P29AC-3C Johnson Controls Pressure Control

Overview

The Johnson Controls P29AC-3C is a professional-grade low pressure cutout control equipped with a built-in time delay relay, specifically designed for HVAC and commercial refrigeration applications. It senses pressure drops and automatically initiates a system shutdown if the pressure remains below the setpoint for a sustained period, helping to regulate pressure levels and maintain overall system efficiency. This device is engineered to provide reliable protection for chiller systems and commercial refrigeration compressors against damage caused by loss of charge or freeze-up conditions.

Features

• Auto Recycle Functionality: Automatically resets the system once pressure returns to safe operating levels, minimizing downtime and reducing the need for manual technician intervention.
• 90-Second Time Delay: Incorporates a factory-set 90-second time delay relay that prevents nuisance tripping and short-cycling caused by momentary pressure fluctuations during startup or heavy load shifts.
• Ambient Compensation: The internal thermal timing mechanism minimizes the effects of ambient temperature variations at the mounting location to maintain operational accuracy.
• Heavy-Duty Elements: Built with robust pressure elements designed to withstand excessively high overrun pressures often encountered during system testing.
• Simple Calibration: Features a single pointer scale that provides a clear, direct reading indication of the cutout pressure setpoint.

Specifications

• Pressure Range: 20 inches Hg vacuum to 100 psig (-70 kPa to 700 kPa)
• Electrical Rating: 120/240 VAC pilot duty
• Time Delay: 90 seconds (factory set and sealed)
• Element Connection: 36-inch copper capillary tube with a 1/4-inch flare nut
• Reset Type: Automatic recycling
• Maximum Allowable Test Overpressure: 325 psig (2241 kPa)

Applications

• Chiller Low Temperature Cutout: Connects to the suction side of a chiller refrigeration system to safeguard the compressor from prolonged subnormal suction pressures.
• Commercial Refrigeration: Monitors suction pressure in commercial refrigeration compressors to prevent short-cycling and structural equipment damage.
• Low Suction Pressure Monitoring: Provides general low pressure cutout control in a wide variety of commercial and industrial environmental control systems.