Installation Guide

6
Do not install the furnace directly on carpeting, tile, or
other combustible material other than wood fl ooring.
(NOTE: The subbase will not be required if an air
conditioning coil is installed between the supply
air opening on the furnace and the fl oor. The air
conditioning coil must be downstream from the heat
exchanger of the furnace.
Top - 1"
Side
Clearance - 1"
Back - 0"
Front Clearance - 3"
Vent Pipe Clearance to Combustibles-
6" using Single Wall Connector or 1"
using B-1 vent.
Figure 1
• Adequate combustion/ventilation air must be supplied
to the closet.
• Furnace must be completely sealed to floor or
base. Combustion/ ventilation air supply pipes must
terminate 12” from top of closet and 12” from fl oor
of closet. DO NOT remove solid base plate for side
return.
• Return air ducts must be completely sealed to
the furnace and terminate outside the enclosure
surfaces.
CLEARANCES AND ACCESSIBILITY
Unobstructed front clearance of 24” for servicing is recom-
mended.
TOP
B1-VENT SINGLE
(PLENUM)
1" 6" 1" 3" 0" 1"
VENT
SIDES
FRONT
BACK
Top clearance for horizontal confi guration - 1”
INSTALLATION POSITIONS
*MEC80 model furnaces may be installed vertically (upfl ow) or
horizontally with left or right side down. *CEC80 model furnac-
es may be installed vertically (downfl ow) or horizontally with
left or right side down. Do not install this furnace on its back.
For vertically installed upfl ow furnaces, return air ductwork
may be attached to the side panel(s) and/or basepan. For
horizontally installed upfl ow furnaces, return air ductwork must
be attached to the basepan. For counterfl ow furnaces, return
ductwork must be attached to the the blower compartment
end of the furnace.
NOTE: Ductwork must never be attached to the back of the
furnace.
• Exposure to contaminated combustion air will result
in safety and performance-related problems. Do
not install the furnace where the combustion air is
exposed to the following substances:
chlorinated waxes or cleaners
chlorine-based swimming pool chemicals
water softening chemicals
deicing salts or chemicals
carbon tetrachloride
halogen type refrigerants
cleaning solutions (such as perchloroethylene)
printing inks
paint removers
varnishes
hydrochloric acid
cements and glues
antistatic fabric softeners for clothes dryers
and masonry acid washing materials
• If the furnace is used in connection with a cooling
unit, install the furnace upstream or in parallel with the
cooling unit coil. Premature heat exchanger failure
will result if the cooling unit coil is placed ahead of
the furnace.
• For vertical applications, the minimum cooling coil
width shall not be less than furnace width minus 1”.
Additionally, a coil installed above an upfl ow furnace
or under a counterfl ow furnace may be the same width
as the furnace or may be one size larger than the
furnace. Example: a “C” width coil may be installed
with a “B” width furnace.
• For upfl ow applications, the front of the coil and
furnace must face the same direction.
• If the furnace is installed in a residential garage,
position the furnace so that the burners and ignition
source are located not less than 18 inches (457 mm)
above the fl oor. Protect the furnace from physical
damage by vehicles.
• If the furnace is installed horizontally, the furnace
access doors must be vertical so that the burners fi re
horizontally into the heat exchanger. Do not install the
unit with the access doors on the “up/top” or “down/
bottom” side of the furnace.
• Do not connect this furnace to a chimney fl ue that
serves a separate appliance designed to burn solid
fuel.
• Counterfl ow installation over a noncombustible fl oor.
Before setting the furnace over the plenum opening,
ensure the surface around the opening is smooth
and level. A tight seal should be made between the
furnace base and fl oor by using a silicon rubber
caulking compound or cement grout.
• Counterfl ow installation over a combustible fl oor.
If installation over a combustible floor becomes
necessary, use an accessory subbase (see
Specifi cation Sheet applicable to your model for
details). A special accessory subbase must be used
for upright counterfl ow unit installations over any
combustible material including wood. Follow the
instructions with the subbase for proper installations.