ST9141A1002 Electronic Fan Timer
LIGHT-EMITTING DIODE (LED) INDICATIONS:
Application
LED flashing dim-bright indicates normal operation.
LED off when control is powered indicates defective
The ST9141A1002 Electronic Fan Timer integrates con-
control.
trol of all combustion blower and circulating fan operations
LED on continuously when control is powered indicates
in a gas warm air appliance. This control is the central
defective control.
wiring point for most of the electrical components in the
LED flashing in a cycle with LED on followed by one
furnace. The basic purposes of the ST9141A1002 are to
or more off pulses indicates the following system
monitor the thermostat for heat, cool, and fan demands and
errors.
run the induced draft blower motor and up to a two-speed
circulating fan as required. The ST9141A1002 monitors an
Number
spdt pressure switch, burner limit and primary limit. A
of Off
Honeywell SV9500 Hot Surface Pilot Ignition System
Flash
Control manages the burner, which is energized through
the pressure switch. A light-emitting diode (LED) indicates
system status.
In addition, this model includes electronic air cleaner
and humidifier convenience terminal connections.
Pulses
System Condition
1
2
3
Burner limit circuit is open.
Primary limit circuit is open.
Pressure switch circuit is improp-
erly closed.
NOTE:UsethiscontroltoreplaceanidenticalST9141A1002
Electronic Fan Timer only. This control is not for use in
general applications.
4
Control is in lockout due to air
not circulating (overheating).
Specifications
Installation
ELECTRICAL RATINGS:
Power Requirements:
WHEN INSTALLING THIS PRODUCT…
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a hazardous condi-
tion.
2. Check the ratings and specifications given in the
instructions and on the product to ensure the product is
suitable for your application.
3. Installer must be a trained, experienced service
technician.
4. After installation is complete, check out the product
operation as provided in these instructions.
Voltage: 18-30 Vac, 60 Hz.
Contact Ratings:
Combustion Blower:
1.5A Full Load, 10A Locked Rotor at 115 Vac.
.75A Full Load, 5A Locked Rotor at 230 Vac.
Reduce full load rating by humidifier load.
Circulating Fan (Heat-Cool Speed):
15A Full Load, 30A Locked Rotor at 115 Vac.
7.5A Full Load, 15A Locked Rotor at 230 Vac.
Reduce full load rating by electronic air cleaner
load.
Thermostat Load: 0.06A plus ignition system current
draw.
ON/OFF DELAY SETTINGS:
Heat Speed:
CAUTION
!
Disconnect power supply before wiring to pre-
vent electrical shock or equipment damage.
Delay On: 30 seconds, fixed.
Delay Off: 60, 100, 140 or 180 seconds, field
adjustable.
Cool Speed:
Delay On: 6 seconds, fixed.
Location and Mounting
The ST9141A1002 is mounted in the appliance wiring
compartment using four No. 6 screws (obtained locally)
through holes on the corners of the enclosure.
Delay Off: 60 seconds, fixed.
Timing Tolerance: Larger of ±5% or ±2 seconds.
POSTPURGE TIMING: 5 seconds.
ENVIRONMENTAL RATINGS
Temperature: -40° to +175° F [-40° to +79° C].
Humidity: 5 to 95%, noncondensing.
Wiring
All wiring must comply with local codes and ordi-
nances. Disconnect power before making wiring connec-
tions. Refer to Fig. 1 for standard wiring connections. Refer
to Fig. 2 for an internal schematic.
C.H. • 6-93 • ©Honeywell Inc. 1993 • Form Number69-0780
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Fig. 2—ST9141A1002 internal schematic.
L1
L2
(H)
(N)
TO 120 VAC
FUSE
POWER SUPPLY
INTERLOCK
L1-1
N1
EAC (N)
EAC (S)
ELECTRONIC AIR CLEANER
LOW
M2
CIRCULATING
FAN
MED-LOW
MED-HIGH
HIGH
K1
K2
K2
HEAT
COOL
N2
M1
HUM (S)
HUM (N)
HUMIDIFIER
K3A
COMBUSTION
AIR BLOWER
DI
N3
N4
L1-2
120 VAC
TRANSFORMER
CN1
X
C
24 VAC
1
X-OT
BURNER
LIMIT
6
PRIMARY
LIMIT
ST9141A
ELECTRONIC
FAN TIMER
THERMOSTAT
C
R-OT
PS1
8
G
Y
3
N.C.
N.O.
W
R
K3B
COM.
7
PS2
FT
5
24V
4
PRESSURE
SWITCH
C
COOLING
CONTACTOR
2
SV9500 HOT SURFACE PILOT
IGNITION SYSTEM CONTROL
24V
GND
TSTAT
FT
NOTE: DOTTED LINES REPRESENT PRINTED CIRCUIT BOARD WIRING.
M5608
3
69-0780
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Setting the Heat Fan Off Delay DIP Switches
Set the heat fan off delay DIP switches to 60, 100, 140 or
180 seconds as shown in Fig. 3. The off delay is factory-set
at 140 seconds. This delay time starts when the main gas
valve is de-energized at the end of a thermostat call for heat.
Fig. 3—Setting delay off DIP switches.
ST9141
2
1
3
4
N
3
DI
C
X
X
NEUTRAL
CIR
BLWR
EAC
N
1
2
HUM
N
Checkout
Assure the system operates properly by operating the
system through at least one complete heating cycle and
cooling cycle. Troubleshoot by checking for appropriate
voltages at the ST9141A1002 terminals controlling the
combustion air blower and heat and cool speed circulating
fan. The ST9141A1002 schematic shows internal switch-
ing to clarify operation and assist in troubleshooting. See
Fig. 2.
Z1
Z2
DELAY
SPEED
1
2
UP
C
Y
OFF
G
C
R
Y
W
ON
OFF
1
2
1
2
1
2
1
2
180 SECONDS
60 SECONDS 100 SECONDS 140 SECONDS
DELAY OFF DIP SWITCH SETTINGS
M5658
ST9141A1002 Operating Sequence
Action
System Response
Thermostat calls for heat.
(W terminal is energized.)
•
Pressure switch confirmed in no airflow position. (If pressure switch shows
airflow, LED flashes three times.)
Combustion air blower is energized.
Air proving switch makes (air flow is established).
Ignition system is energized.
Gas valve opens and main burner lights.
•
•
•
•
•
Heat fan on delay timing begins. When timing is complete, circulating blower
is energized at heat speed.
Thermostat ends call for heat.
(W terminal is de-energized.)
•
•
•
Ignition system is de-energized and gas valve closes.
Combustion air blower is de-energized after postpurge timing.
Heat fan off delay timing begins. When timing is complete, the circulating fan
is de-energized.
Thermostat begins call for cool.
(G and Y terminals are energized.)
•
•
Cooling contactor is energized.
Circulating fan is energized at cool speed after cool fan on delay timing.
Thermostat ends call for cool.
(G and Y terminals are de-energized.)
•
•
Cooling contactor is de-energized.
Circulating fan turns off after cool fan off delay timing.
Thermostat begins call for fan.
(G terminal is energized.)
•
Circulating fan is energized at heat speed two seconds after G terminal is
energized.
If a call for heat occurs, circulating fan continues to run at heat speed.
If a call for cool occurs, circulating fan switches to cool speed after four-
second delay.
•
•
Thermostat ends call for fan.
(G terminal is de-energized.)
•
Circulating fan is de-energized.
Primary limit switch string opens.
•
•
•
•
•
Thermostat and ignition system are de-energized and gas valve closes.
Combustion air blower is de-energized.
Circulating fan is energized at heat speed.
LED flashes twice.
If there is a call for cooling or fan, the circulating fan switches from heat speed
to cool speed.
(continued)
4
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ST9141A1002 Operating Sequence (Continued)
Action
System Response
Primary limit switch string closes.
•
•
•
Circulating fan turns off after the selected heat fan off delay timing.
LED stops flashing.
Normal operation resumes.
Primary limit switch string is open
for more than 150 seconds (on each
of three consecutive cycles).
•
•
•
•
Combustion air blower, circulating fan and ignition system are de-energized.
Control goes into lockout mode.
LED flashes four times.
Control remains in lockout until 24V power is removed and reapplied (control
is reset).
•
•
LED stops flashing.
Normal operation resumes.
Burner limit opens.
Burner limit closes.
•
•
•
Thermostat and ignition system are de-energized and gas valve closes.
Combustion air blower and circulating fan heat speed are energized.
LED flashes once.
•
•
•
•
Combustion air blower remains energized for postpurge timing.
The circulating fan remains energized for the selected delay off timing.
LED stops flashing.
Normal operation resumes.
Electronic air cleaner is connected.
(Connector to 120 Vac electronic
air cleaner.)
•
Electronic air cleaner is energized when the circulating fan heat or cool speed
is energized.
Humidity control is connected.
•
Humidifier is energized when combustion air blower is energized.
(Connector to 120 Vac humidifier.)
5
69-0780
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Home and Building Control
Honeywell Inc.
1985 Douglas Drive North
Golden Valley, MN 55422
Home and Building Control
Honeywell Limited—Honeywell Limitée
740 Ellesmere Road
Helping You Control Your World
Scarborough, Ontario
M1P 2V9
QUALITY IS KEY
Printed in U.S.A.
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