Johnson Controls T-4506-201 Thermostat

The Johnson Controls T-4506-201 is a high-volume output dual temperature pneumatic thermostat engineered for precise day/night or two-set-point environmental control. This direct acting controller features a horizontal mounting configuration and is equipped with a manual indexing switch, allowing technicians to restore day settings locally during night cycles without disrupting the broader system. Operating with a 55 to 85 degree dial range, the unit manages set-point transitions via supply pressure changes; typically, a 15 PSIG supply activates the lower element, while 20 PSIG engages the upper element. The calibrated switchover at 17 PSIG ensures seamless handoffs between heating and cooling or occupied and unoccupied modes. With a substantial 400 SCIM flow capacity and a minimal 20 SCIM air consumption, this thermostat minimizes demand on control air systems while maintaining responsive proportional output. The T-4506-201 is designed for rigorous commercial HVAC applications, utilizing bimetal sensing for steady performance across a 13 to 25 PSIG supply pressure range.

• Dual Dial Control: Provides independent set points for day and night cycles, increasing system flexibility.
• Integrated Indexing Switch: Enables manual override at the unit level, which automatically resets during the next day cycle.
• High Flow Capacity: The 400 SCIM output ensures rapid response times for pneumatic actuators and dampers.
• Adjustable Sensitivity: Factory set at 2.5 PSIG/°F, but field-adjustable from 0.75 to 4.0 PSIG/°F to match specific building loads.
• Rugged Design: Built for technical environments with high vibration and shock resistance to maintain calibration settings.

How does the switchover between day and night set points function?
The T-4506-201 utilizes supply pressure to toggle between dials. By increasing the header pressure from 15 PSIG to 20 PSIG, the thermostat shifts internally to the night set point. The internal switch is calibrated to trigger at approximately 17 PSIG.

Can I manually override the night setting for a single zone?
Yes, the indexing switch on this model is specifically designed for local override. Pushing the switch restores the "day" element control even if the main supply is at 20 PSIG. It will stay latched until manually released or until the system supply pressure drops back for the next day cycle.

What air connections are required for installation?
The unit features two barbed fittings for 5/32-inch O.D. polytubing, clearly marked as "S" for supply pressure and "O" for the output signal to the controlled equipment.

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.