Lennox 27J29 Limit Switch

The Lennox 27J29 Limit Switch is a critical safety component designed for precise thermal regulation in residential and light commercial HVAC systems. This automatic reset limit control features a 7-inch insert, engineered to monitor internal heat exchanger temperatures and prevent catastrophic overheating. With a cut-out temperature of 220°F and a cut-in temperature of 190°F, this switch provides a reliable 30°F differential, ensuring your furnace or air handler maintains optimal cycling without unnecessary short-cycling or thermal stress. As a veteran technician knows, maintaining the integrity of the safety circuit is paramount; this OEM Lennox replacement part is built to original factory specifications to ensure seamless compatibility with Lennox, Armstrong, and Ducane equipment. The robust construction and positive-action snap switch design provide the durability required for demanding environments, making it an essential stocked item for emergency heat calls.

• Precision Thermal Safety: Features a factory-set 220°F high-limit trip point to protect the heat exchanger from damage.
• Extended Reach: The 7" probe length allows for accurate temperature sensing in deep vestibule panels and large inducer housings.
• Automatic Reset Functionality: Automatically restores system operation once temperatures drop to 190°F, reducing homeowner downtime.
• Broad Compatibility: Genuine Lennox 27J29 component fits a wide variety of 80% and 90%+ efficiency gas furnaces.
• Durable Construction: Engineered for high-cycle reliability in residential and industrial heating applications.

What are the signs of a failing limit switch?
A faulty switch often causes the indoor blower fan to run continuously while the burners fail to ignite, or it may result in frequent "limit circuit open" fault codes on the integrated furnace control board.

Can I use a shorter insert if the 7-inch isn't available?
No. The 7-inch insert length is specific to the unit's airflow pattern. Using a shorter probe may result in delayed tripping, potentially compromising the equipment's safety.

Will this work in high-efficiency condensing furnaces?
Yes, the 27J29 limit switch is used across various Lennox platforms, provided the temperature rating and probe length match the original OEM specifications for that specific model.

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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.