Installation Guide
22
• Use black iron or steel pipe and fi ttings for building
piping. Where possible, use new pipe that is properly
chamfered, reamed, and free of burrs and chips. If old
pipe is used, be sure it is clean and free of rust, scale,
burrs, chips, and old pipe joint compound.
• Use pipe joint compound on male threads ONLY.
Always use pipe joint compound (pipe dope) that is
APPROVED FOR ALL GASSES. DO NOT apply
compound to the fi rst two threads.
• Use ground joint unions.
• Install a drip leg to trap dirt and moisture before it can
enter the gas valve. The drip leg must be a minimum
of three inches long.
• Install a 1/8” NPT pipe plug fi tting, accessible for test
gage connection, immediately upstream of the gas
supply connection to the furnace.
• Always use a back-up wrench when making the
connection to the gas valve to keep it from turning.
The orientation of the gas valve on the manifold must
be maintained as shipped from the factory. Maximum
torque for the gas valve connection is 375 in-lbs;
excessive over-tightening may damage the gas valve.
• Install a manual shutoff valve between the gas meter
and unit within six feet of the unit. If a union is installed,
the union must be downstream of the manual shutoff
valve, between the shutoff valve and the furnace.
• Tighten all joints securely.
• Connect the furnace to the building piping by one of the
following methods:
– Rigid metallic pipe and fi ttings.
– Semi-rigid metallic tubing and metallic fi ttings.
Aluminum alloy tubing must not be used in exterior
locations. In order to seal the grommet cabinet
penetration, rigid pipe must be used to reach the
outside of the cabinet. A semi-rigid connector to
the gas piping may be used from there.
• Use listed gas appliance connectors in accordance with
their instructions. Connectors must be fully in the same
room as the furnace.
• Protect connectors and semirigid tubing against
physical and thermal damage when installed. Ensure
aluminum-alloy tubing and connectors are coated to
protect against external corrosion when in contact with
masonry, plaster, or insulation, or subjected to repeated
wetting by liquids such as water (except rain water),
detergents, or sewage.
The gas piping may enter the left or right side of the furnace
cabinet. The installer must supply rigid pipe long enough to reach
the outside of the cabinet to seal the grommet cabinet penetration.
A semi-rigid connector to the gas piping can be used outside the
cabinet per local codes. 1/2” NPT pipe and fi ttings are required.
For models with an “L” shaped manifold, a 4 1/2” long nipple
is required. For models with a hook shaped manifold, a 2”
proper furnace operation. All conversions must be performed
by a qualifi ed installer, or service agency.
CAUTION
T
O
PREVENT
UNRELIABLE
OPERATION
OR
EQUIPMENT
DAMAGE
,
THE
INLET
GAS
SUPPLY
PRESSURE
MUST
BE
AS
SPECIFIED
ON
THE
UNIT
RATING
PLATE
WITH
ALL
OTHER
HOUSEHOLD
GAS
FIRED
APPLIANCES
OPERATING
.
GAS VALVE
This unit is equipped with a 24 volt gas valve controlled during
furnace operation by the integrated control module. As shipped,
the valve is confi gured for natural gas. The valve is fi eld convertible
for use with propane gas by replacing the regulator spring with a
propane gas spring from an appropriate manufacturer’s propane
gas conversion kit. Taps for measuring the gas supply pressure
and manifold pressure are provided on the valve.
The gas valve has a manual ON/OFF control located on the valve
itself. This control may be set only to the “ON” or “OFF” position.
Refer to the lighting instructions label or Startup Procedure &
Adjustment for use of this control during start up and shut
down periods.
GAS PIPING CONNECTIONS
The gas piping supplying the furnace must be properly sized based
on the gas fl ow required, specifi c gravity of the gas, and length of
the run. The gas line installation must comply with local codes, or
in their absence, with the latest edition of the National Fuel Gas
Code, NFPA 54/ANSI Z223.1.
Natural Gas Capacity of Pipe
In Cubic Feet of Gas Per Hour (CFH)
Length of Nominal Black Pipe Size
Pipe in Feet 1/2" 3/4" 1" 1 1/4" 1 1/2"
10 132 278 520 1050 1600
20 92 190 350 730 1100
30 73 152 285 590 980
40 63 130 245 500 760
50 56 115 215 440 670
60 50 105 195 400 610
70 46 96 180 370 560
80 43 90 170 350 530
90 40 84 160 320 490
100 38 79 150 305 460
(Pressure 0.5 psig or less and pressure drop of 0.3" W.C.; Based on
0.60 Specific Gravity Gas)
CFH =
BTUH Furnace Input
Heating Value of Gas (BTU/Cubic Foot)
To connect the furnace to the building’s gas piping, the installer
must supply a ground joint union, drip leg, manual shutoff valve,
and line and fi ttings to connect to gas valve. In some cases, the
installer may also need to supply a transition piece from 1/2” pipe
to a larger pipe size.
The following stipulations apply when connecting gas piping.
Refer to Gas Piping Connections fi gure for typical gas line
connections to the furnace.
• Gas piping must be supported external to the furnace
cabinet so that the weight of the gas line does not distort
the burner rack, manifold or gas valve.