SYSTEM OPERATION
9
•
Locate the furnace so condensate flows downwards to
the drain. Do not locate the furnace or its condensate
drainage system in any area subject to below freezing
temperatures without proper freeze protection. Refer
to
Condensate Drain Lines and Trap
for further details.
•
Ensure adequate combustion air is available for the
furnace. Improper or insufficient combustion air can
expose building occupants to gas combustion products
that could include carbon monoxide. Refer to
Combus-
tion and Ventilation Air Requirements.
•
Set the furnace on a level floor to enable proper con
-
densate drainage. If the floor becomes wet or damp at
times, place the furnace above the floor on a concrete
base sized approximately 1-1/2" larger than the base
of the furnace. Refer to the
Horizontal Applications and
Considerations
for leveling of horizontal furnaces.
•
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
cleaning solutions (such as perchloroethylene)
printing inks
chlorinated waxes or cleaners
paint removers
chlorine-based swimming pool chemicals
varnishes
water softening chemicals
hydrochloric acid
carbon tetrachloride
cements and glues
deicing salts or chemicals
halogen type refrigerants
antistatic fabric softeners for clothes dryers
and masonry acid washing materials
•
Isolate a
non-direct vent
furnace if it is installed near
an area frequently contaminated by any of the above
substances. This protects the
non-direct vent
furnace
from airborne contaminants. To ensure that the en
-
closed
non-direct
vent
furnace has an adequate supply
of combustion air, vent 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 coil
unit, install the furnace upstream or in parallel with the
cooling coil unit. Premature heat exchanger failure will
result if the cooling unit is placed ahead of the furnace.
For vertical (upflow or downflow) applications, the min
-
imum 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 appli
-
cations, the front of the coil and furnace must face the
same direction.
•
If the furnace is installed in a residential garage, posi
-
tion 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.
•
C
ounterflow 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 com
-
pound or cement grout.
•
Counterflow Installation over a combustible floor.
If
installation over a combustible floor becomes neces
-
sary, 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 includ
-
ing 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.)
POSITION*
SIDES
REAR
FRONT BOTTOM
FLUE
TOP
Upflow
0"
0"
3"
C
0"
1"
Horizontal
6"
0"
3"
C
0"
6"
C = If placed on combustible floor, floor MUST be wood only.
*MVM97 MINIMUM CLEARANCES TO COMBUSTIBLE MATERIALS
(INCHES)
