ST9120U
Universal Electronic Fan Timers
INSTALLATION INSTRUCTIONS
APPLICATION
The ST9120U Universal Electronic Fan Timers integrate
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
ST9120U are to monitor the thermostat for heat, cool and
fan demands, run the induced draft blower motor and run
a circulating fan (up to two speeds) as required. The
electronic fan timers also monitor limit switch strings and
energize separate ignition control systems through spst
pressure switches. The ST9120U can replace any
ST9101 or ST9120 listed in Table 2 below. The electronic
fan timers feature a field-adjustable heat fan-on delay, a
field-adjustable heat fan-off delay, a field-adjustable cool
fan-on delay and a fixed cool fan-off delay.
Electronic air cleaner (EAC) and humidifier (HUM)
convenience terminal connections are provided as an
option. Continuous low speed indoor air circulation is
also provided.
SPECIFICATIONS
Electrical Ratings:
Power Voltage Requirements: 18 to 30 Vac, 60 Hz.
Contact Ratings:
Combustion Blower:
1.5A full load, 10A locked rotor at 115 Vac.
0.75A full load, 5A locked rotor at 230 Vac.
(Reduce full load rating by humidifier [HUM] 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 [EAC]
load.)
Continuous speed (optional):
8A full load, 16A locked rotor at 115 Vac.
4A full load, 8A locked rotor at 230 Vac.
EAC and HUM: 0.8A maximum combined load at 115
Vac.
Thermostat Load: 0.10A plus ignition system load.
On/Off Delay Settings:
Heat Speed:
Delay On: Field-adjustable, 30 or 60 seconds. Delay
timing starts when gas valve is energized.
Delay Off: Field-adjustable, 60, 100, 140 or 180 seconds. Delay timing starts when gas valve is deenergized.
Cool Speed:
Delay On: Field Adjustable, 4 or 30 seconds.
Delay Off: Fixed, 30 seconds.
Timing Tolerance: Larger of ±5% or ±2 seconds.
Post Purge Timing:
5 seconds.
Environmental Ratings:
Temperature: -40°F (-40°C) to +175°F (+79°C).
Humidity: 5 to 95 percent, noncondensing.
Approvals:
Underwriters Laboratories Inc. File No.: MP466.
Canadian Standards Association File No.: LR95329.
INSTALLATION
When Installing this Product...
1.
2.
3.
4.
Read these instructions carefully. Failure to follow
them could damage the product or cause a
hazardous condition.
Check the ratings and specifications given in the
instructions and on the product to make sure the
product is suitable for your application.
Installer must be a trained, experienced service
technician.
After installation is complete, check out the product
operation as provided in these instructions.
WARNING
Electrical Shock Hazard.
Can cause severe injury, death or property
damage.
Disconnect power supply before wiring to prevent
electrical shock or equipment damage. More than
one disconnection can be required.
®
69-0644-1
ST9120U UNIVERSAL ELECTRONIC FAN TIMERS
Location and Mounting
board. Be careful to directly connect to the new terminal or label each wire prior to removal from original board.
Mount the ST9120U Electronic Fan Timer in the appliance
wiring compartment using the four provided No. 6 selftapping screws.
Table 1. ST9101 to ST9120U Wiring Conversions
Wiring
Make sure that all wiring complies with local codes and
ordinances. Disconnect power before making wiring
connections. Refer to Figs. 1, 2, 3 and 4 for standard
wiring connections. Refer to Figs. 5 and 6 for internal
schematics. Refer to Fig. 7 for schematic of provided
ST9101 wiring adapter.
Setting Adjustable Heat Fan DIP Switches
Set the heat fan-on delay and cool fan-on delay DIP
switches as shown in Fig. 8. The heat-on delay time starts
when the main gas valve is energized at the start of a
thermostat call for heat; the heat-off delay time starts
when the main gas valve is de-energized at the end of a
thermostat call for heat. The cool fan-on delay time starts
when the compressor is energized at the start of a
thermostat call for cool.
ST9120 to ST9120U Wiring Conversion
Instructions
1.
2.
Turn off power to appliance. Carefully remove each
wire and connect directly to the corresponding location on the new ST9120U control board. Be careful
to directly connect to the new terminal with the
same labeled identity or label each wire prior to
removing from the original board. If original thermostat connection was a quick connect, cut off quick
connect, strip wire and insert into terminal block.
Identify the model number of the board being
replaced and set the dip switches based on Table 2.
ST9101 to ST9120U Wiring Conversion
Instructions
1.
Turn off power to appliance and carefully remove
each wire and connect directly to the new ST9120U
control board before removing the existing control.
Use Table 1 to determine the proper ST9120U terminal for each corresponding ST9101 connection.
Terminal
Terminal
ST9101
ST9120U
heat
heat
cool
cool
S
S
M1
Unused Motor Leads
M2
Unused Motor Leads
N
Neutral 1
N
Neutral 2
ACC
* for systems with one on fan
speed (see note below)
X
X sec
C
C xfmr
thermostat terminals
R
R
Y
Y
C
C
W
W
G
G
* ACC terminal is used in ST9101 systems, which use the
same fan speed for both heating and cooling. In order to
use the ST9120 to replace ST9101 devices in this type
of system, the fan connection that originally was connected to ACC on the ST9101 needs to be connected to
both heat and cool connections on the ST9120U.
2. Unplug the 9-pin connector and plug existing wiring
harness directly into the 9-pin connector found on
the ST9101 wiring adapter.
3. Plug the 6-pin connector found on the ST9101 wiring adapter directly to the open 6-pin connector on
the new ST9120U control board.
4. Take the two remaining white wires on the ST9101
wiring adapter and connect to Neutral quick connect
terminals 3 and 4 on the ST9120U
5. Take the black wire on the ST9101 wiring adapter
and connect to the S1 quick connect terminal on the
ST9120U
6. Take the blue wire on the ST9101 wiring adapter
and connect to the D1 quick connect terminal on the
ST9120U
7. Identify the model number of the board being
replaced and set the dip switches based on Table 2.
69-0644—1
2
ST9120U UNIVERSAL ELECTRONIC FAN TIMERS
Table 2. Recommended Default Dip Switch Settings
Model Number
Original OEM
Appliance
1
2
3
4
ST9101A1006
Rheem
off
on
off
on
ST9101A1014
Rheem
off
on
off
on
ST9101A1022
Trade
off
on
off
on
ST9120A1006
Armstrong
off
on
off
on
ST9120A2004
Armstrong
off
off
on
off
ST9120B1005
Ducane
off
off
off
on
ST9120C1012
Snyder General
off
on
off
off
ST9120C1020
Nordyne
off
on
off
off
ST9120C2002
York
off
on
off
on
ST9120C2010
Ducane
off
on
off
on
ST9120C2028
Armstrong
off
on
off
on
ST9120C3000
ICP
on
off
on
on
ST9120C3018
Bard
off
on
off
off
ST9120C4008
ICP
on
off
on
on
ST9120C4016
ICP
on
off
on
on
ST9120C4040
ICP
on
off
on
on
ST9120C4057
ICP
on
off
on
on
*ST9120C5005
ICP
off
off
on
on
*ST9120C5013
ICP
off
off
on
on
*ST9120D3009
Goodman
off
off
on
on
ST9120G2008
ICP
on
on
off
off
ST9120G2016
ICP
on
on
off
on
ST9120G2024
Skymark
on
off
off
on
ST9120G2032
Skymark
off
off
off
on
ST9120G4004
ICP
on
off
on
on
ST9120G4012
ICP
on
off
on
on
ST9120G4038
Trade
on
off
on
on
ST9120U1003
Trade
off
off
on
on
*ST9120U Factory Default Setting
*Heat fan off delay setting may need adjustment based on performance. See Figure 8 to adjust timings.
3
69-0644—1
ST9120U UNIVERSAL ELECTRONIC FAN TIMERS
L1 (H)
FUSE
L2 (N)
TO 115/230 VAC
POWER SUPPLY
115/230 VAC
HUMIDIFIER
TRANSFORMER
24 VAC
MV
LO
ML
MH
HI
4
NEUTRAL
N
N
CIR
2
C
X
S8600 INTERMITTENT
PILOT IGNITION MODULE
GND
24V
GND 24V
SPARK
MV/PV PV (BURNER)
LIMIT
CONTROL
SEC
3
XFMR
2
VR8204
COMBINATION
GAS CONTROL
X
ROLL-OUT
SWITCH
BLWR
HEAT
EAC
1
N
CONT
COOL
HUM
1
2
LEADS
DI
MOTOR
3
UNUSED
INDUCER MOTOR
STARTING
CAP
MV MV/PV PV
3
AIR CLEANER
1
CIRCULATING
FAN
Z1
PRESSURE
SWITCH
ST9120
Z2
THERMOSTAT
4
W
Y
G
R
DELAY
1
2
OFF
SPEED
UP
C
Y
C
G
COOLING
CONTACTOR
Y
W
R
PILOT
BURNER
1
CONNECT ONLY IF CONTINUOUS SPEED IS AVAILABLE AND USED.
2
CONNECT ONLY IF CONTINUOUS SPEED IS NOT USED.
3
CONNECT IF EAC AND HUM TERMINALS ARE AVAILABLE AND USED.
4
SOME MODELS USE MALE 1/4-INCH QUICK-CONNECTS INSTEAD OF SCREW TERMINALS FOR THERMOSTAT CONNECTIONS.
NOTE:
= DENOTES STANDARD TERMINAL.
DENOTES LINE VOLTAGE WIRING.
= DENOTES OPTIONAL TERMINAL.
DENOTES LOW VOLTAGE WIRING.
PILOT
BURNER
GROUND
Fig. 1. Typical ST9120U wiring connections with S8600 Intermittent Pilot Ignition Module.
69-0644—1
4
M5605A
ST9120U UNIVERSAL ELECTRONIC FAN TIMERS
HUMIDIFIER
FUSE
L1(H)
L2(N)
TO 115/230 VAC
POWER SUPPLY
3
AIR CLEANER
115/230 VAC
TRANSFORMER
ROLL-OUT
SWITCH
24 VAC
INDUCER MOTOR
LIMIT
CONTROL
HUM
2
EAC
N
CIR
2
X
X
SEC
C
XFMR
LEADS
4
NEUTRAL
N
LO
ML
MH
HI
BLWR
1
CIRCULATING
FAN
Z1
Y
G
PRESSURE
SWITCH
ST9120
Z2
4
THERMOSTAT
W
3
HEAT
1
2
1
N
CONT
COOL
STARTING
CAP
DI
MOTOR
3
UNUSED
SV9500 SMARTVALVE™
SYSTEM CONTROL
DELAY
R
1
2
OFF
SPEED
UP
C
Y
C
G
COOLING
CONTACTOR
Y
W
R
24 VOLT
COMMON
24 VOLT
HOT
EFT
OUTPUT
1
CONNECT ONLY IF CONTINUOUS SPEED IS AVAILABLE AND USED.
2
CONNECT ONLY IF CONTINUOUS SPEED IS NOT USED.
3
CONNECT IF EAC AND HUM TERMINALS ARE AVAILABLE AND USED.
4
SOME MODELS USE MALE 1/4-INCH QUICK-CONNECTS INSTEAD OF SCREW TERMINALS FOR THERMOSTAT CONNECTIONS.
NOTE:
= DENOTES STANDARD TERMINAL.
= DENOTES OPTIONAL TERMINAL.
24 VOLT
THERMOSTAT
OR PRESSURE
SWITCH
DENOTES LOW VOLTAGE WIRING.
DENOTES LINE VOLTAGE WIRING.
M5603A
Fig. 2. Typical ST9120U wiring connections with SV9500/SV9501 SmartValve™ System Control.
5
69-0644—1
ST9120U UNIVERSAL ELECTRONIC FAN TIMERS
THERMOSTAT
W
Y
R
G
W
G
Y
C
R
AUX
VENT
MV
MV
ROLLOUT
PRESSURE
SWITCH
STARTER
CAP
GAS VALVE
LO
HL
HH
HI
MAIN
LIMIT
X
S
A
C
C
H
E
A
T
C
O
O
L
CIRCULATING
FAN
C
N
M1 M2
CW23
24
VAC
120
VAC
TRANSFORMER
COMBUSTION
AIR BLOWER
N
TO 120 VAC
POWER SUPPLY
M2547A
L
INTERLOCK
Fig. 3. Typical ST9101 wiring connection in standing pilot system.
69-0644—1
6
ST9120U UNIVERSAL ELECTRONIC FAN TIMERS
COMBUSTION
AIR BLOWER
WIRE HARNESS ADAPTER
AUX
P1
L2 WHITE
L2 WHITE
2
PS/MV
DRIVE ORANGE
3
LIMIT RED
4
LIMIT RED
5
L1 BLACK
6
24V GND YELLOW
7
MV SENSE VIOLET
8
1
VENT
MV
MV
GAS VALVE
PRESSURE
SWITCH
ROLLOUT
3
6
1
4 NC
2
5
9
INDUCER BLUE
MAIN
LIMIT
120
VAC
N
TO 120 VAC
POWER SUPPLY
24
VAC
TRANSFORMER
2
4
N
NEUTRAL
N
N
CIR
2
C
SEC
XFMR
3
X
X
BLWR
HEAT
1
EAC
1
CONT
COOL
DI
HUM
LEADS
3
MOTOR
INTERLOCK
UNUSED
L
STARTER
CAP
1
LO
HL
HH
HI
Z1
ST9120
Z2
CIRCULATING
FAN
4
DELAY
1
2
OFF
SPEED
UP
C
Y
C
G
Y
R
W
CW23
THERMOSTAT
W
Y
G
R
M24001
Fig. 4. Typical ST9120U wiring connections with wire adapter for replacing ST9101.
7
69-0644—1
ST9120U UNIVERSAL ELECTRONIC FAN TIMERS
L1
(H)
L2
(N)
TO 115/230 VAC
POWER SUPPLY
FUSE
1
S1
INTERLOCK
S3
N/C
1
N1
EAC (N)
EAC (S)
ELECTRONIC AIR CLEANER
N1
1
K1
CONSTANT
LOW
2 M2
K1
K2
HEAT
K2
COOL
MED-LOW
CIRCULATION
BLOWER
MED-HIGH
M1
N2
HIGH
1
HUM (S)
HUM (N)
HUMIDIFIER
DI
K3
N3
INDUCER
MOTOR
N4
115/230 VAC
S2
TRANSFORMER
1
CN1
X
C
24 VAC
X-OT
X
LIMIT
CONTROL
1
C
1
Y
ST9120
ELECTRONIC
FAN TIMER
ROLL-OUT
SWITCH
6
3
R-OT
C
THERMOSTAT
G
PS1
Y
W
PRESSURE
SWITCH
R
FT
C
5
2
INTERMITTENT PILOT
COMBINATION
GAS CONTROL
MV
SPARK
TSTAT
1
2
MV/PV
PV
S8600
INTERMITTENT PILOT
IGNITION MODULE
24V
(GND)
DENOTES OPTIONAL CONNECTIONS, COMPONENTS AND ACCESSORIES.
CIRCULATION BLOWER LOW SPEED TAP CONNECTED TO OPTIONAL CONTINUOUS FAN SPEED TERMINAL IS SHOWN.
CONNECT CIRCULATION BLOWER LOW SPEED TAP TO M2 IF CONTINUOUS FAN OPTION NOT PROVIDED.
NOTE: DOTTED LINES REPRESENT PRINTED CIRCUIT BOARD WIRING.
Fig. 5. ST9120U internal schematic for Intermittent Pilot application.
69-0644—1
COOLING
CONTACTOR
8
M5606
ST9120U UNIVERSAL ELECTRONIC FAN TIMERS
FUSE
L1
(H)
TO 115/230 VAC
POWER SUPPLY
1
S1
S3
L2
(N)
INTERLOCK
EAC (N)
EAC (S)
K1
ELECTRONIC AIR CLEANER
CONSTANT
2
K1
N1
1
N/C
K2
HEAT
K2
COOL
MED-LOW
MED-HIGH
M1
CIRCULATING
FAN
HIGH
HUM (S)
K3
LOW
M2
1
HUM (N)
HUMIDIFIER
DI
N2
N3
INDUCER
MOTOR
N4
S2
115/230 VAC
TRANSFORMER
CN1
X
1
C
24 VAC
X-OT
X
LIMIT
CONTROL
C
1
1
Y
ST9120
ELECTRONIC
FAN TIMER
ROLL-OUT
SWITCH
6
3
R-OT
THERMOSTAT
C
G
PS1
Y
W
PRESSURE
SWITCH
R
4
FT
C
5
2
COOLING
CONTACTOR
SV9500 SMARTVALVE™
SYSTEM CONTROL
24V
1
2
TSTAT
FT
GND
DENOTES OPTIONAL CONNECTIONS, COMPONENTS AND ACCESSORIES.
CIRCULATION BLOWER LOW SPEED TAP CONNECTED TO OPTIONAL CONTINUOUS FAN SPEED TERMINAL IS SHOWN.
CONNECT CIRCULATION LOW SPEED TAP TO M2 IF CONTINUOUS FAN SPEED OPTION IS NOT PROVIDED.
NOTE: DOTTED LINES REPRESENT PRINTED CIRCUIT BOARD WIRING.
M5604
Fig. 6. ST9120U internal schematic for SmartValve™ System applications.
9
69-0644—1
ST9120U UNIVERSAL ELECTRONIC FAN TIMERS
Table 3. ST9101 Wire Adapter Connections
Color
Function
6pin
Connector
Pin Number
9pin
Connector
Pin Number
White
L2 Neutral
QC
1
White
L2 Neutral
QC
2
Orange
pressure switch to main valve
3
3
Red
limit
6
4
Red
limit
1
5
-
open
4
-
Black
L1 Hot
QC
6
Yellow
24V ground
2
7
Violet
main valve sense
5
8
Blue
inducer
QC
9
P1
1
2
L2 WHITE
L2 WHITE
3 PS/MV DRIVE ORANGE
LIMIT RED
4
LIMIT RED
5
L1 BLACK
6
24V GND YELLOW
7
MV SENSE VIOLET
8
3
8
1
4 NC
2
5
9
INDUCER BLUE
7
8
9
6
4
5
6
5
2
1
2
3
4
3
1
M23117
Fig. 7. ST9101 Wire Adapter Schematic
69-0644—1
10
ST9120U UNIVERSAL ELECTRONIC FAN TIMERS
CHECKOUT
C
N
N
CIR
X
X
Operate the system through at least one complete
heating cycle and cooling cycle to make sure the system
operates properly. Troubleshoot by checking for
appropriate voltages at the ST9120U terminals controlling
the combustion blower and heat and cool speed
circulating fan. The ST9120U schematics show internal
switching to clarify operation and assist in
troubleshooting. See Figs. 5 and 6.
SEC
4
XFMR
LEADS
EAC
3
2
NEUTRAL
BLWR
HEAT
HUM
2
1
N
CONT
COOL
1
DI
MOTOR
3
UNUSED
ST9120
Z1
Z2
DELAY
UP
OFF
G
C
SPEED
1 2 3 4
C
Y
R
W
Y
DELAY ON DIP SWITCH (4)
DELAY OFF DIP SWITCHES (2 & 3)
COOL DELAY ON DIP SWITCH (1)
COOL ON DELAY
1
1
4
SECONDS
30
SECONDS
HEAT ON DELAY
1
2
3
4
4
60
SECONDS
30
SECONDS
HEAT OFF DELAY
2
3
2
3
2
3
2
3
140
60
100
180
SECONDS SECONDS SECONDS SECONDS
FAN DELAY ON/OFF DIP SWITCH SETTINGS
M11990
Fig. 8. Setting heat fan-on, heat fan-off and cool fanon delay DIP switches.
Table 4. ST9120U Operating Sequence.
Action
System Response
Thermostat calls for heat.
(Terminal W is energized.)
1.
2.
3.
4.
5.
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 fan is energized at heat speed.
Thermostat ends call for heat.
(Terminal W is de-energized.)
1.
2.
3.
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.
(Terminals G and Y are energized.)
1.
2.
Cooling contactor is energized.
Circulating fan is energized at cool speed after cool fan-on delay
timing.
Thermostat ends call for cool.
(Terminals G and Y are de-energized.)
1.
2.
Cooling contactor is de-energized.
Circulating fan is de-energized after cool fan-off delay timing.
Thermostat begins call for fan.
(Terminal G is energized.)
1.
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.
2.
3.
NOTE: Circulating fan can be switched off for several seconds during
the transition between fan speeds.
Thermostat ends call for fan.
(Terminal G is de-energized.)
Circulating fan is de-energized.
11
69-0644—1
ST9120U UNIVERSAL ELECTRONIC FAN TIMERS
Action
System Response
Limit switch string opens.
1.
2.
Limit switch string remakes.
1.
2.
3.
Continuous circulating fan is connected.
(Optional connection to circulating fan low
speed tap.)
1.
Electronic air cleaner is connected.
(Optional connection to 120 Vac electronic
air cleaner.)
1.
2.
2.
Thermostat and ignition system are de-energized and gas valve
closes.
Combustion air blower and circulating fan heat speed are energized.
Combustion air blower remains energized for postpurge timing.
The circulating fan remains energized for the selected delay-off
timing.
Normal operation resumes.
Circulating fan low speed is energized when there is no call for
heat, cool, or fan.
If fan operation is required by a call for heat, cool, or fan, ST9120U
switches circulating fan to appropriate speed.
In two-speed systems, the electronic air cleaner is energized when
the heat or cool speed of the circulating fan is energized.
If continuous fan option is used, connect EAC to line voltage input
S1. Line voltage hot lead is also connected in input S1.
Humidity control is connected.
Humidifier is energized when combustion air blower is energized.
(Optional connection to 120 Vac humidifier.)
Automation and Control Solutions
Honeywell International Inc.
Honeywell Limited-Honeywell Limitée
1985 Douglas Drive North
35 Dynamic Drive
Golden Valley, MN 55422
Scarborough, Ontario M1V 4Z9
customer.honeywell.com
® U.S. Registered Trademark
© 2005 Honeywell International Inc.
69-0644—1 M.S. Rev. 11-05