Rheem-Ruud 47-21711-11 Limit Switch

The Rheem-Ruud 47-21711-11 Limit Switch is a critical safety component designed for precise thermal regulation in HVAC furnace systems. As a genuine OEM replacement part, this normally closed (SPST) switch is engineered to disrupt the burner circuit if internal plenum temperatures exceed safety thresholds. It features a fixed open temperature of 180°F and a fixed close temperature of 160°F, providing a 20°F differential that prevents rapid cycling of the equipment. This board-mounted limit control utilizes a 7-inch insertion length to monitor airflow deep within the heat exchanger assembly, ensuring accurate high-limit protection. Designed for high-duty cycles, the auto-reset functionality restores operation once temperatures return to the 160°F setpoint. This furnace high limit switch is compatible with numerous Rheem and Ruud gas furnaces, including RGEC, RGED, and RGKB series, replacing legacy part numbers 47-42360-11 and 8404-5594. Its 90-degree strap angle and 1/4-inch quick connect terminals allow for straightforward integration into existing control boards.

• Precision Thermal Monitoring: Factory-calibrated 180°F trip point ensures reliable overheat protection for the heat exchanger.
• OEM Compatibility: Exact drop-in replacement for Protech and Rheem-Ruud hardware, maintaining the original equipment's safety listing.
• Durable Construction: Features a 36T series TOD switch housed with an enclosed disc face to protect contacts from combustion byproducts.
• Standardized Electrical: Rated for 120/230VAC applications with a 15A/10A current capacity to handle standard inducer or gas valve circuits.
• Automatic Reset: Eliminates manual intervention by resetting the circuit once the system cools to 160°F.

What causes a Rheem furnace limit switch to trip?
A trip usually indicates restricted airflow, often caused by a dirty air filter, blocked return vents, or a failing blower motor. If the 47-21711-11 continues to open, professional diagnostic of the static pressure is recommended.

Can I use a switch with a shorter insertion length?
No. The 7-inch insertion length is specific to the furnace's heat exchanger geometry. Using a shorter probe may result in delayed response times, potentially causing damage to the unit before the switch triggers.

Is this switch compatible with 24V control circuits?
Yes, while it is rated for up to 230VAC, this SPST normally closed switch is commonly used in 24V safety strings to break power to the gas valve or ignition control board.

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.