ST9141A1002 Electronic Fan Timer

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

1

2

3

4

System Condition

Burner limit circuit is open.

Primary limit circuit is open.

Pressure switch circuit is improperly closed.

Control is in lockout due to air 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.

!

CAUTION

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.

69-0780

Fig. 1—Typical ST9141A1002 wiring connections.

HUMIDIFIER

AIR CLEANER

FUSE

L1 (H)

L2 (N)

TO 120 VAC

POWER SUPPLY

120 VAC

TRANSFORMER

24 VAC

COMBUSTION

BLOWER

PRIMARY

LIMIT

BURNER

LIMIT

SV9500

HOT SURFACE

PILOT IGNITION

SYSTEM CONTROL

1 2

3 DI

HUM EAC N

1 2 3 4

N

N

NEUTRAL

CIR BLWR

C X X

STARTING

CAP

CIRCULATING

FAN

LO

ML

MH

HI

THERMOSTAT

W Y G

NOTE:

R

Z1

Z2

DELAY

1 2

OFF

SPEED

UP C Y

C G Y W R

= DENOTES STANDARD TERMINAL.

= DENOTES TERMINAL NOT PROVIDED.

ST9141

DENOTES LINE VOLTAGE CONNECTIONS.

DENOTES LOW VOLTAGE CONNECTIONS.

N.C.

N.O.

COOLING

CONTACTOR

PRESSURE

SWITCH

24 VOLT

COMMON

24 VOLT

HOT

EFT

OUTPUT

24 VOLT

THERMOSTAT

OR PRESSURE

SWITCH

M5607

2

Fig. 2—ST9141A1002 internal schematic.

L1-1

K1

L1-2

K2

K2

K3A

N.O.

BURNER

LIMIT

6

PRIMARY

LIMIT

8

N.C.

3

1

CN1

X-OT

R-OT

PS1

COM.

PRESSURE

SWITCH

7 PS2

FUSE

L1

(H)

TO 120 VAC

POWER SUPPLY

L2

(N)

EAC (S)

HEAT

COOL

HUM (S)

INTERLOCK

EAC (N)

M1

M2

ELECTRONIC AIR CLEANER

LOW

MED-LOW

MED-HIGH

HIGH

CIRCULATING

FAN

HUM (N)

HUMIDIFIER

N2

N1

DI

COMBUSTION

AIR BLOWER

N3

N4

120 VAC

X

TRANSFORMER

24 VAC C

K3B

ST9141A

ELECTRONIC

FAN TIMER

FT

5

24V

4

C

2

C

G

Y

W

R

THERMOSTAT

COOLING

CONTACTOR

24V

SV9500 HOT SURFACE PILOT

IGNITION SYSTEM CONTROL

TSTAT FT GND

NOTE: DOTTED LINES REPRESENT PRINTED CIRCUIT BOARD WIRING.

M5608

3 69-0780

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

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 switching to clarify operation and assist in troubleshooting. See

Fig. 2.

Fig. 3—Setting delay off DIP switches.

ST9141

1 2

3 DI

HUM EAC N

1 2 3 4

N

N

NEUTRAL

CIR BLWR

C X X

Z1

Z2

DELAY

1 2

OFF

SPEED

UP

C Y

C G Y W R

1 2 1 2 1 2

60 SECONDS 100 SECONDS 140 SECONDS

ON

OFF

1 2

180 SECONDS

DELAY OFF DIP SWITCH SETTINGS

M5658

ST9141A1002 Operating Sequence

Action

Thermostat calls for heat.

(W terminal is energized.)

Thermostat ends call for heat.

(W terminal is de-energized.)

System Response

• 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.

• 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.

• 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.

(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 foursecond delay.

• Circulating fan is de-energized.

Thermostat ends call for fan.

(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.

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.

• Control remains in lockout until 24V power is removed and reapplied (control is reset).

• LED stops flashing.

• Normal operation resumes.

Burner limit opens.

• Circulating fan turns off after the selected heat fan off delay timing.

• LED stops flashing.

• Normal operation resumes.

• Thermostat and ignition system are de-energized and gas valve closes.

• Combustion air blower and circulating fan heat speed are energized.

• LED flashes once.

Burner limit closes.

Electronic air cleaner is connected.

(Connector to 120 Vac electronic air cleaner.)

Humidity control is connected.

(Connector to 120 Vac humidifier.)

• 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 energized when the circulating fan heat or cool speed is energized.

• Humidifier is energized when combustion air blower is energized.

5 69-0780

Home and Building Control

Honeywell Inc.

1985 Douglas Drive North

Golden Valley, MN 55422

Printed in U.S.A.

Home and Building Control

Honeywell Limited—Honeywell Limitée

740 Ellesmere Road

Scarborough, Ontario

M1P 2V9

6

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