Bard HVAC 8402-074BX Limit Switch

The Bard HVAC 8402-074BX Limit Switch is a critical high-limit safety control engineered for Bard wall-mount and packaged units. As an OEM L170-7F limit switch, this component is designed to break the heating circuit if internal temperatures reach a 170°F threshold, protecting the heat exchanger and blower assembly from thermal damage. This model features a manual reset mechanism, requiring a technician to physically inspect the system and clear the fault before the unit can resume operation, which is a vital safety protocol for identifying airflow or combustion issues.

For field installations and servicing, the 8402-074BX is identical to 8402-074 and serves as the direct boxed replacement for obsolete 8402-060 models. HVAC professionals often utilize this Bard limit control when troubleshooting short-cycling units or "high limit fault" codes. Its compact, metal-housing design ensures a precise fit in the furnace cabinet, maintaining consistent normally closed (NC) continuity during standard operation. Integrating this genuine Bard replacement part ensures the system remains compliant with original equipment safety standards and restores reliable high-temperature protection.

• Precise Thermal Protection: Fixed 170°F trip point ensures the system shuts down before reaching critical overheating levels.
• Manual Reset Safety: Prevents automatic restarts after a high-limit event, forcing an inspection of potential root causes like clogged filters or blower failure.
• Direct OEM Compatibility: Seamlessly replaces part numbers 8402-074 and 8402-060 without the need for mounting modifications.
• Rugged Construction: Built with a durable metal housing and a sensitive internal diaphragm for long-term reliability in demanding commercial environments.

• Why does my Bard unit keep tripping the 8402-074BX limit? Frequent tripping usually points to restricted airflow, such as a dirty air filter, blocked return vents, or a failing blower motor that isn't pulling enough heat off the exchanger.
• How do I test the L170-7F switch in the field? Use a multimeter to check for continuity across the terminals. At room temperature, the switch should be normally closed (0.0 ohms). If it shows an open circuit when cool, the switch has failed or needs a manual reset.
• Can I bypass the limit switch for testing? While jump-testing can confirm a faulty switch, never leave a unit running with a bypassed limit. It is a fundamental safety hazard and can lead to catastrophic equipment failure.

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.