SERVICING
36
RED
RESET
BUTTON
COLOR
IDENTIFYING
Checking Flame Rollout Switch
a. If no voltage is measured on either side of control it
indicates ignition control or wiring to control problem.
b. If voltage is measured on one side of the control and
not the other it indicates the control is open.
c. If voltage is measured on both sides of the control the
wiring to gas valve or valve is at fault.
3. After check and/or replacement of rollout switch, reinstall
burner compartment door and verify proper unit operation.
S-303 INDUCED DRAFT BLOWER MOTOR
WARNING
HIGH
VOLTAGE
D
I
S
CONNECT
ALL
POWE
R
BEFO
R
E
S
E
R
VICING
O
R
IN
S
TALLING
THI
S
UNIT.
M
ULTIPLE
POWE
R S
OU
R
CE
S
MAY
BE
P
R
E
S
ENT.
F
AILU
R
E
TO
DO
S
O
MAY
CAU
S
E
P
R
OPE
R
TY
DAMAGE,
PE
RS
ONAL
IN
J
U
R
Y
O
R
DEATH.
1. Remove burner compartment door to gain access to
the induced draft blower motor.
2. Disconnect the motor wire leads from its connection
point at the induced draft motor.
3. Using a ohmmeter, test for continuity between each of
the motor leads.
4. Touch one probe of the ohmmeter to the motor frame
(ground) and the other probe in turn to each lead.
If the windings do not test continuous or a reading is
obtained to ground, replace the motor.
5. If the windings have a continuity reading, reconnect
wires. Turn power on to the furnace and turn the
thermostat on in the heating mode. Check voltage for
115V at the induced draft motor terminals during the tri-
al for ignition. If you have 115V and the motor does not
run, replace the induced draft motor.
6. After completing check and/or replacement of induced
draft motor, reinstall burner compartment door.
7. Turn on electrical power and verify proper unit opera-
tion.
S-304 CHECKING GAS VALVE (Redundant)
A combination redundant operator type gas valve which
provides all manual and automatic control functions required
for gas fired heating equipment is used.
The valve provides control of main burner gas flow, pressure
regulation, and 100 percent safety shut-off.
WARNING
D
I
S
CONNECT
ALL
POWE
R
BEFO
R
E
S
E
R
VICING
Single stage gas valves should be tested on the furnance with
24 VAC connected to the gas valve and manometers reading
supply line and manifold pressures.
S-305 CHECKING MAIN BURNERS
The main burners are used to provide complete combustion
of various fuels in a limited space, and transfer this heat of
the burning process to the heat exchanger.
Proper ignition, combustion, and extinction are primarily due
to burner design, orifice sizing, gas pressure, primary and
secondary air, vent and proper seating of burners.
.023" - .027"
Beckett Burner
WARNING
D
I
S
CONNECT
ALL
G
A
S
AND
E
LECT
R
ICAL
P
OWE
R
S
UPPLY.
In checking main burners, look for signs of rust, oversized and
undersized carry over ports restricted with foreign material,
etc, refer to previous drawing. Burner cross-over slots must
not be altered in size.
S-306 CHECKING ORIFICES
A predetermined fixed gas orifice is used in all of these
furnaces. That is an orifice which has a fixed bore and position
as shown in the following drawing.
No resizing should be attempted until all factors are taken
into consideration such as inlet and manifold gas pressure,
alignment, and positioning, specific gravity and BTU content
of the gas being consumed.
The only time resizing is required is when a reduction in firing
rate is required for an increase in altitude.
