Johnson Controls A28PJ-1 Agricultural Thermostat

The Johnson Controls A28PJ-1 is a commercial-grade two-stage temperature control engineered for precision in demanding environments such as livestock confinement, nurseries, and greenhouses. This agricultural thermostat features two SPDT switches and a liquid-filled, 1 3/8" x 2 1/4" coiled sensing bulb for high-accuracy response. Built into a rugged NEMA 4X enclosure, the unit resists moisture, dust, and corrosive vapors common in barn and dairy installations. It operates across multiple line voltages (120, 208, 240, or 277 VAC) and provides a temperature setpoint range of 30 to 110 degrees Fahrenheit. Technicians can dial in performance with a fixed 2°F differential per stage and an adjustable 2–7°F differential between stages, making it a reliable solution for complex heating and cooling sequences where dual-stage functionality is required. Note that the A28PJ-1 is functionally identical to the A28PJ-1C model.

Technical Benefits for Contractors

• NEMA 4X Protection: Corrosion-resistant housing ensures long-term reliability in high-humidity agricultural settings.
• Universal Voltage: Compatible with 120/208/240/277 VAC systems, reducing the need to stock multiple SKUs.
• Precision Staging: Adjustable differential between stages (2–7°F) allows for fine-tuned control of ventilation and heating equipment.
• Remote Bulb Sensing: The 1 3/8" x 2 1/4" coiled bulb provides fast thermal response for accurate air temperature monitoring.
• Self-Powered Sensing: High-performance liquid-filled element operates the switches without the need for an external power source.

Common Questions

What is the difference between the A28PJ-1 and the A28PJ-1C?
The A28PJ-1 and the A28PJ-1C are identical in technical specification, performance, and construction; the "C" suffix often denotes specific bulk packaging or minor regional labeling differences.

Can this thermostat control both heating and cooling simultaneously?
Yes, because it utilizes two SPDT (Single Pole Double Throw) switches, you can wire one stage for heating and the second for cooling, or use both for multi-stage heating or cooling.

Is this unit suitable for wash-down environments?
Yes, the NEMA 4X rating is specifically designed to withstand the moisture and corrosive agents found in agricultural wash-down areas and heavy industrial environments.

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.