Honeywell ST9103A User Manual

ST9103A

Electronic Fan Timer

APPLICATION

The ST9103A Electronic Fan Timer integrates control of all burner and circulator fan operations in an oil furnace. This control is the central wiring point for most of the electrical components in the furnace. The basic purposes of the ST9103A are to monitor the thermostat for heat, cool, and fan demands and run the oil burner primary control and up to a two-speed circulating fan as required. The ST9103A also monitors a limit switch string, which energizes the circulating fan whenever the limit switch opens.

Electronic air cleaner and humidifier convenience terminal connections may be provided as an option. A means for operating continuous indoor air circulation is also available as an option.

INSTALLATION INSTRUCTIONS

2.Check the ratings and specifications given in the Instructions and on the product to assure 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.

CAUTION

Disconnect power supply before wiring to prevent electrical shock or equipment damage.

Location and Mounting

The ST9103A is mounted in the appliance wiring compartment using four No. 6 screws (obtained locally) through standoffs on the corners of the board.

SPECIFICATIONS

Electrical Ratings:

Power Requirements:

Voltage: 18-30 Vac, 50/60 Hz. Current: 4 VA at 24 Vac.

Contact Ratings:

Circulating Fan: 15A Full Load, 30A Locked Rotor at 115 Vac (includes optional EAC load).

On/Off Delay Settings:

Delay On: 30 seconds, fixed.

Delay Off: 60, 90, 120, 150 seconds, field-adjustable. Timing Tolerance: larger of ±20% or 5 seconds.

Envrionmental Ratings:

Temperature: -40 to +150° F [-40° to +66° C]. Humidity: 95% maximun, noncondensing.

INSTALLATION

When Installing this Product...

1.Read these instructions carefully. Failure to follow them could damage the product or cause a hazardous condition.

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.

Setting the Heat Fan Off Delay Switches

Set the heat fan off delay switches to either 60, 90, 120, or 150 seconds, as shown in Fig. 3. The off delay time starts when the burner motor is de-energized at the end of a thermostat call for heat.

CHECKOUT

Assure the system operates properly by operating the system through at least one complete heating cycle and cooling cycle, if applicable. Troubleshoot by checking for appropriate voltages at the ST9103A terminals controlling the burner motor and heat and cool speed circulating fan. The ST9103A schematic shows internal switching to clarify operation and assist in troubleshooting. See Fig. 2.

Copyright © 1997 Honeywell Inc. • All Rights Reserved

X-XX UL

69-0771B

S9103A ELECTRONIC FAN TIMER

L2 (N)

TO 120 VAC

L1 (H)

POWER SUPPLY

FUSE

INTERLOCK

STARTING

CAP

LO

120

ML

VAC

MH

HI

CIRCULATING

FAN

24

VAC

ST9103

1

UNUSED

3

1

2

3

4

5

MOTOR

H

U

M

X

B

1

2

C

C

H

6

7

U

E

R

A

O

O

E

N

O

A

N

C

C

E

T

L

T

R

BURNER

MOTOR

LIMIT

CONTROL

THERMOSTAT

W

Y

G

R

G

W

R

Y

C

1

L2

ORANGE

T1

T2

L1

(BLACK)

(WHITE)

R8991

OIL PRIMARY CONTROL

FLAME DETECTOR

1 DENOTES STANDARD TERMINAL.

DENOTES OPTIONAL TERMINAL.

	CAD CELL
NOTE:	M5551
	DENOTES LINE VOLTAGE CONNECTIONS.
	DENOTES LOW VOLTAGE CONNECTIONS.

Fig. 1. Typical ST9103A wiring connections.

69-0771B

2

		S9103A ELECTRONIC FAN TIMER
	TO 120 VAC
	POWER SUPPLY
	FUSE
	INTERLOCK
		N3
	ELECTRONIC	1
	AIR CLEANER
S2	(OPTIONAL)	N1
		MED

		K2		HEAT
	K1	K2		COOL
						HIGH			N2
	K1			CONSTANT	1	LOW			CIRCULATION
									BLOWER
						M1	MED-HIGH
							1
						M2
	CN6-9			CN6-1		CN6-2		CN6-4
						L1	L2
						R8991
		LIMIT				OIL PRIMARY
						CONTROL
						CN6-7
						BURNER
						MOTOR
						CN6-8		CN6-5
						HUM		N7
						HUMIDIFIER
						(OPTIONAL)
						1		N6
						ACCESSORY
						(OPTIONAL)
						S1
						120 VAC	N4
						S3
						24 VAC
						C	X
									R
						ST9103A OIL	R8991
						ELECTRONIC			W
						FAN TIMER	LIMIT SENSOR
		T1		T2					Y
							CIRCULATION
			R8891			R8991
	CN6-3				CN6-6	CONTROL	BLOWER		G
						K3	K1	K2
									C
									THERMOSTAT
1	DENOTES OPTIONAL CONNECTIONS, COMPONENTS AND ACCESSORIES.
NOTE: DOTTED LINES REPRESENT PRINTED CIRCUIT BOARD WIRING.									M5552

Fig. 2. ST9103A internal schematic.

3

69-0771B

S9103A ELECTRONIC FAN TIMER

	UNUSED	3	1	2	3	4	5	H
	MOTOR
								U	X
								M
B	1 2		E	C	C	H	6	7
U				O	O	E
R			A						C
N				N	O	A
			C
E				T	L	T
R

ST9103A

ON2 1

G

W

R

Y

C

ON

ON

ON

ON

1

2

1

2

1

2

1

2

60 SEC

90 SEC

120 SEC

150 SEC

DELAY OFF SWITCH SETTINGS

M5550

Fig. 3. Setting delay off switches.

ST9103 Operating Sequence.

Action

System Response

Thermostat calls for heat.

• ST9103A closes oil primary control T-T connections.

(W terminal is energized.)

• Ignition system and oil primary control start the furnace. Oil flows as long as

oil primary control senses flame.

• Burner motor is energized and heat fan on delay timing begins. When timing

is complete, the circulating fan is energized at heat speed and warm air is

delivered to the controlled space.

Thermostat ends call for heat.

• Oil primary control is de-energized, terminating the burner cycle.

(W terminal is de-energized.)

• Heat fan off delay timing begins. When timing is complete, the circulating

fan is de-energized.

• ST9103A returns to standby mode (oil primary control and circulating

fan are off).

Burner fails to light.

• Oil primary control locks out within lockout timing (timing depends on oil

primary control).

• Burner motor is de-energized.

• If heat fan has started, it continues through the selected delay off period.

Established flame fails.

• Burner motor is de-energized and oil primary control goes into recycle mode.

• If selected heat fan off delay is longer than the recycle delay timing, the

heat fan continues to run through the next trial for ignition.

Thermostat begins call for cool.

• Circulating fan is energized at cool speed.

(G and Y terminals are energized.)

• Cooling compressor turns on immediately.

Thermostat ends call for cool.

• Circulating fan and cooling compressor turn off immediately.

(G and Y terminals are de-energized.)

Thermostat begins call for fan.

• Circulating fan is energized immediately at cool speed.

(G terminal is energized.)

• ST9103A maybe factory-configured to operate heat speed in this mode.

69-0771B

4