INSTALLATION INSTRUCTIONS
Gas Furnace: (F/G)MAC
440 01 4201 01
25
Specifications subject to change without notice.
Air Ducts
General Requirements
The duct system should be designed and sized according to
accepted national standards such as those published by: Air
Conditioning Contractors Association (ACCA), Sheet Metal and
Air Conditioning Contractors National Association (SMACNA)
or American Society of Heating, Refrigerating and Air
Conditioning Engineers (ASHRAE) or consult
The Air Systems
Design Guidelines
reference tables available from your local
distributor. The duct system should be sized to handle the
required system design CFM at the design external static
pressure. The furnace airflow rates are provided in the Service
and Technical Manual, Air Delivery
−
CFM (with filter). When a
furnace is installed so that the supply ducts carry air circulated
by the furnace to areas outside the space containing the
furnace, the return air shall also be handled by duct(s) sealed
to the furnace casing and terminating outside the space
containing the furnace.
Secure ductwork with proper fasteners for type of ductwork
used. Seal supply
−
and return
−
duct connections to furnace
with code approved tape or duct sealer.
NOTE
: Flexible connections should be used between ductwork
and furnace to prevent transmission of vibration.
Ductwork passing through unconditioned space should be
insulated to enhance system performance. When air
conditioning is used, a vapor barrier is recommended.
Maintain a 1
−
in. (25 mm) clearance from combustible materials
to supply air ductwork for a distance of 36
−
in. (914 mm)
horizontally from the furnace. See NFPA 90B or local code for
further requirements.
Ductwork Acoustical Treatment
NOTE
: Metal duct systems that do not have a 90 degree elbow
and 10 ft. (3 M) of main duct to the first branch take
−
off may
require internal acoustical lining. As an alternative, fibrous
ductwork may be used if constructed and installed in
accordance with the latest edition of SMACNA construction
standard on fibrous glass ducts. Both acoustical lining and
fibrous ductwork shall comply with NFPA 90B as tested by UL
Standard 181 for Class 1 Rigid air ducts.
NOTE
: For horizontal applications, the top most flange may be
bent past 90
to allow the evaporator coil to hang on the
flange temporarily while the remaining attachment and sealing
of the coil are performed.
GAS PIPING
!
WARNING
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
Never purge a gas line into a combustion chamber.
Never test for gas leaks with an open flame. Use a
commercially available soap solution made specifically
for the detection of leaks to check all connections. A
fire or explosion may result causing property damage,
personal injury or loss of life.
!
WARNING
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
Use proper length of pipe to avoid stress on gas con-
trol manifold and a gas leak.
!
WARNING
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
Gas valve inlet and/or inlet pipe must remain capped
until gas supply line is permanently installed to protect
the valve from moisture and debris. Also, install a sedi-
ment trap in the gas supply piping at the inlet to the
gas valve.
Gas piping must be installed in accordance with national and
local codes. Refer to current edition of NFGC in the U.S.A.
Refer to current edition of CAN/CSA B149.1 in Canada.
Installations must be made in accordance with all authorities
having jurisdiction. If possible, the gas supply line should be a
separate line running directly from meter to furnace.
NOTE
: Use a back
−
up wrench on the inlet of the gas valve
when connecting the gas line to the gas valve.
NOTE
: In the state of Massachusetts:
1. Gas supply connections MUST be performed by a
licensed plumber or gas fitter.
2. When flexible connectors are used, the maximum length
shall not exceed 36
−
in. (915 mm).
3. When lever handle type manual equipment shutoff
valves are used, they shall be T
−
handle valves.
4. The use of copper tubing for gas piping is NOT approved
by the state of Massachusetts.
Refer to
Table 8
for recommended gas pipe sizing. Risers must
be used to connect to furnace and to meter. Support all gas
piping with appropriate straps, hangers, etc. Use a minimum of
one hanger every 6 ft. (1.8 M). Joint compound (pipe dope)
should be applied sparingly and only to male threads of joints.
Pipe dope must be resistant to the action of propane gas.
!
WARNING
FIRE OR EXPLOSION HAZARD
A failure to follow this warning could result in personal in-
jury, death, and/or property damage.
If local codes allow the use of a flexible gas appliance
connector, always use a new listed connector. Do not use
a connector which has previously served another gas ap-
pliance. Black iron pipe shall be installed at the furnace
gas control valve and extend a minimum of 2
−
in. (51 mm)
outside the furnace.
!
CAUTION
FURNACE DAMAGE HAZARD
Failure to follow this caution may result in furnace dam-
age.
Connect gas pipe to furnace using a backup wrench to
avoid damaging gas controls and burner misalignment.
