Installation Guide
25
NEUTRAL
HUM-OUT
HUM-IN
Figure 33A
24 VOLT
COMMON
HUM-OUT
HUM-IN
Figure 33B
AUXILIARY ALARM SWITCH:
The control is equipped with a 24VAC Auxiliary Alarm Input
(12 inch purple / white wire attached to pin 6 of 15 pin
connector) which can be utilized with communicating mode
setups (typically used for condensate switch wiring but could
be used with compatible C0
2
sensors or Fire Alarms).
Legacy mode use
In a legacy system (Non-communicating), this auxiliary alarm
input is not operational. Any auxiliary alarm switch must be
used to interrupt Y1 signal either to IFC or to UC.
Communication mode use
This feature can be activated or deactivated through the
thermostat user menus. By default, an AUX switch is nor-
mally closed and opens when the water level in the evapora-
tor coil base pan reaches a particular level. The control will
respond by turning off the outdoor compressor and display
the proper fault codes. If the AUX switch is detected closed
for 30 seconds, normal operation resumes and error mes-
sages are no longer displayed. Installer must wire control
voltage (24VAC) to AUX switch to ensure the Auxiliary Alarm
Input has 24VAC during normal operation.
G
AS
S
UPPLY
AND
P
IPING
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.
CAUTION
T
O
PREVENT
UNRELIABLE
OPERATION
OR
EQUIPMENT
DAMAGE
,
THE
INLET
GAS
SUPPLY
PRESSURE
MUST
BE
AS
SPECIFIED
ON
THE
UNIT
RATING
PLATE
WITH
ALL
OTHER
HOUSEHOLD
GAS
FIRED
APPLIANCES
OPERATING
.
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 appli-
ances operating. The minimum gas supply pressure must be
maintained to prevent unreliable ignition. The maximum must
not be exceeded to prevent unit overfiring.
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
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 pres-
sure will prohibit the burner orifice from drawing the proper
amount of air into the burner. This may cause incomplete com-
bustion, 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 deter-
mined based upon the BTU/ft
3
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 deter-
mine the proper orifice size.
A different pressure switch may be required at high altitude
regardless of the BTU/ft
3
content of the fuel used. Consult the
furnace Specification Sheet for pressure switch.
PROPANE GAS CONVERSION
WARNING
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
.
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 for details.
Consult the furnace Specification Sheet for a listing of ap-
propriate 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.