The Johnson Controls A19ADB-1 is a professional-grade remote bulb temperature control engineered for high-limit applications in heating, ventilation, and refrigeration systems. As a manual reset temperature switch, this controller is designed to provide critical system safety by breaking the circuit when temperatures exceed the user-defined setpoint. It features an SPST (Single-Pole Single-Throw) action that operates on an "Open High" logic, ensuring the equipment remains offline until a technician manually intervenes via the integrated reset button. Built for versatility, the electrical ratings span from 24 to 277Vac, making it compatible with a wide array of commercial HVACR power configurations. The hardware includes a 6-foot copper capillary and a 3/8" x 3 1/2" liquid-filled sensing bulb, providing reliable performance regardless of ambient temperature fluctuations around the control head. With a setpoint range of 100 to 240 degrees F and a standard knob range adjuster, this mechanical thermostat is a staple for contractors maintaining boilers, water heaters, and industrial process equipment. Its robust NEMA 1 enclosure protects the snap-acting switch mechanism, ensuring "trip-free" operation so that contacts cannot be intentionally blocked in the closed position. Key Benefits Safety Interlock: The "Open High" manual reset function serves as a dependable high-limit safety, preventing equipment damage during over-temperature conditions. Broad Compatibility: Universal 24V to 277V range allows for seamless integration into most commercial terminal boards. Durable Sensing: The 6' capillary and large bulb provide precise thermal response for remote sensing in tanks, ducts, or pipes. Contractor Friendly: Includes a visible scale and an external knob for fast, accurate setpoint adjustments in the field. Common Questions Does this unit reset automatically once the temperature drops? No, the A19ADB-1 is a manual reset control. Once the high limit is reached and the switch opens, a technician must physically press the reset button to resume operation, ensuring the cause of the high temperature is investigated. Can this be used for cooling applications? This specific model is designed to "Open High," making it a safety limit for heating. For cooling or fan-cycling applications, an "Open Low" or SPDT model would typically be required. Is the sensing element affected by the temperature at the control box? No, the liquid-filled element is designed to minimize cross-ambient effects, ensuring the switch accurately triggers based on the temperature at the bulb, not the enclosure. 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.
