Johnson Controls T-4002-9012 Pneumatic Thermostat

The Johnson Controls T-4002-9012 is a high-performance, single-temperature pneumatic room thermostat designed for precision control in commercial HVAC systems. As a direct-acting (DA) controller, this unit provides a proportional output air signal that increases as the space temperature rises, making it an essential component for modulating pneumatic valves and damper actuators in heating and cooling applications. Engineered for vertical mount installations, the T-4002-9012 features a bi-metal sensing element and is factory-calibrated to deliver a 56 ± 7 kPa (8 ± 1 PSIG) signal when the ambient temperature matches the dial setting.

This 2-pipe thermostat is optimized for high-volume output, utilizing pneumatic feedback to ensure rapid and stable response to load changes. With a scaling range of 12 to 30 Degrees Celsius (55 to 85 Degrees Fahrenheit), it offers a adjustable sensitivity of 0.75 to 4 PSI/F° to suit specific zone requirements. The rugged construction supports a maximum supply pressure of 25 PSIG (175 kPa), while the 5/32-inch barbed fittings allow for seamless integration with standard polyurethane tubing. For technicians performing pneumatic calibration, the integrated output test connection facilitates efficient field adjustments without disrupting the control loop.

Key Benefits

• Precision Proportional Control: Modulates pneumatic actuators with high accuracy to minimize energy waste and mechanical wear.
• High Volume Output: Features power amplification for faster response times in large-scale air handling systems.
• Versatile Application: Suitable for both heating and cooling sequences requiring a direct acting control signal.
• Simplified Installation: Standard vertical mounting design fits traditional 2-pipe terminal configurations with minimal retrofitting.
• Field Serviceable: Includes a calibration screw and test port to ensure long-term HVAC system performance.

Common Questions

How do I calibrate the T-4002-9012?
Ensure a clean, dry 20 PSIG supply. Set the dial to the current room temperature and adjust the internal calibration screw until the output pressure reaches the midpoint of your controlled device's spring range (typically 8 PSIG).

Can this replace a reverse-acting (RA) thermostat?
No, the T-4002-9012 is a direct-acting model. If your application requires the output pressure to decrease as temperature rises, you must use a reverse-acting variant like the T-4002-9013.

What air quality is required for this pneumatic controller?
The air supply must be strictly clean, dry, and oil-free to prevent clogging of the bi-metal element or internal restrictors, which could lead to control drift.

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.