Install Instructions

28
Inlet gas supply pressures must be maintained within
the ranges specied in the following table. The supply
pressure must be constant and available with all other
household gas red appliances operating. The minimum
gas supply pressure must be maintained to prevent
unreliable ignition. The maximum must not be exceeded
to prevent unit overring.
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 .


When this furnace is installed at high altitude, the
appropriate High Altitude Kit including orices and a
pressure switch(s) must be installed. These changes are
necessary to compensate for the natural reduction in the
density of both the gas fuel and the combustion air at
higher altitude.
Installation of this furnace at altitudes above 7000 ft (2134
m), shall be made in accordance with the Listed High
Altitude Conversion Kit available with this furnace.
Do not de-rate the furnace by adjusting the manifold
pressure to a lower pressure than specied on the furnace
rating plate. The combination of the lower air density and
a lower manifold pressure will prohibit the burner orice
from drawing the proper amount of air into the burner. This
may cause incomplete combustion, ashback, and yellow
tipping.
In some areas the gas supplier may articially derate the
gas in an e󰀨ort to compensate for the e󰀨ects of altitude.
If the gas is articially derated, the appropriate orice size
must be determined based upon the BTU/ft³ content of
the derated 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
orice size. A di󰀨erent pressure switch may be required
at high altitude regardless of the BTU/ft³ content of the
fuel used. Consult the furnace Specication Sheet. All
conversions must be performed by a qualied installer, or
service agency.

This furnace is shipped from the factory congured for
natural gas at standard altitude. To operate this furnace
on L.P. gas, a LPM-07 LP Conversion kit must be used.
Propane gas installations require an orice and spring
change to compensate for the energy content di󰀨erence
between natural and propane gas.

Two furnaces of the same model may be twinned. The
integrated control board has a 3/16” terminal labeled
“TWIN” located beside the low voltage thermostat
connection strip. Twinning allows simultaneous operation
of two furnaces and forces the indoor blower motors of
each furnace to operate synchronously into a common
duct system. Using the twinning function will require only
eld installed wiring with no external kits or parts. The
staging and speed tap options must be set the same on
both furnaces.




the furnaces are in phase, check from L1 to L1 on each


ROOM THERMOSTAT
Y2
Y/Y1
C
G
R
W
Y2
Y/Y1
C
G
R
W
Y2
Y/Y1
C
G
R
W
TWIN
TWIN
COND UNIT
CONTACTOR
COND UNIT
CONTACTOR
FURNACE 1
FURNACE 2

T O PREVENT UNRELIABLE OPERATION OR EQUIPMENT DAMAGE , THE
GAS MANIFOLD PRESSURE MUST BE AS SPECIFIED ON THE UNIT RATING
PLATE . O NLY MINOR ADJUSTMENTS SHOULD BE MADE BY ADJUSTING
THE GAS VALVE PRESSURE REGULATOR .


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 .

Natural Gas Minimum: 4.5" w.c. Maximum: 10.0" w.c.
Propane Gas Minimum: 11.0" w.c. Maximum: 13.0" w.c.

The furnace rating plate includes the approved furnace gas
input rating and gas types. The furnace must be equipped
to operate on the type of gas applied. This includes any
conversion kits required for alternate fuels and/or high
altitude.