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installations, all electrical connections must be made in accordance
with Canadian Electrical Code CSA C22.1 or authorities having
jurisdiction.

24-v Wiring

Make field 24-v connections at the 24-v terminal strip. (See Fig. 9
and 10.) Connect terminal Y as shown for proper operation in
cooling mode. Use only AWG No. 18 color-coded wire.

The 24-v circuit contains an automotive-type, 3-amp fuse located
on the main control board. Any direct shorts during installation,
service, or maintenance could cause this fuse to blow. If fuse
replacement is required, use ONLY a 3-amp fuse of identical size.

Accessory

Electronic air cleaner (EAC)

Two screw terminals (EAC-1 and EAC-2) are provided for
EAC connection. The terminals are energized with 115-v,
1-amp maximum during blower motor operation.

VII.

VENTING

Refer to the enclosed Installation Instructions, GAMA Venting
Tables for Category I Furnaces and EZ VENT™ Tables for
Category I Fan-Assisted Furnaces. The horizontal portion of the
venting system shall maintain a minimum of 1/4-in. upward slope
per linear ft and it shall be rigidly supported every 5 ft or less with
hangers or straps to ensure that there will be no movement after
installation.

VIII.

START-UP, ADJUSTMENT, AND SAFETY CHECK

General

The furnace must have a 115-v power supply properly connected
and grounded. Thermostat wire connections at R,W,C, and Y must
be made at the 24-v terminal block on the control board. The gas
service pressure must not exceed 0.5 psig (14-in. wc), but must be
no less than 0.16 psig (4.5-in. wc).

Before operating the furnace, check each manual reset switch for
continuity. If necessary, press the button to reset the switch.

The blower compartment door must be in place to complete the
115-v circuit to the furnace.

CAUTION:

This furnace is equipped with a fuse link in

the gas control area. The switch will open and shut off
power to the gas valve if a flame rollout or an overheating
condition occurs in the gas control area. DO NOT bypass
the switch. Correct inadequate combustion air supply
problem and reset the switches.

Sequence of Operation

Using the schematic diagram shown in Fig. 11, follow the
sequence of operation through the different modes. (See Fig. 11.)

NOTE:

When the blower door is in place, 115v is supplied

through blower door switch ILK to heating fan relay HFR, and
transformer TRAN. Transformer TRAN energizes the safety
circuit containing auxiliary limit switch ALS, fuse link FL, and
limit switch LS to energize R.

With the furnace pilot lit, the thermocouple will energize the
thermal magnet circuit of gas valve GV, permitting gas flow to the
remaining portion of the gas valve.

1. Heating mode

a. When the wall thermostat "calls for heat," the R-W

circuit closes. This closed circuit supplies power to the
24-v safety circuit containing automatic reset limit
switch LS and fuse link FL.

b. The inducer motor relay coil IDR is energized. Inducer

motor relay contacts in the 115-v circuit close, starting
inducer motor IDM. Simultaneously, another set of
contacts in the inducer motor relay IDR closes in the
24-v circuit and locks in until the R-W circuit or safety
circuit opens.

c. As inducer motor IDM comes to speed, pressure switch

PRS actuates and supplies power through manual reset
draft safeguard switch DSS. This process energizes both
solenoid coils in gas valve GV, causes the valve to opens
which permits gas flow to the main burners where the
gas is ignited by the pilot.

d. Simultaneously, the solid-state time-delay circuit in the

blower control center is energized. Approximately 45
sec after the R-W circuit closes, heating fan relay coil
HFR is energized, closes the 115-v contacts of the
heating fan relay HFR and starts blower motor BLWM
on heating speed. EAC terminals energize with 115v
when blower operates in either heating or cooling speed.

e. When the thermostat is satisfied, the R-W circuit is

broken, de-energizing both solenoid coils of gas valve
GV and the solid-state time-delay circuit for the heating
fan relay HFR. Gas flow to the main burners immedi-
ately stops. Approximately 120 sec (or 180 sec depend-
ing on the blower off time selected) after main burners
are extinguished, heating fan relay HFR is de-energized
and blower motor BLWM stops. The blower off delay
can be permanently changed to 180 sec by cutting
resistor. (See Fig. 9.)

f. If the pilot flame is extinguished, the thermocouple no

longer energizes the thermal magnet circuit of gas valve
GV. Gas flow to the pilot and main burners stops until
the pilot is manually relit.

Fig. 9—Control Center

A91226

MAX. 1.0 AMPS
115-VAC

SEC-2

SEC-1

GROUND
SCREW
REQUIRED

3-AMP
FUSE

BLOWER
OFF-DELAY

24-VAC
COMMON

CES0110074-00