Plan Vent System
The high efficiency of this furnace is accomplished by the
removal of both sensible and latent heat from the flue gases. The
removal of latent heat results in the condensation of moisture in
the flue gases. This condensation occurs in the secondary heat
exchanger and in the vent system. Therefore, this furnace
requires special venting considerations and the instructions must
be followed to ensure proper operation. All venting must be in
accordance with the codes having jurisdiction in the area and
The venting system must be supported with mounting straps
to prevent any weight load from being applied to the vent
blower. Horizontal vent pipe must be supported every 5 ft and
vertical pipe should be supported every 10 ft to prevent
sagging and provide rigid support.
This furnace must not be connected to any Type B, BW, or L
vent or vent connector and must not be connected to any
portion of a factory-built or masonry chimney.
This furnace is not to be common vented with any other
appliance. The vent pipe must not be connected to a
chimney flue serving a separate appliance designed to burn
WFCU, WFCC, WGFDC and WGFDU models can be installed as
either direct vent or non-direct vent units.
For either type of installation, special venting considerations
must be followed. See "Determine Vent Pipe Direction" section
for the type of furnace and venting being installed.
A direct vent (two pipe) installation requires that all the air
necessary for combustion be supplied from outside the dwelling
through an air intake pipe.
All vents passing through floors, ceilings, and walls must be
installed in accordance with National Fuel Gas Code, ANSI
Z223.1/NFPA 54 (latest edition). In all applications where the
flue pipe is run through an unconditioned space, ¹⁄₂ in.
insulation must be used over the pipe. In extremely cold
climates, ³⁄₄ in. insulation is recommended.
A non-direct vent (one pipe) installation uses air from inside the
dwelling for combustion.
The furnace is shipped with the air inlet pipe terminated to the
top panel for either inside or outside combustion air. An inlet
air restrictor plate is supplied with this furnace and can be
found in the plastic bag containing these Installation
Instructions and the User's Information Manual.
For installations using inside air for combustion (non-direct
vent), attach a 90° elbow (not supplied) to the inlet coupler
and install the restrictor plate inside the elbow (see "Non-
Direct Vent Installation").
Inlet Air Restrictor Plate
The inlet air restrictor plate
must be installed in all
installations using inside air
for combustion (non-direct
Flue Pipe Screen
A flue pipe screen designed to keep objects out of the flue pipe is
included in the plastic bag.
In all installations, this screen should be installed at the
termination of the flue pipe.
Flue Pipe Screen
The flue pipe screen
should be installed at the
termination of the flue pipe
in all installations.