The Cleveland Controls AFS-271 is a professional-grade air pressure sensing switch designed for critical proving switch applications in HVAC and energy management systems. This adjustable air flow switch offers a precise set point range of 0.05" to 2.0" w.c., making it an essential component for monitoring positive, negative, or differential pressure in commercial burners and furnaces. Engineered with a durable plated housing and a silicone diaphragm, the AFS-271 utilizes a snap-acting SPDT switch to provide reliable electrical switching under low-pressure conditions. Techs should note the 1/4" 90-degree quick-connect terminals and the dual 7/16"-24 UNS 2A threaded sample line connectors, which include integral compression nuts and ferrules for 1/4" OD tubing. For optimal accuracy and to achieve the 0.05" minimum set point, ensure the device is mounted with the diaphragm in a vertical plane. This unit is rated for 300 VA pilot duty and can withstand temperatures from -40°F to 180°F, ensuring stability in demanding mechanical rooms. Key Benefits Versatile Pressure Sensing: Capable of sensing positive, negative, or differential pressure for comprehensive system monitoring. Field Adjustable Range: Features a wide 0.05" to 2.0" w.c. range, allowing for precise calibration on-site using the top-mounted adjustment screw. Industrial Build Quality: Zinc-plated housing and 100,000-cycle life expectancy ensure long-term reliability in fuel-burning equipment. Secure Connections: Equipped with compression ferrule connectors to prevent air leaks in sensing lines. Common Questions How do I calibrate the set point for specific duct velocities? Use a digital manometer to monitor the actual pressure while turning the adjustment screw; each full turn represents approximately 0.2" w.c. Always calibrate the switch after the system has reached operating temperature. Can this switch be used to monitor combustion by-products? Yes, the AFS-271 is designed to handle air and combustion by-products that are non-corrosive to silicone diaphragms. What is the maximum pressure limit for the sensing diaphragm? The unit is rated for a maximum pressure of 0.5 psi (13.85" w.c.). Exceeding this limit may damage the internal spring or diaphragm mechanism. 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.
