The Johnson Controls A19DAF-2 is a heavy-duty strap-on temperature control specifically engineered for high-limit or operating control on hot water pipes. This mechanical temperature control features a SPDT (Single-Pole, Double-Throw) switch configuration, allowing for versatile wiring as either a high-temperature cutout or a low-temperature cycle control for unit heaters. With a specialized setpoint range of 200 to 240 degrees F and a 3.5 degree F fixed differential, it provides precise thermal regulation in demanding hydronic and industrial heating environments. The A19DAF-2 is designed for surface mounting with an included adjustable strap, ensuring direct thermal contact with the pipe surface without the need for a bulb well. The concealed range adjustment prevents unauthorized tampering while maintaining a clean, professional installation. Rated for 120Vac to 240Vac, this automatic reset thermostat ensures seamless system recovery once temperatures return to the desired parameters. Key Benefits Pipe Surface Sensing: Eliminates the need for system draining or internal wells by utilizing a direct-contact strap-on surface mounted design. High-Temperature Reliability: Precision 200-240?F setpoint range ideal for high-limit safety cutouts in boiler and hydronic loop applications. Tamper Resistance: The concealed range adjustment screw ensures settings remain exactly where the technician set them. Universal Voltage Compatibility: Operates efficiently across 120Vac-240Vac electrical systems for broader site integration. Durable SPDT Switch: Provides the flexibility to open or close circuits on temperature rise, facilitating both heating and cooling logic. Common Questions How do you calibrate the setpoint on the A19DAF-2? Remove the cover to access the internal concealed range adjustment screw. Turning the screw adjusts the setpoint across the 200?F to 240?F range. Can this be used for low-temperature cutout on unit heaters? Yes, because it uses a SPDT terminal arrangement, you can wire the contacts to open on a falling temperature to prevent fan operation when the water is too cold. What is the benefit of the 3.5?F fixed differential? The fixed differential ensures a tight, predictable response time, preventing wide temperature swings and protecting sensitive system components from excessive heat. 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.
