GMS8 Installation Manual
17
24 VOLT THERM OSTAT W IRING
NOTE: Wire routing must not interfere with circulator blower
operation, filter removal, or routine maintenance.
Low voltage connections can be made through either the right or
left side panel. Thermostat wiring entrance holes are located in
the blower compartment. The following figure shows connections
for a “ heat only” system and “heat/ cool system”.
Furnace
Control
Furnace
Control
Remote
Condensing
Unit
Heatin
g
Room
Thermostat
Heating/Cooling
Room Thermostat
WW
Typical Field Wiring (24 VAC Control Circuit)
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.
A single-stage thermostat with only one heating stage can be used
to control this furnace.
GM E8 & AM EH8 FURNACES W ITH 2-STAGE CONDENSER FIELD
WIRING
The GME8 and AMEH8 model furnaces may be used with a 2-stage
outdoor air conditioner. A two stage cooling/single stage gas heat
thermostat is required, in addition to a field supplied relay. The
relay must have a 24VAC coil and contacts rated for up to 1 horse
power at 125VAC.
1. Install the field supplied relay on the control mounting panel
near the furnace ignition control. The relay should be in-
stalled such that the motor leads will reach the relay contact
terminals.
2. Connect the “Y2” (high stage cool) thermostat terminal to one
coil terminal of the field supplied relay. Connect the other
field supplied relay coil terminal to the “ C” terminal on the
furnace ignition control. Typical 18AWG thermostat wire may
be used.
3. Connect the common terminal of the field supplied relay to the
“ LINE-H” terminal on the furnace ignition control. Use wiring
having copper conductors only and a temperature rating of at
least 105°C.
4. Using the GM E8 airflow tables in this manual, determine the
motor speed tap needed to deliver the required high stage
cooling airflow. Connect the selected motor speed tap to the
normally open terminal on the field supplied relay. Use wiring
having copper conductors only and a temperature rating of at
least 105°C.
5. See the wiring schematic below.
Furnace
Control
Remote Condensing Unit
Heating/Cooling
Room Thermostat
Y
Y1
Y1 Y2
Lo-Heat
Hi-Heat
Cool
Line-H
T4
T2
T3
T5
ECO-TECH
MOTOR
Field
Supplied
Relay
Y2
Field Wiring for GME8 & AMEH8 Furnaces
with 2-Stage Condenser
SETTING THE HEAT ANTICIPATOR
The heat anticipator in older, non electronic room thermostats
must be adjusted correctly to obtain the proper number of cycles
per hour and to prevent “overshooting” the setting. Set the heat
anticipator setting to 0.7 amps. Follow the thermostat
manufacturer ’s instructions on how to adjust the heat anticipa-
tor.
115 VOLT LINE CONNECTION OF ACCESSORIES
ELECTRONIC AIR CLEANER
(GM E8, AM EH8, GDH8, ADSH8 & (A/ G)M H8 M ODELS ONLY)
HIGH VOLTAGE !
T
O
AVOID
PERSONAL
INJURY
OR
DEATH
DUE
TO
ELECTRICAL
SHOCK
,
DISCONNECT
ELECTRICAL
POW ER
BEFORE
SERVICING
OR
CHANGING
ANY
ELECTRICAL
W IRING
.
WARNING
The furnace integrated control module is equipped with line volt-
age accessory terminals for controlling power to an optional field-
supplied electronic air cleaner.
The accessory load specifications are as follows:
Electronic Air Cleaner 1.0 Amp maximum at 120 VAC
Turn OFF power to the furnace before installing any accessories.
Follow the air cleaner manufacturers’ instructions for locating,
mounting, grounding, and controlling these accessories. Acces-
sory wiring connections are to be made through the 1/4" quick
connect terminals provided on the furnace integrated control
module. The electronic air cleaner hot terminal is identified as
EAC-H and the neutral terminal is identified as NEUTRAL. All field
wiring must conform to applicable codes. Connections should be
made as shown in the following illustration.