ST9120U1003Universal Electronic

Fan TimerTraining Module

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• Product Overview• Set Up• Installation• Troubleshooting• Product Cross Reference• ST9120 Advantage

ST9120U - What You Will Learn:

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What is the ST9120U Electronic Fan Timer?

• A universal electronic fan timer that integrates control of all combustion blower and circulating fan operations in a gas warm air appliance

- Monitors the thermostat for heat, cool and fan demands.

- Runs the induced draft blower motor and runs the circulating fan (up to two speeds) as needed.

- Monitors limit switch strings and energizes ignition control.

- Central wiring point for the electrical components of the furnace. Saves time! One part number:

ST9120U1003

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ST9120U Electronic Fan Timer Features

• Why choose the Honeywell ST9120U?

• Universal application• Replaces over 25 existing Honeywell controls

• Easy installation• DIP switch selectable circulating fan delays

• Heat on/off delay• Cool on/off delay (cool off fixed at 30 seconds)

Single model services multiple furnace applications Included with the ST9120U:

• Wiring information and adapter for the ST9101• Original appliance application• Delay timing recommendation

• Quality construction for a long service life

Installation

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Installation of the ST9120U

• Location and Mounting- Mount the ST9120U Electronic Fan Timer in the appliance wiring

compartment or furnace vestibule

- Mounting screws provided

• Wiring- Make sure that all wiring complies with local codes and

ordinances.

- Disconnect power before making wiring connections.

Set-Up

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Set up of the ST9120U

• Setting DIP switches- Heat fan-on delay

On: 30/60 Seconds Starts timing when main valve energized

- Heat fan-off delay Off: 60/100/140/180 Seconds Starts timing when main valve is de-energized

- Cool fan-on delay On: 4/30 Seconds Starts with call for cooling

- Cool fan-off delay fixed at 30 seconds

- Post Purge: 5 seconds

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Set up of the ST9120U

Recommended dip switch settings are included in the installation instructions as well as the Honeywell Residential Combustion Application and Selection Guide.

Troubleshooting

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Troubleshooting of the ST9120U

• Look for appropriate voltages at the ST9120U terminals

• Check operation and timing of:- Combustion blower

- Fan at heating speed

- Fan at cooling speed

• Check limit operation and system response

Note: The ST9120U schematics show internal switching to clarify operation and assist in troubleshooting.

Product Cross Reference

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Product Cross Reference

The ST9120U replaces over 25 existing Honeywell controls:

ST9101A1006 ST9120C1020 ST9120C4016 ST9120G2016

ST9101A1014 ST9120C2002 ST9120C4040 ST9120G2024

ST9101A1022 ST9120C2010 ST9120C4057 ST9120G2032

ST9120A1006 ST9120C2028 ST9120C5005 ST9120G4004

ST9120A2004 ST9120C3000 ST9120C5013 ST9120G4012

ST9120B1005 ST9120C3018 ST9120D3009 ST9120G4038

ST9120C1012 ST9120C4008 ST9120G2008  

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Product Cross Reference

• Where do I find Honeywell universal fan timer cross reference information?

- www.customer.honeywell.com

- Honeywell Application Selection and Cross

Reference Guide – Form 63-9575

- Honeywell Laminated Truck Visor – Form 63-9581

- Honeywell Residential Technical Support: 1-800-468-1502

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www.customer.honeywell.com

• See Cross Reference Search box in right column.

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ST9120U Advantage

• When promoting the ST9120U keep these advantages in mind:

- The ST9120U universal control replaces over 25 existing Honeywell controls. This in turn, reduces inventory and saves time looking for the right part.

- A central wiring point for most of the electrical components of the furnace makes installation easy and gets the installer on to the next job faster.

- Easy to set selectable heat and cool on/off settings adapt to the application.

- The ST9120U makes the choice simple; one control saves time and money, improving your bottom line.

ST9120U1003Universal Electronic Fan Timer

Knowledge Test

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• Now that you completed this training module, take the short quiz to test your knowledge.

ST9120U Knowledge Test

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Test

1. The ST9120U Universal Electronic Fan Timer controls the blower and circulating fan in gas warm air appliances? T or F

2. The ST9120U is a central wiring point for most of the electrical components in the furnace? T or F

3. The ST9120U replaces over 25 Honeywell and competitor controls? T or F

4. The universal electronic fan timer monitors the thermostat for heat, cool and fan demands? T or F

5. The heat and cool on/off delays are set through dip switches? T or F

6. Honeywell only has one resource for cross reference information? T or F

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Answer Key

1. T2. T3. F4. T5. T6. F