GMES80 Installation Manual

14

Furnaces may be twinned without the use of a twinning
kit. Furnaces must be the same model and equipped with
PCBBF145 control boards. Follow the diagram provided
in this manual. Connection of the “twin” terminals of each
control together will allow simultaneous operation of two or
more furnace indoor blowers to operate synchronously on a
common duct system. Field installed low voltage thermostat
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.
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
.
CAUTION
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
.

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 con-
version kits required for alternate fuels and/or high altitude.
NOTE: Do no remove the gas valve inlet plug before the gas
line is installed. Replace if water or debris has been introduced.
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 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 pres-
sure must be maintained to prevent unreliable ignition. The
maximum must not be exceeded to prevent unit overring.
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. Overring of the fur nace can result in
premature heat exchanger failure. Gas pressures in excess
of 13 inch es 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 Specication Sheet applicable to your
model for the fuel used. At all altitudes and with either fuel,
the air tempera ture 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.

IMPORTANT NOTE: The furnace, as shipped, requires
no change to run between 0 - 5500 feet. Do not attempt to
increase the r ing rate by changing orices 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 orice 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 distrib-
utor for required kit(s).
All conversions must be performed by a qualied installer, or
service agency.

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 congured for natural gas but may be converted for
use with L.P. gas by installing the specied 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 ring when the LP gas supply pressure is too low to
support proper combustion.
Altitude Gas Kit Orifice
Manifold
Pressure
Pressure
Sw itch
#55
10.0" w .c.
0 - 5500
Natural
None
#45
3.5" w .c.
None
Propane
LPT-03