Resideo ST9120U1011 Fan Timer

The Resideo ST9120U1011 is a universal electronic fan timer engineered to serve as a comprehensive control solution for gas warm air appliances. This furnace fan timer board integrates the management of combustion blowers and circulating fan operations into a single robust platform. Designed for field flexibility, it features DIP switch selectable delay settings that allow for precise timing adjustments. Specifically, the ST9120U1011 provides adjustable heat fan on delay (30 or 60 seconds), heat fan off delay (60, 100, 140, or 180 seconds), and a cool fan on delay (4 or 30 seconds). By replacing over 44 legacy Honeywell and Resideo models, including the ST9120C2010 and ST9141A1002 series, this board streamlines service inventory for HVAC contractors.

Built for the harsh environments of mechanical rooms, the ST9120U1011 universal replacement supports a wide ambient temperature range from -40°F to 175°F. The HVAC control board is 18-30Vac rated and monitors thermostat demands across all modes—heat, cool, and fan—while simultaneously overseeing limit switch strings and energizing ignition controls. Efficiency is further enhanced by dedicated electronic air cleaner (EAC) and humidifier (HUM) terminal connections, ensuring steady power for ancillary air quality equipment. The inclusion of diagnostic LEDs and a replaceable 3A fuse provides immediate troubleshooting feedback and circuit protection in the field.

Key Benefits for the Technician

• Universal Compatibility: Replaces more than 44 Honeywell fan timer models such as ST9101, ST9120, ST9141, and ST9160 series.
• Precise Airflow Management: Field-adjustable settings for heating and cooling cycles optimize comfort and system efficiency.
• Simplified Wiring: Includes universal interface harnesses to facilitate fast conversion and reduce labor on furnace board replacement.
• Integrated System Monitoring: Acts as the central hub for draft blowers, multi-speed circulating fans, and secondary accessories.
• Robust Protection: Equipped with a replaceable 3A automotive-style fuse to safeguard the low-voltage circuitry.

Common Questions

What models can the ST9120U1011 replace?
This universal furnace control serves as a direct cross-reference for the ST9120C2010, ST9120C2028, ST9141A1002, 1014460, ST9101, and over 40 other legacy Resideo fan timers.

How do I set the fan delays?
The board utilizes DIP switches located on the PCB. The heat fan-on and fan-off delays are field-adjustable to match the specific thermal characteristics of the appliance.

Does this board support continuous low-speed fan operation?
Yes, the ST9120U1011 provides continuous low-speed indoor air circulation when the thermostat is set to the 'On' position, independent of heating or cooling calls.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.