035-17468-001 Rev. A (801)
Unitary Products Group
11
GAS PIPING
The gas supply should be a separate line and must be
installed in accordance with the National Fuel Gas Code,
ANSI Z223.1 (latest edition), or the CAN/CGA B149.1 or .2
Installation Codes (latest edition) and all applicable local and
utility requirements.
Some utility companies or local codes require pipe sizes
larger than the minimum sizes listed in these instructions and
in the codes. Properly sized wrought iron, approved flexible
or steel pipe must be used when making gas connections to
the unit. The installation of a drop leg and ground union is
required (Refer to Figure 10).
Gas piping may be connected from either side of the furnace
using any of the gas pipe entry knockouts on both sides of
the furnace (Refer to Figure 1 for locations and dimensions).
NOTE:
Plan your combustion air piping before determining
the correct gas pipe entry. Use 90 degree service elbow(s), or
short nipples and conventional 90 degree elbow(s) to enter
through the cabinet access holes.
NOTE:
An accessible manual shutoff valve must be installed
upstream of the furnace gas controls and within 6 feet of the
furnace.
NOTE:
A 1/8” NPT plug is included in the inlet side of the gas
valve for measuring incoming gas pressure.
The furnace must be isolated from the gas supply piping sys-
tem by closing its individual external manual shutoff valve
during any pressure testing of the gas supply piping system
at pressures equal to or less than 1/2 psig (3.48 kpa).
The furnace and its individual shutoff valve must be discon-
nected from the gas supply piping system during any pres-
sure testing of that system at test pressures in excess of 1/2
psig (3.48 kpa).
FIGURE 9 :
Typical Furnace Installation Using
Suspension Materials
In any application where temperatures below freez-
ing are possible, See “BELOW FREEZING LOCA-
TIONS” on page 4.
INLET GAS PRESSURE RANGE
NATURAL GAS
PROPANE (LP)
Minimum
4.5 In. W.C.
11 In. W.C.
Maximum
13.8 In. W.C.
13.8 In. W.C.
1” MAX. BETWEEN
ROD & FURNACE
SUPPORT
ROD
6” MIN BETWEEN
ROD & FURNACE
1” MAX. BETWEEN
ROD & FURNACE
ANGLE IRON
BRACKET
An overpressure protection device, such as a pres-
sure regulator, which conforms to the National Fuel
Gas Code, ANSI Z223.1 (U.S.) or CAN-B149.1 or .2
(Canada) and acts to limit the downstream pressure
to a value that does not exceed 0.5 PSI (14” w.c.),
must be installed in the gas piping system upstream
of the furnace. Failure to do so may result in a fire or
explosion or cause damage to the furnace or some
of its components.
FIGURE 10 :
Gas Piping
Never apply a pipe wrench to the body of the combi-
nation automatic gas valve. A wrench must be
placed on the projection or wrench boss of the valve
when installing piping to it.
GAS VALVE
TO GAS
SUPPLY
EXTERNAL MANUAL
SHUTOFF VALVE
TO GAS
SUPPLY
DROP LEG
GROUND JOINT UNION
MAY BE INSTALLED
INSIDE OR OUTSIDE UNIT
