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High Altitude Derate
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. Contact your
distributor for a tabular listing of appropriate altitude ranges and
corresponding manufacturer's high altitude (Natural, propane
gas, and/or pressure switch) kits.
NOTE: 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
and the altitude. Refer to the National Fuel Gas Code, NFPA 54/
ANSI Z223.1, 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
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content of the fuel used. Contact your
distributor for a tabular listing of appropriate altitude ranges and
corresponding manufacturer's pressure switch kits.
Propane Gas Conversion
WARNING
Possible property damage, personal injury or death may
occur if the correct conversion kits are not installed. The
Placeholder
appropriate kits must be applied to ensure safe and proper
furnace operation. All conversions must be performed by
a qualified installer or service agency.
This furnace is configured for Natural gas. The appropriate
manufacturer's propane gas conversion kit, must be applied for
propane gas installations. See "Propane Gas and/or High Altitude
Installations."
Contact your distributor for a tabular listing of appropriate
manufacturer's kits for propane gas and/or high altitude
installations. The indicated kits must be used to ensure safe and
proper furnace operation. All conversions must be performed by
a qualified installer or service agency.
Gas Control Valve
This furnace is equipped with a 24-volt gas control valve
controlled during the furnace operation by the integrated control
module. As shipped, the gas control valve is configured for
Natural gas. The gas control 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 control valve has a manual On/Off control located on the
gas control valve itself. This control may be set only to the "On"
or "Off" position.
Refer to the lighting instructions label or see "Start-Up Procedure
and Adjustment" for use of this control during the start-up and
shutdown periods.
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content of the derated gas
Gas Piping Connections
CAUTION
To avoid possible unsatisfactory operation or equipment
damage due to underfiring of equipment, use the proper
Placeholder
size of Natural/propane gas piping needed when running
pipe from the meter/tank to the furnace.
When sizing a trunk line, be sure to include all appliances which
will operate simultaneously when sizing a trunk line.
The gas piping supplying the furnace must be properly sized
based on the gas flow required, specific gravity of the gas and
the 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—Cu ft of Gas Per Hour (CFH)
Length of
Nominal Black Pipe Size
Pipe—
¹⁄₂ "
³⁄₄ "
ft (m)
10 (3)
132
278
20 (6.1)
92
190
30 (9.2)
73
152
40 (12.2)
63
130
50 (15.2)
56
115
60 (18.3)
50
105
70 (21.3)
46
96
80 (24.4)
43
90
90 (27.4)
40
84
100 (30.5)
38
79
Pressure 0.5 psig or less and pressure drop of 0.3" W.C.; based
on 0.60 specific gravity gas
Btu/h Furnace Input
CFH =
Heating Value of Gas (Btu/cu ft
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 the gas control valve. In some
cases, the installer may also need to supply a transition piece
from ¹⁄₂" (1.3 cm) pipe to a larger pipe size.
The following stipulations apply when connecting gas piping.
Refer to "Gas Piping Connections" illustrations for typical gas line
connections to the furnace.
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.
NOTE: 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 (pipe dope) on male threads only.
Always use pipe joint compound (pipe dope) that is approved
for all gases.
NOTE: Do not apply compound to the first 2 threads.
Use ground joint unions.
Install a drip leg to trap dirt and moisture before it can enter
the gas control valve. The drip leg must be a minimum of 3"
(7.6 cm) long.
1"
1¹⁄₄ "
1¹⁄₂ "
520
1,050
1,600
350
730
1,100
285
590
980
245
500
760
215
440
670
195
400
610
180
370
560
170
350
530
160
320
490
150
305
460
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