Johnson Controls A28PA-2 Thermostat

The Johnson Controls A28PA-2 is a professional-grade two-stage temperature control engineered for demanding environments, including HVACR systems and agricultural facilities governed by NEC Article 547. This robust PENN thermostat features two SPDT switches within a NEMA 4X raintight and dust-tight enclosure, ensuring reliable operation in corrosive or high-moisture settings. With a broad setpoint range of 30° to 110°F and a liquid-filled 1 3/8" x 2 1/4" coiled sensing bulb, the A28PA-2 provides consistent accuracy unaffected by barometric pressure or cross-ambient temperature variations. The adjustable differential between stages (2° to 7°F) allows technicians to fine-tune sequencing for heating, cooling, or ventilation equipment. Note that the A28PA-2 is technically identical to the A28PA-2C, offering versatile multi-voltage compatibility across 120, 208, 240, and 277 VAC circuits.

Key Benefits

• Rugged NEMA 4X Protection: Corrosion-resistant thermoplastic enclosure maintains integrity in harsh agricultural and industrial wash-down environments.
• Dual-Stage Versatility: Two independent SPDT switches allow for sophisticated control of two-stage heating or cooling applications with a single device.
• Precision Sensing: The coiled copper bulb provides rapid response times and remains stable regardless of changes in surrounding ambient air pressure.
• Field-Adjustable Sequencing: Features an internal dial to set the 2/7 degree differential between stages, preventing equipment short-cycling.
• High Readability: Large, oversized markings on the range scale and an external adjustment knob facilitate easy setpoint changes in low-light conditions.

Common Questions

Each SPDT switch uses color-coded terminals. For cooling or ventilation, wire the Red (Common) to the Yellow terminal to close on temperature rise. For heating applications, wire Red to Blue to open on temperature rise.

Yes, the A28PA-2 is UL listed for NEC Article 547 agricultural environments, making it ideal for poultry houses, dairy barns, and other high-moisture agricultural facilities.

There is no functional or technical difference between these two model numbers; the units are identical in specifications, wiring, and performance.

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.