Johnson Controls T-4756-202 Thermostat

The Johnson Controls T-4756-202 is a high-performance pneumatic heating-cooling thermostat designed for precision control in commercial HVAC systems. This dual temperature pneumatic thermostat features high-volume output capability, ensuring responsive actuation of terminal devices like valves and dampers. Operating with a 15 psig direct acting heating signal and 20 psig reverse acting cooling signal, the T-4756-202 is engineered for vertical mounting and seamless integration into existing Johnson Controls pneumatic systems. The unit utilizes a bimetal sensing element to provide accurate setpoint maintenance in demanding environments where electronic controls are impractical. Its rugged construction facilitates long-term stability in high-traffic mechanical rooms, making it a standard choice for contractors managing legacy pneumatic retrofits. For technicians, the clear pressure output signals and reliable sensitivity adjustments allow for rapid calibration of pneumatic controls and efficient system balancing.

Key Benefits

• Dual Action Versatility: Supports both direct acting heating and reverse acting cooling configurations within a single unit.
• High Volume Output: Reduces lag time by providing sufficient airflow to drive multiple actuators without the need for additional relays.
• Standardized Mounting: Designed for vertical pneumatic thermostat installations, ensuring compatibility with existing wall boxes and trim plates.
• Field Serviceable Design: Built with accessible components for straightforward maintenance and calibration during routine inspections.

Common Questions

How do I calibrate the setpoint on the T-4756-202?
Calibration involves adjusting the setpoint dial and verifying the pneumatic control pressure at the test port using a calibrated gauge to ensure the output matches the required branch line pressure.

Is this model compatible with non-Johnson Controls systems?
Yes, as long as the supply air pressure and signal requirements (15/20 psig) align with the system’s design specifications for heating and cooling cycles.

What is the typical application for a high volume output thermostat?
These are primarily used in zones where rapid response is required or where the thermostat must control a large number of pneumatic actuators simultaneously.

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.