Johnson Controls T-4756-206 Thermostat

The Johnson Controls T-4756-206 is a high volume output pneumatic thermostat engineered for precise temperature regulation in dual-temperature heating and cooling systems. Built for vertical mounting, this T-4000 series room thermostat utilizes a dual-dial configuration with independent setpoints, allowing for distinct control over heating and cooling stages without overlap. The unit functions by sensing ambient load changes and delivering a proportional output signal at 400 SCIM capacity to modulate controlled devices. It features an automatic changeover mechanism triggered by supply pressure: the device operates as 15 psig reverse acting for cooling and transitions to 20 psig direct acting for heating operations. Designed with bimetal sensing elements and internal pneumatic feedback, the T-4756-206 ensures tight accuracy and vibration resistance in demanding commercial environments. This model includes a standard Fahrenheit dial (55 to 85°F) and an output test connection for streamlined field calibration and pressure diagnostics.

• Dual-Dial Control: Separate setpoints for heating and cooling eliminate temperature overlap and improve system efficiency.
• Automatic Mode Changeover: Seamless switching between direct acting and reverse acting modes based on supply pressure (15/20 psig).
• High Volume Output: Delivers up to 400 SCIM flow capacity for rapid response in large-scale pneumatic control systems.
• Adjustable Sensitivity: Fine-tune response rates from 0.75 to 4.0 psig/°F to match specific building load requirements.
• Field Serviceability: Integrated test ports allow for branch pressure measurement and calibration without removing the unit from the wall.

How does the automatic changeover work on the T-4756-206?
The thermostat detects shifts in the main supply line pressure. At 15 psig, the unit operates in its reverse-acting cooling mode. When the system shifts to 20 psig, the internal mechanics transition to the direct-acting heating mode.

Does this thermostat include a cover?
Standard T-4000 series high-volume thermostats typically require covers to be ordered separately. Ensure you select a vertical-style cover that matches the dual-dial orientation of the T-4756-206.

Can the sensitivity be adjusted in the field?
Yes, the sensitivity is factory set at approximately 2.5 psig/°F but can be adjusted between 0.75 and 4.0 psig/°F to stabilize hunting or increase response speed depending on the actuator requirements.

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.