66832-UIM-D-1205
4
Unitary Products Group
Installation in a residential garage:
A gas-fired furnace for installation in a residential garage must be
installed so the burner(s) and the ignition source are located not less
than (18) inches (46 cm) above the floor, and the furnace must be
located or protected to avoid physical damage by vehicles.
SECTION II: DUCTWORK
DUCTWORK GENERAL INFORMATION
The duct system’s design and installation must:
1.
Handle an air volume appropriate for the served space and within
the operating parameters of the furnace specifications.
2.
Be installed in accordance with standards of NFPA (National Fire
Protection Association) as outlined in NFPA pamphlets 90A and
90B (latest editions) or applicable national, provincial, or state, and
local fire and safety codes or in Canada, refer to the Natural Gas
and Propane Installation Code B149.1-00.
3.
Create a closed duct system. For residential and Non-HUD Modu-
lar Home installations, when a furnace is installed so that the sup-
ply ducts carry air circulated by the furnace to areas outside the
space containing the furnace, the return air shall also be handled
by a duct(s) sealed to the furnace casing and terminating outside
the space containing the furnace.
4.
Complete a path for heated or cooled air to circulate through the
air conditioning and heating equipment and to and from the condi-
tioned space.
When the furnace is used in conjunction with a cooling coil, the coil
must be installed parallel with, or in the supply air side of the furnace to
avoid condensation in the primary heat exchanger. When a parallel flow
arrangement is used, dampers or other means used to control airflow
must be adequate to prevent chilled air from entering the furnace. If
manually operated, the damper must be equipped with means to pre-
vent the furnace or the air conditioner from operating unless the damper
is in full heat or cool position.
INSTALLATION POSITION (50-125 MBH Models)
This furnace may be installed in an upflow, downflow or horizontal posi-
tion. Depending on the configuration shipped from the factory, it may be
necessary to convert the furnace from downflow to upflow or from
upflow to downflow configuration. Use conversion instructions in this
document.
INSTALLATION POSITION (150 MBH Models)
This furnace may be installed in an upflow or horizontal position. No
conversion is necessary. This furnace is not approved for downflow
application.
CONVERSION INFORMATION (50-125 MBH Models)
This furnace may be shipped in either the upflow or the downflow con-
figuration. To convert from upflow to downflow or vice-versa it is neces-
sary only to exchange the top and bottom casing caps and to rotate the
vent blower 180 degrees. Use the step by step instructions to perform
the conversion.
Downflow furnaces for installation on combustible flooring only
when installed on the accessory combustible floor base on wood
flooring only and shall not be installed directly on carpeting, tile or
other combustible material.
Check the rating plate and power supply to be sure that the electri-
cal characteristics match. All models use nominal 115 VAC, 1
Phase 60Hz power supply.
Furnace shall be installed so the electrical components are pro-
tected from water.
TABLE 1: Unit Clearances to Combustibles
APPLICATION
TOP
FRONT
REAR
SIDES SINGLE WALL VENT
FLOOR/
BOTTOM
CLOSET ALCOVE ATTIC
LINE
CONTACT
In. (cm) In. (cm) In. (cm) In. (cm)
In. (cm)
UPFLOW
1 (25.4)
2 (5.08)
0 (0.0)
0 (0.0)
6 (15.24)
COMBUSTIBLE
YES
YES
YES
NO
UPFLOW B-VENT
1 (25.4)
3 (7.62)
0 (0.0)
0 (0.0)
6 (15.24)
COMBUSTIBLE
YES
YES
YES
NO
HORIZONTAL
1 (25.4)
2 (5.08)
0 (0.0)
1 (5.08)
6 (15.24)
COMBUSTIBLE
NO
YES
YES
YES
1
1. Line contact only permitted between lines formed by the intersection of the rear panel and side panel (top in horizontal position) of the furnace jacket and building
joists, studs or framing.
HORIZONTAL B-VENT
1 (25.4)
3 (7.62)
0 (0.0)
0 (0.0)
6 (15.24)
COMBUSTIBLE
NO
YES
YES
YES
1
DOWNFLOW
1 (25.4)
2 (5.08)
0 (0.0)
0 (0.0)
6 (15.24)
NON-COMBUSTIBLE
YES
YES
YES
NO
DOWNFLOW B-VENT
1 (25.4)
3 (7.62)
0 (0.0)
0 (0.0)
6 (15.24)
NON-COMBUSTIBLE
YES
YES
YES
NO
The cooling coil must be installed in the supply air duct, down-
stream of the furnace. Cooled air may not be passed over the heat
exchanger.
The duct system must be properly sized to obtain the correct airflow
for the furnace size that is being installed.
Refer to Table 8 and the furnace rating plate for the correct rise
range and static pressures
If the ducts are undersized, the result will be high duct static pres-
sures and/or high temperature rises which can result in a heat
exchanger OVERHEATING CONDITION. This condition can result
in premature heat exchanger failure, which can result in personal
injury, property damage, or death.
