Rheem-Ruud 47-21900-05 Limit Switch

The Rheem-Ruud 47-21900-05 is a professional-grade Manual Reset Limit Switch engineered for high-limit temperature protection in residential and commercial furnaces. As an OEM Rheem replacement part, this SPST normally closed switch features a fixed 200-degree F open temperature, making it a critical safety component for preventing heat exchanger failure and fire hazards. The flanged airstream mounting design ensures the thermal disc is accurately positioned to detect restricted airflow or over-firing conditions common in older gas furnace maintenance. Field technicians prioritize this disc limit switch for its reliable L200 fixed-setpoint performance and robust electrical contacts rated for 25 Amps. Utilizing a manual reset instead of an auto-reset configuration forces a technician to diagnose underlying issues like clogged filters or faulty blower motors before the system resumes operation, maintaining strict adherence to safety protocols. This component is cross-compatible with several brands under the Rheem umbrella, including Ruud, Weather King, and Corsaire, providing a versatile solution for furnace repair and restoration.

• Factory-Calibrated Precision: Fixed 200°F trip point ensures the system shuts down immediately if internal plenum temperatures exceed safe operating parameters.
• Manual Reset Safety: Prevents short-cycling and requires physical verification of equipment status before restoring the heating cycle.
• OEM Construction: Genuine Rheem-Ruud part ensures exact fitment and electrical compatibility without the terminal degradation risks of aftermarket alternatives.
• High Ampacity Rating: Durable 25 Amp construction handles the electrical load of heating control circuits and high-limit safety loops effectively.

• Why did my 47-21900-05 limit switch trip? Most trips are caused by restricted airflow, which results from a clogged air filter, blocked return air ducts, or a failing blower motor assembly.
• Can I replace an auto-reset switch with this manual reset model? No. Safety limits must be replaced with the exact reset type specified by the equipment manufacturer to maintain the system's UL listing and safety integrity.
• Where is this switch typically located? This high-limit switch is usually found on the heat exchanger firewall or inside the burner compartment where it can monitor peak airstream temperatures.

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.