Johnson Controls T-4756-201 Thermostat

The Johnson Controls T-4756-201 is a professional-grade pneumatic heating-cooling thermostat engineered for high-volume air distribution in commercial HVAC systems. This dual temperature control unit operates with distinct pressure actions: 15 psig direct acting for heating and 20 psig reverse acting for cooling. Designed for horizontal mounting, this robust controller ensures seamless transitions between seasonal cycles by managing pneumatic actuator signals with precision. The high-volume output capability reduces the need for additional relay volume boosters in larger zones, maintaining tight setpoint stability and system responsiveness. Whether you are performing a pneumatic system calibration or replacing a legacy JCI T-4000 series device, the T-4756-201 provides the reliable throttling range and sensitivity required for complex branch line configurations. Its rugged internal construction is built to withstand the continuous cycling typical of commercial HVAC control systems, making it a staple for contractors maintaining pneumatic infrastructure.

Key Benefits for Technicians:

• Dual Action Versatility: Integrates both heating and cooling logic into a single horizontal pneumatic thermostat footprint.
• High Volume Output: Delivers sufficient air flow to drive multiple actuators directly without significant signal lag.
• Field Calibration: Allows for precise adjustments to the throttling range and setpoint to match specific zone requirements.
• System Compatibility: Operates efficiently within standard pneumatic control loops using filtered, dry instrument air.

Common Technical Questions:

How do I switch between heating and cooling modes?
The T-4756-201 automatically switches based on the supply air pressure; it operates as direct acting at 15 psig and reverse acting when the main pressure is increased to 20 psig.

What is the proper mounting orientation for this model?
This specific model is calibrated for horizontal mounting. Installing it vertically can affect the internal flapper-nozzle assembly and lead to setpoint drift.

Can this thermostat replace a single-temperature unit?
Yes, provided your system is designed for a changeover supply pressure and you require the high-volume output for your branch line actuators.

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.