9
TWINNING AND/OR
COMPONENT TEST
TERMINAL
PL1 − LOW VOLTAGE MAIN
HARNESS CONNECTOR
TRANSFORMER 24VAC
CONNECTIONS
EAC TERMINAL
(115 VAC 1.0 AMP MAX.)
SEC-2
115−VAC (L2)
NEUTRAL
CONNECTIONS
24−V THERMOSTAT
TERMINALS
HUMIDIFIER TERMINAL
(24−VAC 0.5 AMP MAX)
3−AMP FUSE
LED
OPERATION &
DIAGNOSTIC
LIGHT
SEC-1
BLOWER SPEED
SELECTION TERMINALS
BL−1
PR-1
COM
HEAT
COOL
FAN
SPARE2
SPARE1
Y1
DHUM
BLOWER OFF-DELAY
120
1
8
0
90 150
24V MTR T
A
PS
115 VAC (L1)
INPUT
L1
IND
PL-2 HOT SURFACE
IGNITOR (HSI) &
INDUCER MOTOR
(IND) CONNECTOR
HUM
EAC-1
HSI
PL-2
PL1
EAC-2
Com
24V
L2
A11391
Fig. 14 -- Single--Stage Furnace Control
Burner Flame
Burner
Manifold
A11461
Fig. 15 -- Burner Flame
CHECK LOW GAS PRESSURE SWITCH
The newly installed low gas pressure switch is a safety device
used to guard against adverse burner operating characteristics that
can result from low gas supply pressure. Switch opens at not less
than 7.2 in. W.C. and closes at not greater than 10.2 in. W.C.
This switch also prevents operation when the propane tank level
is low which can result in gas with a high concentration of
impurities, additives, and residues that have settled to the bottom
of the tank. Operation under these conditions can cause harm to
the heat exchanger system. This normally open switch closes
when gas is supplied to gas valve under normal operating
pressure.
The closed switch completes control circuit. Should an
interruption or reduction in gas supply occur, the gas pressure at
switch drops below low gas pressure switch setting, and switch
opens. Any interruption in control circuit (in which low gas
pressure switch is wired) quickly closes gas valve and stops gas
flow to burners. When normal gas pressure is restored, the system
must be electrically reset to re--establish normal heating operation.
Before leaving installation, observe unit operation through 2
complete heating cycles. During this time, turn gas supply to gas
valve off just long enough to completely extinguish burner flame,
then instantly restore full gas supply. To ensure proper low gas
pressure switch operation, observe that there is no gas supply to
burners until after hot surface igniter begins glowing.
LABEL APPLICATION
1. Fill in Conversion Responsibility Label 339852--205 (see
Fig. 32) and apply to blower door of furnace as shown.
Date, name, and address of organization making this con-
version are required.
2. Attach Conversion Rating Plate Label 339852--201 to out-
er door of furnace.
3. Apply Gas Control Conversion Label to gas valve: For
single--stage gas valve apply label 339852--202 to gas
valve. (Do not use 339852--203, which is similar) Check
for correct normal operating sequence of the ignition sys-
tem as described in furnace Installation, Start--Up, and Op-
erating Instructions.
4. Replace control access door, blower door and outer door
of furnace.
CHECKOUT
1. Observe unit operation through 2 complete heating cycles.
2. See Sequence of Operation in furnace Installation, Start--
Up, and Operating Instructions.
3. Set room thermostat to desired temperature.
