Installation manual

035-19599-001 Rev. A (1103)
Unitary Products Group 5
1. The Air Temperature Rise is determined by subtracting the Return
Air Temperature Reading from the Supply Air Temperature Read-
ing.
2. The External Static Pressure is determined by adding the Supply
Duct Static Pressure reading to the Return Duct Static Pressure
reading.
TABLES 2 AND 3 are to be used as a guide only to help the installer
determine if the duct sizes are large enough to obtain the proper air flow
(CFM) through the furnace. TABLES 2 and 3 ARE NOT to be used to
design ductwork for the building where the furnace is being installed.
There are several variables associated with proper duct sizing that are
not included in the tables. To properly design the ductwork for the build-
ing, Refer to the ASHRAE Fundamentals Handbook, Chapter on
“DUCT DESIGN” or a company that specializes in Residential and Mod-
ular Home duct designs.
IMPORTANT: If the supply air duct is being connected to the furnace
without the use of an accessory duct connector, then a transition duct
must be installed with flanges or tabs that are securely attach and
sealed to the supply air duct and to the base of the furnace. The transi-
tion duct must have R-40 insulation between the transition duct and any
combustible material.
The transition duct must be the same dimensional size as the rectangu-
lar opening in the base of the furnace.
Downflow Air Conditioning Coil Cabinet
The furnace should be installed with coil cabinet part number specifi-
cally intended for downflow application. If a matching cooling coil is
used, it may be placed directly on the furnace outlet and sealed to pre-
vent leakage. For details of the coil cabinet dimensions and installation
requirements, refer to the installation instructions supplied with the coil
cabinet.
The perforations in the wrapper flanges must be bent away from the
heat exchanger to create duct flanges so the air conditioning coil can be
properly seated on the furnace. Attach the air conditioning coil cabinet
to the duct connector, and then position the furnace on top of the coil
cabinet. The connection to the furnace, air conditioning coil cabinet,
duct connector, and supply air duct must be sealed to prevent air leak-
age.
IMPORTANT: On all installations without a coil, a removable access
panel is recommended in the outlet duct such that smoke or reflected
light would be observable inside the casing to indicate the presence of
leaks in the heat exchanger. This access cover shall be attached in
such a manner as to prevent leaks.
Horizontal Models
Horizontal Installations With a Cooling Coil Cabinet
The furnace should be installed with coil cabinet part number specifi-
cally intended for Horizontal application. If a matching cooling coil is
used, it may be placed directly on the furnace outlet and sealed to pre-
vent leakage. Follow the coil instructions for installing the supply ple-
num. For details of the coil cabinet dimensions and installation
requirements, refer to the installation instructions supplied with the coil
cabinet
The perforations in the wrapper flanges must be bent away from the
heat exchanger to create duct flanges so the air conditioning coil can be
properly seated on the furnace.
Attach the supply plenum to the air conditioning coil cabinet outlet duct
flanges through the use of S cleat material when a metal plenum is
used. The use of an approved flexible duct connector is recommended
on all installations. The connection to the furnace, air conditioning coil
cabinet and the supply plenum should be sealed to prevent air leakage.
The sheet metal should be crosshatched to eliminate any popping of
the sheet metal when the indoor fan is energized.
The minimum plenum height is 12” (30.5 cm). If the plenum is shorter
than 12” (30.5 cm) the turbulent air flow may cause the limit controls not
to operate as designed, or the limit controls may not operate at all. Also
the plastic drain pan in the under the air conditioning coil can overheat
and melt Refer to the installation instructions supplied with the air condi-
tioning coil for additional information.
FIGURE 1 : Combustible Floor Base Accessory
The supply air temperature MUST NEVER exceed the Maximum
Supply Air Temperature, specified on the nameplate.
Operating the furnace above the maximum supply air temperature
will cause the heat exchanger to overheat, causing premature heat
exchanger failure. Improper duct sizing, dirty air filters, incorrect
manifold pressure, incorrect gas orifice and a faulty limit switch can
cause the furnace to operate above the maximum supply air tem-
perature. Refer to sections II, III and XI for additional information on
correcting the problem.
DOWNFLOW
FURNACE
WARM AIR PLENUM
WITH 1” FLANGES
FIBERGLASS
INSULATION
FIBERGLASS TAPE
UNDER FLANGE
COMBUSTIBLE FLOOR
BASE ACCESSORY