Resideo ST9103A1002 Electronic Fan Timer

The Resideo ST9103A1002 serves as a robust electronic fan timer for modernizing HVAC furnace controls in both oil and gas applications. As a direct replacement electronic fan timer for the legacy 20123101 model, this unit functions as the primary 18-30 Vac interface for the combustion air blower, circulating fan, and oil primary control circuit. It features a fixed 45-second heat-on delay and adjustable fan-off delay settings—configurable to 60, 90, 120, or 150 seconds—allowing techs to fine-tune furnace blower control to match specific ductwork requirements. Designed for high-duty cycles, the ST9103A1002/U operates reliably in ambient conditions ranging from -40°F to 150°F. By integrating burner operation and air circulation into a single board, it streamlines field troubleshooting and simplifies wiring for residential and light commercial forced air systems.

Key Benefits for Contractors:

• Universal Compatibility: Engineered as an OEM-grade Resideo heater control board for gas warm air appliances and oil-fired equipment.
• Field Flexibility: DIP-switch adjustable delay settings ensure optimal heat exchanger cool-down, preventing short-cycling and improving airflow efficiency.
• Simplified Installation: Standardizing on the ST9103A1002 reduces van stock by replacing multiple older fan center and timer configurations.
• Rugged Design: Built to withstand the extreme temperature fluctuations found in attic and crawlspace furnace plenums.

Common Technical Questions:

Is the ST9103A1002 compatible with cooling systems?
Yes, the board includes dedicated terminals for 18-30 Vac cooling calls, featuring a fixed 0-second cool-on and cool-off delay for immediate response to the compressor circuit.

Can I use this board to replace a 20123101 timer?
The ST9103A1002 is the designated updated version for the 20123101, maintaining terminal layout consistency for straightforward field swaps.

Does this control the combustion air blower or just the circulating fan?
This board integrates control for both the combustion air blower (inducer) and the circulating air blower, serving as the central wiring point for the thermostat and limit circuits.

Safety Info:
California Proposition 65 Warning – This product may contain materials known to the State of California to cause cancer or reproductive harm.

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.