Goodman MEC96 Series Instruction Manual page 27

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 prop-
er 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
gas 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
the furnace Specification Sheet for pressure switch.
P
OSSIBLE PROPERTY DAMAGE
OCCUR IF THE CORRECT CONVERSION KITS ARE NOT INSTALLED
APPROPRIATE KITS MUST BE APPLIED TO ENSURE SAFE AND PROPER
. A
FURNACE OPERATION LL CONVERSIONS MUST BE PERFORMED BY A
QUALIFIED INSTALLER OR SERVICE AGENCY
Propane Gas Conversion
This unit is configured for natural gas, but may be converted
for use with L.P. gas. Refer to the section on PROPANE GAS/
HIGH ALTITUDE INSTALLATIONS for L.P. kit selection.
Consult the furnace Specification Sheet for a listing of appro-
priate 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.
T
O PREVENT UNRELIABLE OPERATION OR EQUIPMENT DAMAGE
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 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 appro-
priate 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
content of the derated
3
content of the fuel used. Consult
3
WARNING
,
PERSONAL INJURY OR DEATH MAY
.
CAUTION
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 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.
Length of
Pipe in Feet
10
20
30
40
50
60
70
80
90
100
(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)
. T
HE
To connect the furnace to the building's gas piping, the install-
er 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,
,
THE
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 GASES. DO NOT apply
compound to the first 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 fitting, 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.
27
Natural Gas Capacity of Pipe
In Cubic Feet of Gas Per Hour (CFH)
Nominal Black Pipe Size
1/2" 3/4" 1"
132 278 520
92 190 350
73 152 285
63 130 245
56 115 215
50 105 195
46 96 180
43 90 170
40 84 160
38 79 150
1 1/4" 1 1/2"
1050 1600
730 1100
590 980
500 760
440 670
400 610
370 560
350 530
320 490
305 460