ST9141A1002 Electronic Fan T imer
Application
The ST9141A1002 Electronic Fan Timer integrates control of all combustion blower and circulating fan operations
in a gas warm air appliance. This control is the central
wiring point for most of the electrical components in the
furnace. The basic purposes of the ST9141A1002 are to
monitor the thermostat for heat, cool, and fan demands and
run the induced draft blower motor and up to a two-speed
circulating fan as required. The ST9141A1002 monitors an
spdt pressure switch, burner limit and primary limit. A
Honeywell SV9500 Hot Surface Pilot Ignition System
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.
NOTE: Use this control to replace an identical ST9141A1002
Electronic Fan Timer only. This control is not for use in
general applications.
Specifications
ELECTRICAL RATINGS:
Power Requirements:
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:
Delay On: 30 seconds, fixed.
Delay Off: 60, 100, 140 or 180 seconds, field
adjustable.
Cool Speed:
Delay On: 6 seconds, fixed.
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.
LIGHT-EMITTING DIODE (LED) INDICATIONS:
LED flashing dim-bright indicates normal operation.
LED off when control is powered indicates defective
control.
LED on continuously when control is powered indicates
defective control.
LED flashing in a cycle with LED on followed by one
or more off pulses indicates the following system
errors.
Number
of Off
Flash
Pulses System Condition
1 Burner limit circuit is open.
2 Primary limit circuit is open.
3 Pressure switch circuit is improp-
4 Control is in lockout due to air
erly closed.
not circulating (overheating).
Installation
WHEN INSTALLING THIS PRODUCT…
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a hazardous condition.
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.
CA UTION
!
Disconnect power supply before wiring to prevent electrical shock or equipment damage.
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.
Wiring
All wiring must comply with local codes and ordinances. Disconnect power before making wiring connections. Refer to Fig. 1 for standard wiring connections. Refer
to Fig. 2 for an internal schematic.
1 69-0780
C.H. • 6-93 • ©Honeywell Inc. 1993 • Form Number 69-0780
Fig. 1—Typical ST9141A1002 wiring connections.
HUMIDIFIER
AIR CLEANER
COMBUSTION
BLOWER
STARTING
CAP
LO
ML
MH
HI
CIRCULATING
FAN
THERMOSTAT
NOTE:
3 DI
HUM N
12
Z1
Z2
DELAY
1
GRW
Y
2
OFF
= DENOTES STANDARD TERMINAL.
= DENOTES TERMINAL NOT PROVIDED.
DENOTES LINE VOLTAGE CONNECTIONS.
DENOTES LOW VOLTAGE CONNECTIONS.
UNUSED
EAC N
SPEED
UP
MOTOR
CY
N
LEADS
123
ST9141
NEUTRAL
CIR
C
CONT
COOL
G
4
BLWR
HEAT
FUSE
Y
XFMR
CX
W
120 VAC
TRANSFORMER
24 VAC
SEC
X
R
L1 (H)
TO 120 VAC
POWER SUPPLY
L2 (N)
PRIMARY
LIMIT
COOLING
CONTACTOR
N.C.
BURNER
LIMIT
PRESSURE
SWITCH
SV9500
HOT SURFACE
PILOT IGNITION
SYSTEM CONTROL
N.O.
24 VOLT
COMMON
24 VOLT
THERMOSTAT
OR PRESSURE
SWITCH
24 VOLT
HOT
EFT
OUTPUT
M5607
2
Fig. 2—ST9141A1002 internal schematic.
L1-1
N.O.
K1
BURNER
LIMIT
PRIMARY
LIMIT
COM.
PRESSURE
SWITCH
N.C.
L1-2
CN1
1
6
8
3
7
EAC (S)
K2 HEAT
K2
R-OT
PS1
PS2
COOL
K3A
X-OT
FUSE
HUM (S)
DI
L1
(H)
TO 120 VAC
POWER SUPPLY
INTERLOCK
ELECTRONIC AIR CLEANER
M2
M1
HUMIDIFIER
X
K3B
MED-LOW
MED-HIGH
COMBUSTION
AIR BLOWER
120 VAC
24 VAC
ST9141A
ELECTRONIC
FAN TIMER
FT
5
L2
(N)
LOW
HIGH
TRANSFORMER
24V
4
CIRCULATING
FAN
C
G
Y
W
R
C
2
EAC (N)
HUM (N)
N3
N4
N2
C
THERMOSTAT
N1
COOLING
CONTACTOR
NOTE: DOTTED LINES REPRESENT PRINTED CIRCUIT BOARD WIRING.
3 69-0780
SV9500 HOT SURFACE PILOT
IGNITION SYSTEM CONTROL
24V
TSTAT FT
GND
M5608
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.
Checkout
Fig. 3—Setting delay off DIP switches.
ST9141
12
3 DI
HUM N
UNUSED
EAC N
MOTOR
N
LEADS
123
NEUTRAL
CIR
CONT
COOL
4
BLWR
CX
HEAT
XFMR
SEC
X
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
Z1
Z2
fan. The ST9141A1002 schematic shows internal switching to clarify operation and assist in troubleshooting. See
Fig. 2.
DELAY
SPEED
1
2
UP
1
CY
2
C
140 SECONDS
OFF
1
2
60 SECONDS 100 SECONDS
DELAY OFF DIP SWITCH SETTINGS
G
1
2
Y
W
180 SECONDS
R
ON
OFF
1
2
M5658
ST9141A1002 Operating Sequence
Action System Response
Thermostat calls for heat. • Pressure switch confirmed in no airflow position. (If pressure switch shows
(W terminal is energized.) 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. • Ignition system is de-energized and gas valve closes.
(W terminal is de-energized.) • 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. • Cooling contactor is energized.
(G and Y terminals are energized.) • Circulating fan is energized at cool speed after cool fan on delay timing.
Thermostat ends call for cool. • Cooling contactor is de-energized.
(G and Y terminals are de-energized.) • Circulating fan turns off after cool fan off delay timing.
Thermostat begins call for fan. • Circulating fan is energized at heat speed two seconds after G terminal is
(G terminal is energized.) 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 foursecond delay.
Thermostat ends call for fan. • Circulating fan is de-energized.
(G terminal 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
ST9141A1002 Operating Sequence (Continued)
Action System Response
Primary limit switch string closes. • Circulating fan turns off after the selected heat fan off delay timing.
Primary limit switch string is open • Combustion air blower, circulating fan and ignition system are de-energized.
for more than 150 seconds (on each • Control goes into lockout mode.
of three consecutive cycles). • LED flashes four times.
Burner limit opens. • Thermostat and ignition system are de-energized and gas valve closes.
Burner limit closes. • Combustion air blower remains energized for postpurge timing.
Electronic air cleaner is connected. • Electronic air cleaner is energized when the circulating fan heat or cool speed
(Connector to 120 Vac electronic is energized.
air cleaner.)
Humidity control is connected. • Humidifier is energized when combustion air blower is energized.
(Connector to 120 Vac humidifier.)
• LED stops flashing.
• Normal operation resumes.
• Control remains in lockout until 24V power is removed and reapplied (control
is reset).
• LED stops flashing.
• Normal operation resumes.
• Combustion air blower and circulating fan heat speed are energized.
• LED flashes once.
• The circulating fan remains energized for the selected delay off timing.
• LED stops flashing.
• Normal operation resumes.
5 69-0780
Home and Building Control Home and Building Control Helping You Control Your World
Honeywell Inc. Honeywell Limited—Honeywell Limitée
1985 Douglas Drive North 740 Ellesmere Road
Golden Valley, MN 55422 Scarborough, Ontario
Printed in U.S.A.
M1P 2V9
6
QUALITY IS KEY
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