Existing Venting Systems
When an existing furnace is removed or replaced, the original
venting system may no longer be sized to properly vent the
attached appliances. An improperly sized venting system can
result in spillage of flue products into the living space, the
formation of condensate, leakage, etc. See the "Carbon
Monoxide Poisoning Hazard" for proper test procedure.
CARBON MONOXIDE POISONING HAZARD
Failure to follow the steps outlined below for each
appliance connected to the venting system being
placed into operation could result in carbon monoxide
poisoning or death.
The following steps shall be followed for each appliance
connected to the venting system being placed into operation,
while all other appliances connected to the venting system are
not in operation:
1. Seal any unused openings in the venting system.
2. Inspect the venting system for proper size and horizontal
pitch, as required in the National Fuel Gas Code,
ANSI Z223.1/NFPA 54 or the CSA B149.1, Natural Gas and
Propane Installation Codes and these instructions.
Determine that there is no blockage or restriction, leakage,
corrosion and other deficiencies which could cause an
3. As far as practical, close all building doors and windows
and all doors between the space in which the appliance(s)
connected to the venting system are located and other
spaces of the building.
4. Close fireplace dampers.
5. Turn on clothes dryers and any appliance not connected to
the venting system. Turn on any exhaust fans, such as
range hoods and bathroom exhausts, so they are operating
at maximum speed. Do not operate a summer exhaust fan.
6. Follow the lighting instructions. Place the appliance being
inspected into operation. Adjust the thermostat so
appliance is operating continuously.
7. Test for spillage from draft hood equipped appliances at the
draft hood relief opening after 5 minutes of main burner
operation. Use the flame of a match or candle.
8. If improper venting is observed during any of the above
tests, the venting system must be corrected in accordance
with the National Fuel Gas Code, ANSI Z223.1/NFPA 54
and/or CSA B149.1, Natural Gas and Propane Installation
9. After it has been determined that each appliance connected
to the venting system properly vents when tested as
outlined above, return doors, windows, exhaust fans,
fireplace dampers and any other gas-fired burning
appliances to their previous conditions of use.
The furnace can be installed as either direct vent or nondirect
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" (1.3 cm)
insulation must be used over the pipe. In extremely cold
climates, ³⁄₄" (1.9 cm) insulation is recommended.
A nondirect 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 (nondirect
vent), attach a 90° elbow (not supplied) to the inlet coupler
and install the restrictor plate inside the elbow (see
"Nondirect Vent Installation").
Inlet Air Restrictor Plate
A 2" (5.1 cm) restrictor plate is supplied with the 40, 60, 80
and 100k Btu/h models. A 3" (7.6 cm) restrictor plate is
supplied with the 125k Btu/h model.
In horizontal applications, the restrictor plate must be
secured to the inlet collar by inserting a field supplied piece of
2" (5.1 cm) or 3" (7.6 cm) PVC pipe into the inlet collar after
the restrictor plate is installed. Use high temperature RTV
sealant to attach the PVC to the inlet collar.
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