When a furnace is installed so that supply ducts carry air circulated
by the furnace to areas outside the space containing the furnace,
return air must also be handled by ducts sealed to furnace casing.
The ducts terminate outside the space containing the furnace to
ensure there will not be a negative pressure condition within
equipment room or space.
WARNING: FIRE, INJURY, OR DEATH HAZARD
Failure to follow this warning could result in fire,
property damage, personal injury, or death.
Do not install furnace on its back. Safety control opera-
tion will be adversely affected. Never connect return-air
ducts to back of furnace. (See Fig. 14.)
CAUTION: UNIT DAMAGE HAZARD
This gas furnace may be used for construction heat provided that:
-The furnace is permanently installed with all electrical wiring, piping, air filters, venting and ducting installed according to these
installation instructions. A return air duct is provided, sealed to the furnace casing, and terminated outside the space containing the
furnace. This prevents a negative pressure condition as created by the circulating air blower, causing a flame rollout and/or drawing
combustion products into the structure.
-The furnace is controlled by a thermostat. It may not be ″hot wired″ to provide heat continuously to the structure without thermostatic
control.
-Clean outside air is provided for combustion. This is to minimize the corrosive effects of adhesives, sealers and other construction
materials. It also prevents the entrainment of drywall dust into combustion air, which can cause fouling and plugging of furnace
components.
-The temperature of the return air to the furnace is maintained between 55°F (13°C) and 80°F (27°C), with no evening setback or
shutdown. The use of the furnace while the structure is under construction is deemed to be intermittent operation per our installation
instructions.
-The air temperature rise is within the rated rise range on the furnace rating plate, and the firing rate has been set to the nameplate value.
-The filters used to clean the circulating air during the construction process must be either changed or thoroughly cleaned prior to
occupancy.
-The furnace, ductwork and filters are cleaned as necessary to remove drywall dust and construction debris from all HVAC system
components after construction is completed.
-After construction is complete, verify furnace operating conditions including ignition, input rate, temperature rise and venting, according
to the manufacturer’s instructions.
CAUTION: UNIT DAMAGE HAZARD
Failure to follow this caution may result in minor
property or unit damage.
If this furnace is installed in an unconditioned space
where the ambient temperatures may be 32°F or lower,
freeze protection measures must be taken. (See Fig. 15.)
II. FURNACE LOCATION RELATIVE TO COOLING
EQUIPMENT
The cooling coil must be installed parallel with or on downstream
side of furnace to avoid condensation in heat exchanger. When
installed parallel with a furnace, dampers or other means used to
control flow of air must prevent chilled air from entering furnace.
If dampers are manually operated, they must be equipped with a
means to prevent operation of either unit unless the damper is in
full-heat or full-cool position.
Fig. 14—Prohibit Installation on Back
A93043
FRONT
BACK
FRONT
B
A
C
K
Fig. 15—Freeze Protection
A93058
32°F MINIMUM INSTALLED
AMBIENT OR FREEZE
PROTECTION REQUIRED
—14—
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