Honeywell ST9120U Installation Manual

ST9120B,U

Universal Electronic Fan Timers

INSTALLATION INSTRUCTIONS

APPLICATION	On/Off Delay Settings:

The ST9120B,U 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 ST9120B,U 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 ST9120B,U also monitors limit switch strings and energizes separate ignition control systems through pressure switches. The ST9120B,U can replace any ST9101, ST9120, ST9141 or ST9160 listed in Table 3 below. The ST9120B,U features a field-adjustable heat fan-on delay, a field-adjustable heat fan-off delay, a fieldadjustable cool fan-on delay and a field-adjustable cool fan-off delay.

Electronic air cleaner (EAC) and humidifier (HUM) convenience terminal connections and continuous low speed indoor air circulation are provided.

SPECIFICATIONS

Electrical Ratings:

Power Voltage Requirements: 18 to 30 VAC, 50/60 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

0.4A maximum combined load at 230 VAC Thermostat W Load: 100mA at 24 VAC, plus ignition sys-

tem load.

Thermostat G, Y, Primary Limit, Burner Limit, Pressure Switch Load: 22mA at 24 VAC load/cleaning current.

NOTE: Timing is derived from 24 VAC supply frequency and is valid for 60Hz. At 50 Hz, the timings are lengthened 20%.

Heat Speed:

Delay On: Field-adjustable, 30 or 60 seconds. Delay timing starts when gas valve is energized.

Delay Off: Field-adjustable, 60, 120, 150 or 180 seconds. Delay timing starts when gas valve is deenergized.

Cool Speed:

Delay On: Field Adjustable, 4 or 30 seconds. Delay Off: Field Adjustable, 30 or 60 seconds.

Timing Tolerance: Larger of ±2% 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.

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 make sure 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.

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.

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ST9120B,U UNIVERSAL ELECTRONIC FAN TIMERS

Location and Mounting

Mount the ST9120B,U Electronic Fan Timer in the appliance wiring compartment using the two # 8 1/2-in. self-tapping screws.

Wiring

CAUTION

Explosion or fire hazard.

When installing the ST9120B,U, carefully check all appliance wires to make sure they are all connected to desired terminals at ST9120B,U. Incorrect wiring can lead to explosion hazard, fire, or equipment damage.

Make sure that all wiring complies with local codes and ordinances. Disconnect power before making wiring connections. Refer to Fig. 1–6 for standard wiring connections. Refer to Fig. 7–9 for schematic of provided wiring adapters.

Adjustable DIP Switch

The ST9120B,U control provides a wide variety of configurable heat on, heat off, cool on and cool off delays. Set the delay DIP switches as shown in Fig. 10 The heaton 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 deenergized 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. The cool fan-off delay time starts when the compressor is deenergized at the end of thermostat call for cool.

Twinning

Twinning mode is used when two ST9120B,U controls operate in parallel. In this mode blower outputs (heat, cool and continuous speed) are activated or deactivated at both controls at the same time. Both ST9120B,U are synchronized through a communication bridge utilizing TWIN quick connect terminals, communication hardware and special software package.

To get into twinning mode both ST9120B,U must share common 24 VAC ground, both must be supplied off the same 24 VAC transformer or two identically-phased transformers and the TWIN terminals must be interconnected together. One or both ST9120B,U must be connected to the thermostat.

If two 24 VAC transformers are used (one for each ST9120B,U) then the transformers must be phased in (24 VAC HOT legs connected to X terminals at each ST9120B,U unit must be in the same phase relative to the 24 VAC common ground). If the transformers are phased out the twinning mode will not be achieved.

It is permissible to interconnect just two ST9120B,U to operate in the twinning mode. The ST9120B,U Twinning mode is not backwards compatible with legacy Electronic Fan Timers.

To operate in twinning mode:

1.Interconnect C quick connect terminals at both twinned ST9120B,U.

2.Interconnect TWIN quick connect terminals at both twinned ST9120B,U.

3.Use insulate wires of wire gauge at least AWG 24 for the interconnections. Wire lengths shall not exceed 5 m (15 ft.). Both C and TWIN wires shall lead in parallel to each other. Keep the wires out of wires under line voltage, ignition cable and other sources of electrical noise.

ST9120B,U Wiring Conversion

Instructions

1.Turn off power to appliance. Carefully remove each wire and connect directly to the corresponding location on the new ST9120B,U 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.

2.Identify the model number of the board being replaced and set the dip switches based on Table 3.

CAUTION

Explosion Hazard/Fire Hazard

ST9101 wiring harness adapter and ST9141 wiring harness adapter are very similar because both use identical connectors. Ensure proper harness is selected for the target system. Using the wrong wiring harness adapter leads to target system and/or ST9120B,U control damage.

ST9101 to ST9120B,U Wiring Conversion Instructions

1.Turn off power to appliance and carefully remove each wire and connect directly to the new ST9120B,U control board before removing the existing control. Use Table 1 to determine the proper ST9120B,U terminal for each corresponding ST9101 connection. Connect the wiring in accordance with schematic at Fig. 3. Be careful to directly connect to the new terminal or label each wire prior to removal from original board.

CAUTION

Electronic air cleaner use.

If electronic air cleaner is used in systems with continuous blower speed, connect the electronic air cleaner to line voltage input L1.

2.Unplug the 9-pin connector and plug existing wiring harness directly into the 9-pin connector found on the ST9101 wiring adapter 50011959. See Fig. 7 and Table 4 for further wire harness adapter description.

3.Plug the 6-pin connector found on the ST9101 wiring adapter directly to the open 6-pin connector on the new ST9120B,U control board.

4.Take the two remaining white wires on the ST9101 wiring adapter and connect to Neutral quick connect terminals on the ST9120B,U.

5.Take the black wire on the ST9101 wiring adapter and connect to the L1 quick connect terminal on the ST9120B,U.

6.Take the blue wire on the ST9101 wiring adapter and connect to the IND quick connect terminal on the ST9120B,U.

7.Identify the model number of the board being replaced and set the dip switches based on Table 3.

8.Check proper connection using Fig. 3.

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ST9120B,U UNIVERSAL ELECTRONIC FAN TIMERS

Table 1. ST9101 to ST9120B,U Wiring Conversions.

ST9101	ST9120	ST9141	ST9160	ST9120B,U
HEAT	HEAT	HEAT	HEAT	HEAT
COOL	COOL	COOL	COOL	COOL
	CONT	CONT	CONT	CONT
ACC	---	---	---	* for systems with one
				ON fan speed (see
				note below)
	DI	DI	---	IND
S	S1 to S3	S1 to S3	L1	L1
M1	UNUSED MOTOR LEADS	UNUSED MOTOR LEADS	M1	UNUSED
M2	UNUSED MOTOR LEADS	UNUSED MOTOR LEADS	M2	UNUSED
N	N	N	N	N
X	X	XI	24 VAC	X
C	C	C	COM	C
---	SPEED UP	SPEED UP	---	---
---	Z1	Z1	TWIN H	** TWIN (see note
				below)
---	Z2	Z2	TWIN C	** TWIN (see note
				below)
---	---	---	DATA	DATA
Thermostat	Terminals
R	R	R	R	R
Y	Y	Y	Y	Y
C	C	C	C	C
W	W	W	W	W
G	G	G	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 ST9120B,U 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 ST9120B,U.

**TWIN terminal is used to interconnect two ST9120B,U units to operate blower outputs simultaneously. Twinning at new ST9120B,U control is not backwards compatible with legacy controls.

ST9141 to ST9120B,U Wiring Conversion Instructions

1.Turn off power to appliance and carefully remove each wire and connect directly to the new ST9120B,U control board before removing the existing control. Use Table 1 to determine the proper ST9120B,U terminal for each corresponding ST9141 connection. Be careful to directly connect the new terminal or label each wire prior to removal from original board.

2.Unplug the 9-pin connector and plug existing wiring harness directly into the 9-pin connector found on the ST9141 wiring adapter 50034962. See Fig. 8 and Table 5 for further wire harness adapter description.

3.Plug the 6-pin connector found on the ST9141 wiring adapter directly to the open 6-pin connector on the new ST9120B,U control board.

4.Take the gray wire on the ST9141 wiring adapter and connect to the LIM quick connect terminal on the ST9120B,U.

5.Take the brown wire on the ST9141 wiring adapter and connect to the PRSW quick connect terminal on the ST9120B,U.

6.Identify the model number of the board being replaced and set the dip switches based on Table 3.

7.Check proper connection using Fig. 4.

ST9160 to ST9120B,U Wiring Conversion Instructions

1.Turn off power to appliance and carefully remove each wire and connect directly to the new ST9120B,U control board before removing the existing control. Use Table 1 to determine the proper ST9120B,U terminal for each corresponding ST9160 connection.

2.Unplug the 6-pin connector and plug it into the J3 connector found on ST9120B,U.

3.Plug the jumper plug into the J1 connector at ST9120B,U.

4.Identify the model number of the board being replaced and set the dip switches based on Table 3.

5.Check proper connection using Fig. 5 or 6.

LED Diagnostic

The ST9120 control provides the following status information and diagnostic troubleshooting code sequence as shown in Table 2.

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ST9120B,U UNIVERSAL ELECTRONIC FAN TIMERS

		Table 2. LED Diagnostic Troubleshooting Codes.
No. of flashes		Condition
dim/on (heartbeat)		Device works correctly.
1		Limit switch (ST9120) or burner limit switch (ST9141) is open.
2		Primary limit switch (ST9141) is open.
3		Pressure switch is improperly closed or pressure switch open when inducer blower has been
		running for >30 sec.
4		Control is in lockout due to air not circulating (overheated).
5		Smart Valve II limit switch is open.
6		Twinning communication corrupted (check system transformers' phasing).
7		Wrong 24 VAC supply condition.
		Table 3. Recommended Default Dip Switch Settings.
			Legacy Timing								New ST9120B,U
Replaced			Heat	Heat	Cool	Cool
			On	Off	On	Off	Heat On			Heat Off				Cool On			Cool Off
Control Model	Original OEM
Number		Appliance	sec	sec	sec	sec	1	sec	2		3		sec	4		sec	5	sec
ST9101A1006	Rheem		30	100	4	0	off	30	off		off		120	off		4	off	30
ST9101A1014	Rheem		30	100	4	0	off	30	off		off		120	off		4	off	30
ST9101A1022	Trade		30	100	4	0	off	30	off		off		120	off		4	off	30
ST9120A1006	Armstrong		30	100	4	0	off	30	off		off		120	off		4	off	30
ST9120A2004	Armstrong		30	140	4	0	on	30	off		on		150	off		4	off	30
ST9120B1005	Ducane		30	60	4	0	off	30	on		off		60	off		4	off	30
ST9120C1012	Snyder General		60	100	4	0	on	60	off		off		120	off		4	off	30
ST9120C1020	Nordyne		60	100	4	0	on	60	off		off		120	off		4	off	30
ST9120C2002	York		30	100	4	30	off	30	off		off		120	off		4	off	30
ST9120C2010	Ducane		30	100	4	30	off	30	off		off		120	off		4	off	30
ST9120C2028	Armstrong		30	100	4	60	off	30	off		off		120	off		4	on	60
ST9120C3000	ICP		30	140	30	30	off	30	off		on		150	on		30	off	30
ST9120C3018	Bard		60	100	4	60	on	60	off		off		120	off		4	on	60
ST9120C4008	ICP		30	140	30	30	off	30	off		on		150	on		30	off	30
ST9120C4016	ICP		30	140	30	30	off	30	off		on		150	on		30	off	30
ST9120C4040	ICP		30	140	30	30	off	30	off		on		150	on		30	off	30
ST9120C4057	ICP		30	140	30	30	off	30	off		on		150	on		30	off	30
*ST9120C5005	ICP		30	140	4	30	off	30	off		on		150	off		4	off	30
*ST9120C5013	ICP		30	140	4	30	off	30	off		on		150	off		4	off	30
*ST9120D3009	Goodman		30	140	4	60	off	30	off		on		150	off		4	on	60
ST9120G2008	ICP		60	100	30	0	on	60	off		off		120	on		30	off	30
ST9120G2016	ICP		30	100	30	30	off	30	off		off		120	on		30	off	30
ST9120G2024	Skymark		30	60	30	30	off	30	on		off		60	on		30	off	30
ST9120G2032	Skymark		30	60	4	100	off	30	on		off		60	off		4	on	60
ST9120G4004	ICP		30	140	30	30	off	30	off		on		150	on		30	off	30
ST9120G4012	ICP		30	140	30	30	off	30	off		on		150	on		30	off	30
ST9120G4038	Trade		30	140	30	30	off	30	off		on		150	on		30	off	30
ST9120U1003	Trade		30	140	4	30	off	30	off		on		150	off		4	off	30
ST9141A1002	Consolidated		30	140	6	60	off	30	off		on		150	off		4	on	60
	Industries
ST9141A1028	Consolidated		30	140	6	60	off	30	off		on		150	off		4	on	60
	Industries
ST9141B1001	Consolidated		75	180	6	60	on	60	on		on		180	off		4	on	60
	Industries
ST9150A1003	Consolidated		36	168	7	72	off	30	on		on		180	off		4	on	60
	Industries

*Heat fan off delay setting may need adjustment based on performance. See Fig. 10 to adjust timings.

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ST9120B,U UNIVERSAL ELECTRONIC FAN TIMERS

Table 3. Recommended Default Dip Switch Settings. (Continued)

		Legacy Timing								New ST9120B,U
Replaced		Heat	Heat	Cool	Cool
		On	Off	On	Off	Heat On			Heat Off			Cool On			Cool Off
Control Model	Original OEM
Number	Appliance	sec	sec	sec	sec	1	sec	2		3	sec	4		sec	5	sec
ST9150B2000		36	144	7	0	off	30	off		on	150	off		4	off	30
ST9150B2018	ICP	30	140	30	30	off	30	off		on	150	on		30	off	30
ST9150B2026	Ducane	36	144	7	36	off	30	off		on	150	off		4	off	30
ST9150B2034		36	144	7	36	off	30	off		on	150	off		4	off	30
ST9160A1002	Armstrong	30	90	6	60	off	30	off		off	120	off		4	on	60
ST9160B1001		30	120	6	30	off	30	off		off	120	off		4	off	30
ST9160B1019		30	120	6	30	off	30	off		off	120	off		4	off	30
ST9160B1027		30	120	6	60	off	30	off		off	120	off		4	on	60
ST9160B1035		30	120	6	30	off	30	off		off	120	off		4	off	30
ST9160B1043	ICP	30	140	6	30	off	30	off		on	150	off		4	off	30
ST9160B1050	ICP	30	140	6	60	off	30	off		on	150	off		4	on	60
ST9160B1068	Armstrong	30	120	6	60	on	30	off		off	120	off		4	on	30
ST9160B1076	Ducane	30	120	6	30	off	30	off		off	120	off		4	off	30
ST9160B1084	ICP	30	140	6	90	off	30	off		on	150	off		4	on	60
ST9160C1000		30	140	30	30	off	30	off		on	150	on		30	off	30
ST9160C1018		30	140	30	30	off	30	off		on	150	on		30	off	30
*ST9120B,U Factory Default						off	30	off		off	120	off		4	off	30
Setting

*Heat fan off delay setting may need adjustment based on performance. See Fig. 10 to adjust timings. NOTE: Timings may not be exactly the same as the replaced control and adjustments may need to be made.

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ST9120B,U UNIVERSAL ELECTRONIC FAN TIMERS

HUMIDIFIER

INDUCER

AIR

CLEANER

TO 115/230 VAC

POWER SUPPLY

FUSE

L1 (HOT)

L2 (N)

FAN

STARTING

CAP

1

HI

NEUTRAL

UNUSED

HUM

IND

L1

CONT

EAC

COOL

HEAT

ML

MH

LO

2

J3

STATUS

DELAY

LIMIT

115/230 VAC

SWITCH

TWIN

TRANSFORMER

ROLLOUT

24 VAC

FUSE

SWITCH

J1

PRESSURE

C

X

LIM PRSW Y

C

C

G

Y

W

R

SWITCH

MV

MV/PV PV

MV MV/PV PV BRN 24V 24V SPARK

GND

C G Y W R

S8600 IGNITION CONTROL

THERMOSTAT

GND

SENSE

PILOT

BURNER

1 CONNECT ONLY IF CONTINUOUS SPEED IS AVAILABLE AND USED.

DENOTES LINE VOLTAGE WIRING

2

CONNECT ONLY IF CONTINUOUS SPEED IS NOT USED.

DENOTES LOW VOLTAGE WIRING

M27704

Fig. 1. Typical ST9120B,U wiring connections in ST9120 system with S8600 Intermittent Pilot Ignition Control.

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6

ST9120B,U UNIVERSAL ELECTRONIC FAN TIMERS

HUMIDIFIER	INDUCER
	AIR CLEANER

TO 115/230 VAC

POWER SUPPLY

FUSE

L1 (HOT)

L2 (N)

FAN

STARTING

CAP

1

HI

NEUTRAL

ML

MH

UNUSED

HUM

IND

L1

CONT

EAC

COOL

HEAT

LO

2

24 VOLT

COMMON

24 VOLT

J3

HOT

EFT

STATUS

DELAY

OUTPUT

24 VOLT

THERMOSTAT

OR PRESSURE

SWITCH

TWIN

115/230 VAC

TRANSFORMER

FUSE

24 VAC

ROLLOUT

LIMIT

SWITCH

SWITCH

J1

C

X

LIM PRSW Y

C

C

G

Y

W

R

SV9500

HOT SURFACE

IGNITION CONTROL

C G Y W R

THERMOSTAT

PRESSURE SWITCH

1 CONNECT ONLY IF CONTINUOUS SPEED IS AVAILABLE AND USED.

DENOTES LINE VOLTAGE WIRING

DENOTES LOW VOLTAGE WIRING

2 CONNECT ONLY IF CONTINUOUS SPEED IS NOT USED.

M27705

Fig. 2. Typical ST9120B,U wiring connections in ST9120 system with SV9500/SV9501 SmartValve™ Control.

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ST9120B,U UNIVERSAL ELECTRONIC FAN TIMERS

FAN

STARTING

MAIN

CAP

HI

LIMIT

NEUTRAL

UNUSED

HUM

IND

L1

CONT EAC COOL

HEAT

LO

ROLLOUT

HL

HH

VENT

AUX

J3

TO 115/230 VAC

STATUS

DELAY

POWER SUPPLY

L2 (N)

FUSE

L1 (HOT)

WIRE HARNESS ADAPTER

TWIN

115/230 VAC

1

L2 WHITE

TRANSFORMER

INDUCER

2

L2 WHITE

3

FUSE

24 VAC

3

PS/MV DRIVE ORANGE

4

LIMIT RED

6

J1

5

LIMIT RED

1

GAS

6 L1 BLACK

4 NC

VALVE

7

24V GND YELLOW

2

8

MV SENSE VIOLET

5

9

INDUCER BLUE

C

X LIM PRSW Y

C

C G Y W R

PRESSURE

SWITCH

DENOTES LINE VOLTAGE WIRING

C

G

Y W R

THERMOSTAT

DENOTES LOW VOLTAGE WIRING

M27777

Fig. 3. Typical ST9120B,U wiring connections in ST9101 system.

INDUCER

AIR

HUMIDIFIER

CLEANER

TO 115/230 VAC

FUSE

POWER SUPPLY

L1 (HOT)

24 VOLT

L2 (N)

STARTING

COMMON

FAN

CAP

24VOLT

1

HI

HOT

NEUTRAL

EFT

UNUSED

HUM

IND

CONT

EAC

COOL

HEAT

ML

SWITCH

MH

24 VOLT OUTPUT

LO

THERMOSTAT

OR PRESSURE

2

SV9500

HOT SURFACE

IGNITION CONTROL

J3

STATUS

DELAY

TWIN

115/230 VAC

N.O.

N.C.

TRANSFORMER

FUSE

24 VAC

PRESSURE

COM

ST9141 WIRE HARNESS ADAPTER

SWITCH

J1

24V RED

1

1

2

24V GNDYELLOW

2

BURNER

3

WORANGE

3

4

24VRED

4

LIMIT

5

FTVIOLET

5

BRN LIMGRAY

6

PRSWBROWN

6

C

X LIM PRSW Y

C

C

G

Y

W

R

7

PRIM LIMRED

8

N.C.

9

PRIMARY

C

G

Y

W

R

LIMIT

THERMOSTAT

		DENOTES LINE VOLTAGE WIRING	1	CONNECT ONLY IF CONTINUOUS SPEED IS AVAILABLE AND USED.
		DENOTES LOW VOLTAGE WIRING	2	CONNECT ONLY IF CONTINUOUS SPEED IS NOT USED.	M27722

Fig. 4. Typical ST9120B,U wiring connections in ST9141 system with SV9500/SV9501 SmartValve™ Control.

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ST9120B,U UNIVERSAL ELECTRONIC FAN TIMERS

HUMIDIFIER

TO 115 VAC

POWER SUPPLY FUSE

L1 (HOT)

1 L2 (N)

2

115 VAC TRANSFORMER 24 VAC

LOAD

COMMON

NEUTRAL	UNUSED	HUM	IND
		5
	J3

J1

3	C	X

DENOTES LINE VOLTAGE WIRING

DENOTES LOW VOLTAGE WIRING

	AIR CLEANER
				STARTING		PRESSURE
	4		FAN	CAP	INDUCER	SWITCH
			HI
			ML
L1	CONT EAC COOL	HEAT	MH
			LO
					NEUTRAL	HOT	LIMIT ROLLOUT
							SWITCH SWITCH
					SV9501;
					SV9520
						C1
				C
				R
				DATA
				NEUTRAL	C3	C2
				L1
C G	Y W R
							FLAME ROD
					2		HOT
							SURFACE
C G Y W R							IGNITER
THERMOSTAT

1THERE MUST BE 115 VAC CONNECTED TO L1 (HOT) ON ST9120U, ST9120B.

2APPLIANCE CHASSIS MUST HAVE RELIABLE CONNECTION TO EARTH GROUND.

3JUMPER PLUG MUST BE ATTACHED TO J1 CONNECTOR.

4CONNECT ONLY IF CONTINUOUS SPEED IS AVAILABLE AND USED.

5 CONNECT ONLY IF CONTINUOUS SPEED IS NOT USED

M16880

Fig. 5. Typical ST9120B,U wiring connections in ST9160 system with SV9510/SV9520 SmartValve™ Control.

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ST9120B,U UNIVERSAL ELECTRONIC FAN TIMERS

	HUMIDIFIER
			AIR
TO 115/230 VAC			CLEANER

POWER SUPPLY FUSE

1

L1 (HOT)

L2 (N)

PRESSURE

2

STARTING

SWITCH

INDUCER

FAN

CAP

4

HI

115/230 VAC

NEUTRAL

ML

TRANSFORMER

MH

24 VAC

HUM

IND

L1

CONT EAC COOL

HEAT

LO

COMMON

LOAD

HOT

LIMIT

ROLLOUT

5

NEUTRAL

SWITCH SWITCH

UNUSED

SV9540;

J3

SV9640

C1

C

R

24VAC

DATA

NEUTRAL

C3

C2

L1

3

C

J1

X

C G

Y W R

2

Q345

IGNITER-

C G Y W R

SENSOR

DENOTES LINE VOLTAGE WIRING

THERMOSTAT

DENOTES LOW VOLTAGE WIRING

1FOR 115 VAC / 50, 60 HZ INSTALLATIONS, THERE MUST BE 115 VAC CONNECTED TO L1 (HOT) ON ST9120U, ST9120B. FOR 230 VAC / 60 HZ INSTALLATIONS, THERE MUST BE 115 VAC BETWEEN L1 (HOT) AND APPLIANCE CHASSIS.

FOR 230 VAC / 50 HZ INSTALLATIONS, USE ONLY WITH SMART VALVE RATED FOR THE SAME LINE VOLTAGE PARAMETERS.

2APPLIANCE CHASSIS MUST HAVE RELIABLE CONNECTION TO EARTH GROUND.

3JUMPER PLUG MUST BE ATTACHED TO J1 CONNECTOR.

4CONNECT ONLY IF CONTINUOUS SPEED IS AVAILABLE AND USED.

5 CONNECT ONLY IF CONTINUOUS SPEED IS NOT USED

M27724A

Fig. 6. Typical ST9120B,U wiring connections in ST9160 system with SV9540/SV9640 SmartValve™ Control.

69-2252EF—07

10