Reznor 147677 Fan Control

The Reznor 147677 Fan Control is a critical F150-55F thermal switch assembly designed for precise airflow management in commercial unit heaters. As a secondary fan control, it ensures the blower activates and deactivates at specific temperature setpoints—typically closing at 150°F and opening at 55°F—to prevent the heat exchanger from overheating while maximizing post-cycle latent heat recovery. This OEM component comes pre-equipped with a mounting bracket and is engineered for high-temperature durability within the combustion chamber housing.

For technicians servicing UDX, UDAP, or Blower Model (UBX) units, the 147677 serves as a direct drop-in replacement for aged or drifting fan switches. Its robust microprocessor-compatible logic enables seamless integration with existing HVAC control boards and 24V or 120V fan circuits. Proper contact with the heat exchanger seam is vital; the included spring-loaded bracket ensures the sensor maintains consistent surface tension for accurate temperature sensing. This part is essential for resolving short-cycling issues or furnace lockouts caused by inadequate air transfer across the heat exchanger.

• Precise Thermal Regulation: Factory-calibrated F150-55F settings ensure optimal blower timing and system safety.
• OEM Compatibility: Authentic Reznor replacement part designed specifically for standard and high-efficiency unit heaters.
• Simplified Installation: Integrated mounting bracket facilitates rapid field replacement and secure positioning against the exchanger tube.
• Industrial Durability: Constructed to withstand the high-cycle demands of commercial HVACR environments without signal drift.

Is this compatible with older Reznor F or B series heaters?
Yes, the 147677 is often used in modern UD series and can serve as a functional replacement for older fan controls, provided the temperature setpoints and bracket clearances match the original specs.

What causes this fan control to fail?
Most failures result from carbon buildup on the sensor face or mechanical fatigue in the internal bimetal disc, leading to the blower not starting or remaining stuck on after the burner shuts down.

How do I ensure accurate temperature sensing?
Ensure the bracket holds the control approximately 1/2-inch from the heat exchanger seam without direct contact; the spring tension is designed to maintain the ideal proximity for radiant heat detection.

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.