Installation Guide
15
more furnace indoor blowers to operate synchronously on a
common duct system. Field installed low voltage thermo-
stat wiring, 3/16” terminals are required to make this
connection. An isolating relay (24 VAC coil & N/O SPST)
contacts is also required if the furnaces are not fed from
the same line voltage phase. A pulsing DC signal is used to
share the call for fan operation between furnaces. The
duration of the pulse width determines the speed that the
reading control will energize its blower motor.
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
appliances operating. The minimum gas supply pressure must be
maintained to prevent unreliable ignition. The maximum must not
be exceeded to prevent unit overfiring.
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
IMPORTANT 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 necessary
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).
All conversions must be performed by a qualified installer, or
service agency.
PROPANE G AS C ONVERSION
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 but may be converted for
use with L.P. gas by installing the specified L.P. conversion kit.
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.
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
All conversions must be performed by a qualified installer, or
service agency.
GAS P IPING C ONNECTIONS
T
O
AVOID
POSSIBLE
UNSATISFACTORY
OPERATION
PMENT
,
USE
THE
PROPER
SIZE
OF
NATURAL
/
PROPANE
GAS
PIPING
NEEDED
WHEN
RUNNING
PIPE
FROM
THE
METER
/
TANK
TO
THE
FURNACE
.
OR
EQUIPMENT
DAMAGE
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.