Installation manual

ManualsBrandsUnitary products group ManualsFurnaceGF8

66832-UIM-D-1205

14 Unitary Products Group

SUPPLY VOLTAGE CONNECTIONS

1. Provide a power supply separate from all other circuits. Install

overcurrent protection and disconnect switch per local/national

electrical codes. The switch should be close to the unit for conve-

nience in servicing. With the disconnect or fused switch in the OFF

position, check all wiring against the unit wiring label. Refer to the

wiring diagram in this instruction.

2. Remove the screws retaining the wiring box cover. Route the

power wiring through the opening in the unit into the junction box

with a conduit connector or other proper connection. In the junc-

tion box there will be three wires, a Black Wire, a White Wire and a

Green Wire. Connect the power supply as shown on the unit-wir-

ing label on the inside of the blower compartment door or the wir-

ing schematic in this section. The black furnace lead must be

connected to the L1 (hot) wire from the power supply. The white

furnace lead must be connected to neutral. Connect the green fur-

nace lead (equipment ground) to the power supply ground. An

alternate wiring method is to use a field provided 2” (51 mm) x 4”

(102 mm) box and cover on the outside of the furnace. Route the

furnace leads into the box using a protective bushing where the

wires pass through the furnace panel. After making the wiring con-

nections replace the wiring box cover and screws. Refer to Figure

18.

3. The furnace's control system requires correct polarity of the power

supply and a proper ground connection. Refer to Figure 19.

IMPORTANT: The power connection leads and wiring box may be relo-

cated to the left side of the furnace. Remove the screws and cut wire tie

holding excess wiring. Reposition on the left side of the furnace and fas-

ten using holes provided.

LOW VOLTAGE CONTROL WIRING CONNECTIONS

Install the field-supplied thermostat by following the instructions that

come with the thermostat. With the thermostat set in the OFF position

and the main electrical source disconnected, connect the thermostat

wiring from the wiring connections on the thermostat to the terminal

board on the ignition module, as shown in Figure 20. Electronic thermo-

stats may require the common wire to be connected as shown with the

dashed line in Figure 20. Apply strain relief to thermostat wires passing

through cabinet. If air conditioning equipment is installed, use thermo-

stat wiring to connect the Y and C terminals on the furnace control

board to the yellow and brown wires on the condensing unit (unit out-

side). Refer to Figure 20.

IMPORTANT: Some electronic thermostats do not have adjustable heat

anticipators. They may have other type cycle rate adjustments. Follow

the thermostat manufacturer's instructions.

IMPORTANT: Set the heat anticipator in the room thermostat to 0.40

amps. Setting it lower will cause short cycles. Setting it higher will cause

the room temperature to exceed the set points.

The 24-volt, 40 VA transformer is sized for the furnace components

only, and should not be connected to power auxiliary devices such as

humidifiers, air cleaners, etc. The transformer may provide power for an

air conditioning unit contactor.

SECTION VI: ACCESSORY CONNECTIONS

The furnace control will allow power-switching control of various acces-

sories. Refer to Figure 21 for connection details.

ELECTRONIC AIR CLEANER CONNECTION

Two 1/4” (0.6 cm) spade terminals (EAC and EAC N) for electronic air

cleaner connections are located on the control board. The terminals

provide 115 VAC (1.0 amp maximum) during circulating blower opera-

tion.

HUMIDIFIER CONNECTION

Two 1/4” (0.6 cm) spade terminals (HUM and HUM N) for humidifier

connections are located on the control board. The terminals provide 115

VAC (1.0 amp maximum) during heating system operation.

SECTION VII: TWINNING AND STAGING

NOTE: You can twin two furnaces that have the same integrated control

module. Check the part number on the integrated control mod-

ule. You cannot twin

two furnaces that have different integrated

control module part numbers. If the part numbers of the two inte-

grated control modules are different they may not communicate

with each other so they will not work in a twinning application.

In applications where more heating capacity or more airflow capacity is

needed than what one furnace can deliver, twinning can be used to

make two furnaces operate in tandem. When two furnaces are installed

using the same duct system, it is very important that the two furnace cir-

culating air blowers operate in unison. If one blower starts before the

second blower, the duct system will become pressurized and the blower

on the second furnace will turn backwards causing the second furnace

to overheat, resulting in damage to the furnace. Twinning is used to

make two furnaces operate in tandem, using one duct system, one

room thermostat and causing both furnaces to turn on and off simulta-

neously.

FIGURE 18: Electrical Wiring - Upflow Position

FIGURE 19: Line Wiring Connections

BLK

WHT

GRN

BLK (HOT)

WHT (NEUTRAL)

GRN

NOMINAL

120 VOLT

ROOM

THERMOSTAT

FURNACE

CONTROL

CONDENSING

UNIT

TO AIR CONDITIONER

CONTROLS

COMMON T’STAT CONNECTION

FIGURE 20: Two-Stage Heating and Cooling Thermostat Connections

FIGURE 21: Accessory Connections

Room

Thermostat

Furnace

Control

Condensing

Unit

To Air Conditioner

Controls

Common T’stat Connection

115 VOLT

HUMIDIFIER

115 VOLT

ELECTRONIC

AIR CLEANER

BLK

WHT

EAC HOT

HUM. HOT

BLK

WHT

EAC

HUM

EAC

HUM

NEUTRALS

SWITCHED

CIRCUITS