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Duct Work Installation
We strongly recommend that the hot air ductwork
be installed by a home heating specialist. If doing
the installation yourself, before you decide which
installation will best suit your needs, consult a qualified
heating technician and follow his recommendations
as to the safest and most efficient method of
installation.
This furnace can be installed in two ways, as a stand
alone or parallel unit, with an existing furnace.
SUPPLY AIR (HOT AIR) PLENUM
The warm-air supply duct shall be constructed
of metal in accordance with NFPA 90B, 2-1.1. The
plenums installed to the furnace shall be constructed
of metal in accordance with NFPA 90B, 2-1.3.
When installing this furnace the hot air plenum is to
have a minimum height of 24” (610mm) if the top
of the first vertical section is not flush with the top of
the first horizontal section of ductwork. If the top of
the plenum is flush with the top of the first horizontal
section of ductwork then the minium height is 15”
(381mm).
RETURN AIR (FRESH AIR)
The return (fresh) air intake on the furnace is on the
rear of the unit. The ductwork must be mechanically
attached to the unit or UFB908 blower box with sheet
metal screws to ensure a proper operation.
STAND ALONE INSTALLATION
If installing this furnace as a stand alone unit, ensure
all local codes and all instructions in this manual are
followed, including clearance to combustibles, floor
protector specifications and safety warnings.
21”
6”
Supply Air (Hot Air) Duct Work Outlet Size
Supply Air Plenum Minimum
Height Of 24”
Supply Air Plenum With
Minimum Height Of 15”
CENTRAL INSTALLATION
-6-
MAINTENANCE CLEARANCES
Your furnace has recommended minimum maintenance clearance requirements. These clearances insure that
there is adequate room to preform maintenance and service your furnace. DO NOT store fuel within the specified
clearances. See the table and diagram below to determine the clearances for your furnace.
Dimension
Inch
mm
K
Maintenance Clearance (Front) 24
610
L
Maintenance Clearance (Left)
24
610
M
Maintenance Clearance (Right) 24
610
N
Maintenance Clearance (Rear)
36
915
Q
O
R
P
S
S
M
L
N
K
MAINTENANCE CLEARANCE
FLOOR PROTECTOR REQUIREMENTS
FLOOR PROTECTOR
The furnace must be placed on solid concrete, solid masonry, or when installed on a combustible floor, on a floor
protector. The floor protector is required to provide heat, live ember, and ash protection and must be of a non-
combustible, continuous solid surface to protect against infiltration of live embers and ash. Floor protection must
have and R-Value of at least 1.4. Refer to floor protector manufacturer’s instructions for installation directions.
The floor protector or non combustible floor must extend under the furnace and beyond each side as shown
below.
Dimension
Inch
mm
O*
Front
16
407
P
Flue rear
2
51
Q**
Left
8
204
R**
Right
8
204
S
Flue Side
2
51
