A furnace installed in a confined space (for example, a closet or
utility room) must have 2 ventilation openings with a total
minimum free area of 0.25 sq. in. per 1,000 Btu/h of furnace input
rating. Refer to the Specification Sheet applicable to your model
for minimum clearances to combustible surfaces. One of the
ventilation openings must be within 12" (30.5 cm) of the top. The
other opening must be within 12" (30.5 cm) of the bottom of the
confined space. In a typical construction, the clearance between
the door and door frame is usually adequate to satisfy this
If suspending the furnace from rafters or joists, use ³⁄₈" threaded
rod and 2" x 2" x ¹⁄₈" (5.1 cm x 5.1 cm x 3.2 mm) angle iron as
shown in "Suspended Furnace" illustration. The length of rod will
depend on the application and the clearances necessary.
NOTE: In a horizontal installation, the air conditioning coil must
be adequately supported by the proper brackets and supports.
Inadequate coil support can result in furnace cabinet distortion
and air leakage.
A. ³⁄₈ " (1 cm) diameter threaded
B. 8" (20.3 cm) minimum clearance
between center rod and furnace
cabinet to allow for circulator
C. Level furnace end to end, slight
forward tilt with front 0" to ³⁄₄ "
(1.9 cm) below back.
Existing Furnace Removal
NOTE: When an existing furnace is removed from a venting
system serving other appliances, the venting system may be too
large to properly vent the remaining attached appliances.
D. Tilt outward to allow for door and
circulator blower removal.
E. Position as close as possible to
blower deck to allow for
circulator blower removal.
F. 2" x 2" x ¹⁄₈ " (5.1 cm x 5.1 cm x
3.2 mm) angle iron (3)
G. Support nuts
H. Hold down nuts
The following vent testing procedure is reproduced from the
American National Standard/National Standard of Canada for
Gas-Fired Central Furnaces ANSI Z21.4, CSA-2.3 latest edition
The following steps shall be followed with each appliance
connected to the venting system placed in operation, while any
other appliances connected to the venting system are not in
1. Seal any unused openings in the venting system.
2. Inspect the venting system for proper size and horizontal
pitch, as required by the National Fuel Gas Code, ANSI
Z223.1 or the Natural Gas and Propane Installation Code,
CSA B149.1-05 and these instructions. Determine that there
is no blockage or restriction, leakage, corrosion and other
deficiencies which could cause an unsafe condition.
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 shall operate at
maximum speed. Do not operate a summer exhaust fan.
6. Follow the lighting instructions. Place the appliance being
inspected in operation. Adjust thermostat so appliance shall
7. Test for leaking from draft hood appliances at the draft hood
relief opening after 5 minutes of main burner operation. Use
the flame of a match or candle.
8. 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 burning appliance to their
previous conditions of use.
9. 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
National Gas and Propane Installation Code CSA B149.1-05.
If resizing is required on any portion of the venting system, use
the appropriate table in Appendix G in the latest edition of the
National Fuel Gas Code ANSI Z223.1 and/or CSA B149.1-05
The thermostat should be placed approximately 5 ft (1.5 m) from
the floor on a vibration-free, inside wall in an area having good air
NOTE: Do not install the thermostat where it may be influenced
by any of the following:
Drafts, or dead spots behind doors, in corners or under
Hot or cold air from registers
Radiant heat from the sun
Light fixtures or other appliances
Radiant heat from a fireplace
Concealed hot or cold water pipes or chimneys
Unconditioned areas behind the thermostat, such as an
Consult the instructions packaged with the thermostat for
mounting instructions and further precautions.