Johnson Controls T-4003-203 Thermostat

The Johnson Controls T-4003-203 is a high-volume output submaster pneumatic thermostat engineered for precise proportional control in complex HVAC systems. Designed for reverse acting operation, this unit utilizes horizontal mounting and is specifically calibrated for applications where a remote master controller resets the setpoint based on external variables like outdoor air temperature. With a massive 400 SCIM flow capacity and a low 20 SCIM air consumption rate, this submaster thermostat provides the rapid response required for large-volume actuators or pilot-positioning relays. It operates effectively within a 13 to 25 psig supply pressure range and features a 55 to 85 degree dial range. This Johnson Controls T-4000 series component is a critical replacement part for maintaining legacy pneumatic automation systems, ensuring stable HVAC zone control and reliable signal transmission in commercial pneumatic sequences.

• High Volume Output: High-flow design handles large pneumatic loads without the need for additional volume boosters.
• Energy Efficiency: Low air consumption minimizes the load on the instrument air compressor.
• Submaster Precision: Seamlessly integrates into existing pneumatic loops for master/submaster reset applications.
• Durable Construction: Built to withstand the rigors of mechanical rooms while maintaining calibration accuracy.

How do I calibrate the T-4003-203 submaster thermostat?
Field calibration requires a precise 0-30 psi gauge. You must adjust the sensitivity and setpoint while accounting for the master controller's signal to ensure the pneumatic control signal aligns with the desired sequence.

Can I use this as a standalone thermostat?
While functionally possible, the T-4003-203 is specifically designed as a submaster thermostat. Using it without a master controller signal may limit its ability to adjust setpoints dynamically as intended in the original system design.

What are the requirements for the air supply?
The system requires clean, dry, oil-free instrument air. A standard supply pressure of 20 psig is typical, though it is rated for 13 to 25 psig depending on your specific pneumatic HVAC configuration.

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.