal Warm
Air Duct
within 3 ft. (914mm) of
Furnace
0 (0)
Flue Pipe Horizontal
7 (178)
Flue Pipe Vertical
7 (178)
*NOTE When furnace is installed on combustible floor, 1 " (25 mm) spacer legs
must be installed to elevate unit off of mounting surface.
Table 3
Downflow Installation Clearances
CLEARANCES
INCHES (MM)
Bottom of Plenum and
Ductwork
1 (25)
Plenum Sides
1 (25)
Side of Cabinet
1 (25)
Rear of Cabinet
1 (25)
Front of Cabinet
16 (406)
Service Clearance (Front)
24 (610)
Flue Pipe Horizontal
1 (25)
Flue Pipe Vertical
7 (178)
Return Air Opening
0 (0)
*Floor
*Combustible
*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 applications.
NOTE Downflow Application Only For installation on
combustible floors, appliance shall not be installed directly
