8
•
Ensure upflow or horizontal furnaces are not installed directly on carpeting, or any other combustible material. The
only combustible material allowed is wood.
•
A special accessory subbase must be used for upright counterflow unit installations over any combustible material
(including wood). Refer to subbase instructions for installation details. (
NOTE:
A subbase will not be required if an
air conditioning coil is located beneath the furnace between the supply air opening and the combustible floor.
•
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:
permanent wave solutions
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
• Isolate a non-direct furnace from an area contaminated by any of the above substances. This protects the
non-
direct vent
furnace from airborne contaminants. To ensure that the enclosed
non-direct
vent
furnace has an
adequate supply of combustion air, air must be ducted in from a nearby uncontaminated room or from outdoors.
Refer to the
Combustion and Ventilation Air Requirements
for details.
• If the furnace is used in connection with a cooling unit, install the furnace upstream or in parallel with the cooling
coil. Premature heat exchanger failure will result if the cooling coil is placed upstream of the furnace.
For vertical (upflow or downflow) applications, the minimum cooling coil width shall not be less than furnace width
minus 1”. Additionally, a coil installed above an upflow furnace or under a counterflow 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 upflow 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 floor. Protect the furnace from physical damage by vehicles.
• If the furnace is installed horizontally, ensure the access doors are not on the “up/top” or “down/bottom” side of
the furnace.
• Do not connect this furnace to a chimney flue that serves a separate appliance designed to burn solid fuel.
• On Counterflow Installations, the air conditioning coil must be downstream on the supply (positive) side of the
furnace heat exchanger.
•
Counterflow Installation over a noncombustible floor.
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
floor by using a silicone rubber caulking compound or cement grout.
•
Counterflow Installation over a combustible floor.
If installation over a combustible floor becomes necessary, use
an accessory subbase (see Specification Sheet applicable for your model for details.) A special accessory subbase
must be used for upright counterflow unit installations over any combustible material including wood. Refer to
subbase instructions for installation details. Follow the instructions with the subbase for proper installation. Do
not install the furnace directly on carpeting, tile, or other combustible material other than wood flooring. (
NOTE
:
The subbase will not be required if an air conditioning coil is installed between the supply air opening on the
furnace and the floor.)
C
LEARANCES
AND
A
CCESSIBILITY
NOTES:
•
For servicing or cleaning, a 24” front clearance is required.
•
Unit connections (electrical, flue and drain) may necessitate
greater clearances than the minimum clearances listed above.
•
In all cases, accessibility clearance must take precedence over
clearances from the enclosure where accessibility clearances are
greater.
POSITION*
FRONT
SIDES
REAR
TOP
FLUE
FLOOR
Upflow
3"
0"
0"
1"
0"
C
Horizontal
Alcove
6"
0"
4"
0"
C
C = If placed on combustible floor, floor MUST be wood only.
*MVM97* MINIMUM CLEARANCES TO COMBUSTIBLE MATERIALS
(INCHES)
