26
This furnace is equipped with a 40 VA transformer to
facilitate use with most cooling equipment. Consult the
wiring diagram, located on the blower compartment door,
for further details of 115 Volt and 24 Volt wiring.
R
Y
C
Furnace Integrated
Control Module
Remote Condensing Unit
(Single-Stage Cooling)
R
Room
Thermostat
Figure 30
Single-Stage Heating Thermostat Application
A single-stage thermostat with only one heating stage is
needed to control this furnace.
Fossil Fuel Applications
This furnace can be used in conjunction with a heat pump
in a fossil fuel application. A fossil fuel application refers to a
combined gas furnace and heat pump installation which uses
an outdoor temperature sensor to determine the most cost
efficient means of heating (heat pump or gas furnace).
Strictly follow the wiring guidelines in the fossil fuel kit
installation instructions. All furnace connections must be
made to the furnace two-stage integrated control module and
the “FURNACE” terminal strip on the fossil fuel control board.
GAS SUPPLY AND PIPING
WARNING
Possible property damage, personal injury or death may
occur if the correct conversion kits are not installed. The
appropriate kits must be applied to ensure safe and proper
furnace operation. All conversions must be performed by a
qualified installer or service agency.
WARNING
To avoid possible unsatisfactory by 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.
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.
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.
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. 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/ft3 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/ft3 content of the fuel used. Consult
the furnace Specification Sheet for pressure switch.
Propane Gas Conversion
This unit is configured for natural gas. To operate this furnace
on L.P. gas, an LPM-07 LP Conversion kit must be used.
The indicated kit must be used to insure safe and proper
furnace operation. All conversions must be performed by a
qualified installer, or service agency.
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
appropriate manufacturer’s propane gas conversion kit.
Taps for measuring the gas supply pressure and manifold
pressure are provided on the valve.
