Downflow Furnaces; Supply Air Connections; Acoustical Treatments; Furnace Installation - Heat Controller 80+ AFUE Installation Instructions Manual

Using sharp metal cutters, cut an opening between all
4 knockouts to expose the blower assembly. Position
the return air duct over the opening and secure to the
side with sheet metal screws.
• Bottom Return Installations: If using the bottom of
the furnace for return air, the bottom panel (Figure 18)
must be removed from the bottom of the furnace. See
page 15 for removal instructions. Position the furnace
over the return air duct and secure together with sheet
metal screws. Make sure the screws penetrate the duct
and furnace casing.

Downflow Furnaces

• To attach the return air duct to the downflow furnace,
bend the flanges on the furnace upward 90° with wide
duct pliers. See Figure 18 (page 26) for furnace flange
locations. NOTE: If system installation includes AC coil
casing, bend the flanges on the coil casing upward 90°
before attaching the return air duct.
• Secure the return air ductwork to the furnace or coil
casing (if installed) with sheet metal screws. Make
sure the screws penetrate the sheet metal casing and
flanges.

Supply Air Connections

• The supply air must be delivered to the heated space
by duct(s) secured to the furnace or coil box casing,
running full size and without interruption.
• To attach the supply air duct to upflow & horizontal
furnaces, bend the flanges on the furnace upward
90° with wide duct pliers. See Figure 18 (page 26) for
furnace flange locations. NOTE: If system installation
includes AC coil casing, bend the flanges on the coil
casing upward 90° before attaching the supply air duct.
• Position the supply air ductwork onto the furnace
ensuring even alignment of furnace air opening and
supply air duct. NOTE: The ductwork must have an
opening equal to that of the supply air opening of the
furnace. See Figure 18 for supply air opening size.

Acoustical Treatments

Damping ducts, flexible vibration isolators, or pleated
media-style filters on the return air inlet of the furnace
may be used to reduce the transmission of equipment
noise eminating from the furnace. These treatments can
produce a quieter installation, particularly in the heated
space. However, they can increase the pressure drop in
the duct system. Care must be taken to maintain the proper
maximum pressure rise across the furnace, temperature
rise and flow rate. This may mean increasing the duct
size and/or reducing the blower speed. These treatments
must be constructed and installed in accordance with
NFPA and SMACNA construction standards. Consult
with local codes for special requirements. For best sound
performance, be sure to install all the needed gaskets and
grommets around penetrations into the furnace, such as
for electrical wiring.
12

FURNACE INSTALLATION

These Installation procedures are suggested for typical
furnace installations. Since each installation is different,
the sequence of instructions may differ from the actual
installation. Only qualified HVAC technicians should
install this furnace.
The installer must be familiar with and comply with all
codes and regulations applicable to the installation of
these heating appliances and related equipment. In
the absence of local codes, the installation must be in
accordance with the current provisions of one or more
of the following standards.
• American National Standard (ANSI-Z223.1/NFPA-54)
and/or CAN/CSA B149 for all gas-fired furnace models.
• American National Standard (ANSI-C1/NFPA-70) and/or
CSA 22.1 Canadian Electric Code Part 1 for all electrical
field wiring.

About The Furnace

GUH80A & GDD80A series furnaces are designed only
for indoor installations and can be readily connected to
the high static duct system of a home. GUH80A series gas
furnaces are shipped ready for installation in the upflow
or horizontal right or left positions. GDD80A series gas
furnace may only be used for downflow operation. Units
are approved for single / multistory residential structures
in freestanding /closet / alcove configurations.
This appliance will provide many years of safe and
dependable comfort, providing it is properly installed
and maintained. Abuse, improper use, and/or improper
maintenance can shorten the life of the appliance and
create unsafe hazards. Please read all instructions before
installing the unit.
Approved installation, operation, and maintenance of
this appliance must be in accordance with the listed
specifications contained in these instructions and other
documents supplied with the furnace and/or optional air
conditioning equipment. Unless it is noted differently
in this manual, only use factory authorized kits and
accessories on this appliance. Refer to local authorities
having jurisdiction for further information.

Before You Install the Furnace

√ This equipment is securely packaged at the time of
shipment and upon arrival should be carefully inspected
for damage prior to installing the equipment at the job
site. Claims for damage (apparent or concealed) should
be filed immediately with the carrier.
√ Check the electrical supply and verify the power supply
is adequate for unit operation. The system must be wired
and provided with circuit protection in accordance with
local building codes. If there is any question concerning
the power supply, contact the local power company.
√ Verify the air delivery of the furnace is adequate to
handle the static pressure drop of the coil, filter, and
duct work.