T-4756-205 Johnson Controls Thermostat

Overview

The Johnson Controls T-4756-205 is a commercial-grade pneumatic heating-cooling room thermostat designed to provide individual space temperature control in building automation and HVAC systems. This high-volume output, dual-temperature, dual-dial device features a horizontal mounting configuration and accomplishes automatic mode switchover between direct and reverse actions via changes in the main supply pressure. By producing a proportional output signal, it effectively modulates pneumatic valves and damper actuators to maintain optimal indoor environmental conditions.

Features

• Dual Temperature & Dual Dial: Includes individual mechanical setpoint dials for streamlined heating and cooling management.
• Automatic Switchover: Smoothly shifts modes with a change in supply pressure, operating reverse-acting at 15 psig and direct-acting at 20 psig.
• High Volume Output: Provides an enhanced airflow capacity of 400 SCIM for responsive and stable zone control.
• Proportional Control: Delivers reliable pneumatic feedback to accurately modulate controlled equipment in response to load variations.
• Robust Design: Built to be vibration and shock resistant, meeting demanding commercial and governmental architectural requirements.

Specifications

• Brand: Johnson Controls
• Model: T-4756-205
• Control Type: Pneumatic (2-Pipe)
• Setpoint Range: 55 to 85°F (Fahrenheit scale)
• Sensitivity: Adjustable from 0.75 to 4 psig/°F (Factory set at 2.5 psig/°F)
• Operating Pressures: 15 psig Supply (Reverse Acting / Heating) and 20 psig Supply (Direct Acting / Cooling)
• Switchover Pressure: Factory calibrated at 17.5 psig
• Flow Capacity: 400 SCIM output flow capacity; 20 SCIM air consumption
• Mounting Orientation: Horizontal
• Air Connections: Barbed fittings designed for 5/32 in. O.D. polytubing

Applications

• Commercial building HVAC pneumatic control networks.
• Variable Air Volume (VAV) systems and dual-duct setups.
• Multi-zone pneumatic zoning and fan coil unit control.
• Retrofit installations and direct replacement of legacy high-volume pneumatic thermostats.