GMES8 GCES8 Installation Instructions
18
NOTE: Do not remove the gas valve inlet plug before the gas line
is installed. Replace if water or debris has been introduced.
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
NOTE: Adjusting the minimum supply pressure below the limits
in the above table could lead to unreliable ignition. Gas input to
the burners must not exceed the rated input shown on the rating
plate. Overfiring of the furnace can result in premature heat
exchanger failure. Gas pressures in excess of 13 inches water
column can also cause permanent damage to the gas valve.
At all altitudes, the manifold pressure must be within 0.3 inches
w.c. of that listed in the Specification Sheet applicable to your
model for the fuel used. At all altitudes and with either fuel, the air
temperature rise must be within the range listed on the furnace
nameplate. Should this appliance be converted to LP, refer to the
instructions included in the factory authorized LP conversion kit.
HIGH ALTITUDE DERATE
IM PORTANT NOTE: The furnace, as shipped, requires no change to
run between 0 - 5500 feet. Do not attempt to increase the firing rate
by changing orifices or increasing the manifold pressure below
5500 feet. This can cause poor combustion and equipment failure.
High altitude installations above 5500 feet may require both a
pressure switch and an orifice change. These changes are neces-
sary to compensate for the natural reduction in the density of both
the gas fuel and the combustion air at higher altitude.
For installations above 5500 feet, please refer to your distributor
for required kit(s).
Contact the distributor for a tabular listing of appropriate
manufacturer’s kits for propane gas and/ or high altitude installa-
tions. The indicated kits must be used to insure safe and proper
furnace operation. All conversions must be performed by a quali-
fied installer, or service agency.
PROPANE GAS CONVERSION
WARNING
P
OSSIBLE
PROPERTY
DAM AGE
,
PERSONAL
INJURY
OR
DEATH
M AY
OCCUR
IF
THE
CORRECT
CON VERSION
KITS
ARE
NOT
INSTALLED
. T
HE
APPROPRIATE
KITS
M UST
BE
APPLIED
TO
ENSURE
SAFE
AND
PROPER
FURNACE
OPERATION
. A
LL
CON VERSIONS
M UST
BE
PERFORM ED
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” section for details.
If converting to LP gas, it is recommended that an LPLP0* kit also
be installed. The use of this kit will prevent the furnace from firing
when the LP gas supply pressure is too low to support proper
combustion.
M odels using Single Stage Gas Valves
Altitude Gas Kit Orifice
Manifold
Pressure
Pressure
Switch
Propane LPT-03 #55 10.0" w.c.
0 - 5500
Natural None #45 3.5" w.c.
None
Contact your distributor for a tabular listing of appropriate
manufacturer ’s kits for propane gas and/or high altitude instal-
lations. The indicated kits must be used to insure safe and proper
furnace operation. All conversions must be performed by a quali-
fied installer, or service agency.
GAS PIPING CONNECTIONS
T
O
AVOID
POSSIBLE
UNSATISFACTORY
OPERATION
PM ENT
,
USE
THE
PROPER
SIZE
OF
NATURAL
/
PROPANE
GAS
PIPING
NEEDED
W HEN
RUNNING
PIPE
FROM
THE
M ETER
/
TANK
TO
THE
FURNACE
.
OR
EQUIPM ENT
DAM AGE
DUE
TO
UNDERFIRING
OF
EQUI
WARNING
When sizing gas lines, be sure to include all appliances which will
operate simultaneously.
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.
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)