Reznor 85449 Limit Switch

The Reznor 85449 is a critical safety component designed for precise thermal regulation in commercial gas-fired unit heaters and furnaces. This 140-200F Auto Limit Switch monitors internal air temperatures, functioning as a primary high-limit safety by interrupting the burner circuit if the heat exchanger surpasses the 200°F threshold. As an OEM replacement part, it ensures seamless compatibility with Reznor UDAP, UDAS, and UDX series heaters, maintaining the original engineering specifications for system protection.

Featuring an automatic reset mechanism, the Reznor 85449 limit control restores continuity once the temperature drops to approximately 140°F. This prevents localized overheating caused by restricted airflow, dirty filters, or blower motor failure. For any veteran technician, installing this genuine 85449 high limit switch is the standard protocol to prevent heat exchanger fatigue and ensure long-term operational reliability in demanding HVACR environments. The component is identified by a distinct yellow color dot, denoting its specific 200°F trip point for Reznor heating equipment.

Key Benefits

• Ensures equipment safety by preventing thermal runaway in Reznor unit heaters.
• Minimizes downtime with a reliable automatic reset function that restores operation after cooling.
• Direct OEM replacement ensures exact mounting and terminal alignment for faster field installations.
• Compatible with a wide range of models, including Reznor UDAP125, UDAP300, and UDX series.

Common Questions

What causes a Reznor limit switch to trip frequently?
Frequent tripping usually indicates restricted airflow. Check for clogged air filters, obstructed ductwork, or a failing blower motor that isn't pulling enough heat off the exchanger.

How do I verify if the Reznor 85449 is faulty?
Using a multimeter, check for continuity across the terminals when the unit is cool. If the switch remains open at room temperature, the internal bimetal disc has likely failed and requires immediate replacement.

Can I use a higher temperature limit switch instead?
No. It is essential to use the specified 140-200F limit control. Increasing the limit threshold bypasses critical safety designs and risks permanent damage to the heat exchanger.

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.