27
Inlet gas supply pressures must be maintained within the
ranges specified in the following table. The supply pressure
must be constant and available with all other household gas
fired appliances operating. The minimum gas supply
pressure must be maintained to prevent unreliable ignition.
The maximum must not be exceeded to prevent unit
overfiring.
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
.
Natural Gas
Minimum: 4.5" w.c. Maximum: 10.0" w.c.
Propane Gas Minimum: 11.0" w.c. Maximum: 13.0" w.c.
INLET GAS SUPPLY PRESSURE
H
IGH
A
LTITUDE
D
ERATE
When this furnace is installed at high altitude, the appropriate
High Altitude orifice kit must be applied. This is required
due to the natural reduction in the density of both the gas
fuel and combustion air as altitude increases. The kit will
provide the proper design certified input rate within the
specified altitude range.
High altitude kits are purchased according to the installation
altitude and usage of either natural or propane gas. Consult
the furnace Specification Sheet for appropriate kits.
Do
not
derate the furnace by adjusting the manifold pressure
to a lower pressure than specified on the furnace rating plate.
The combination of the lower air density and a lower manifold
pressure will prohibit the burner orifice from drawing the
proper amount of air into the burner. This may cause
incomplete combustion, flashback, and possible yellow
tipping.
In some areas the gas supplier may artificially derate the
gas in an effort to compensate for the effects of altitude. If
the gas is artificially derated, the appropriate orifice size
must be determined based upon the BTU/ft
3
content of the
derated gas and the altitude. Refer to the National Fuel Gas
Code, NFPA 54/ANSI Z223.1 or CAN/CSA B149.1-15 in Canada,
and information provided by the gas supplier to determine
the proper orifice size.
A different pressure switch may be required at high altitude
regardless of the BTU/ft
3
content of the fuel used. Consult
the furnace Specification Sheet for pressure switch.
P
ROPANE
G
AS
C
ONVERSION
WARNING
P
OSSIBLE
PROPERTY
DAMAGE
,
PERSONAL
INJURY
OR
DEATH
MAY
OCCUR
IF
THE
CORRECT
CONVERSION
KITS
ARE
NOT
INSTALLED
. T
HE
APPROPRIATE
KITS
MUST
BE
APPLIED
TO
ENSURE
SAFE
AND
PROPER
FURNACE
OPERATION
. A
LL
CONVERSIONS
MUST
BE
PERFORMED
BY
A
QUALIFIED
INSTALLER
OR
SERVICE
AGENCY
.
This unit is configured for natural gas. The appropriate
manufacturer’s propane gas conversion kit, must be applied
for propane gas installations. Refer to the
Propane Gas and/
or High Altitude Installations
for details.
Consult the furnace Specification Sheet for a listing of
appropriate kits. The indicated kits must be used to insure
safe and proper furnace operation. All conversions must be
performed by a qualified installer, or service agency.
G
AS
V
ALVE
This unit is equipped with a 24 volt gas valve controlled during
furnace operation by the integrated control module. As
shipped, the valve is configured for natural gas. The valve
is field 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.
G
AS
P
IPING
C
ONNECTIONS
T
O
AVOID
POSSIBLE
UNSATISFACTORY
OPERATION
OF
EQUIPMENT
DAMAGE
DUE
TO
UNDERFIRING
OR
EQUIPMENT
,
USE
THE
PROPER
SIZE
OF
NATURAL
/
PROPANE
GAS
PIPING
NEEDED
WHEN
RUNNING
PIPE
FROM
THE
METER
/
TANK
TO
THE
FURNACE
.
WARNING
The gas piping supplying the furnace must be properly sized
based on the gas flow required, specific 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 or CAN/
CSA B149.1-15.
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 fittings 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
figure 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.
•
Use black iron or steel pipe and fittings 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.
