Johnson Controls T-4752-202 Thermostat

The Johnson Controls T-4752-202 is a professional-grade dual temperature pneumatic thermostat engineered for precise control of heating and cooling systems in commercial HVAC environments. Operating as a two-pipe pneumatic controller, this unit features a direct acting sequence at 15 psig for heating and a reverse acting sequence at 20 psig for cooling. Designed for vertical mounting, it utilizes a sensitive bimetal element to ensure accurate thermal response and pressure output modulation. This model is a standard for facility managers maintaining pneumatic HVAC control systems, offering reliable setpoint stability without the complexity of modern electronics. It is essential to note that the T-4000 series thermostat requires a separately ordered cover and mounting bracket for field installation. When calibrating, ensure the supply air is clean and dry to maintain the integrity of the pneumatic pilot positioner and internal air capillaries.

• Dual-Action Logic: Provides seamless transition between 15 psig DA heating and 20 psig RA cooling cycles.
• Field Calibration: Features accessible adjustment screws for precise setpoint alignment and throttling range tuning.
• High-Flow Capacity: Designed for rapid response times in large-scale air handling units and terminal reheat coils.
• Rugged Construction: Built to withstand the high-vibration and variable-pressure environments typical of mechanical rooms.

How do I switch between heating and cooling modes on the T-4752-202?
The mode change is triggered by supply air pressure. At 15 psig, the thermostat operates in direct acting mode for heating; increasing the branch line pressure to 20 psig shifts the internal logic to reverse acting for cooling applications.

Is this model compatible with horizontal mounting brackets?
No, the T-4752-202 is specifically calibrated for vertical mounting. Installing it horizontally will cause gravity-induced inaccuracies in the bimetal sensing element and lead to setpoint drift.

Does this unit include the external scaleplate and dial?
The base unit includes the internal mechanism and setpoint dial, but the decorative thermostat cover and specific mounting bracket must be ordered separately to match your existing hardware finish.

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.