A28GJ-33C Johnson Controls Temperature Control

Overview

The Johnson Controls A28GJ-33C is a heavy-duty, two-stage mechanical temperature control designed for precise thermal management in commercial HVACR and industrial process applications. This remote bulb thermostat features a liquid-filled sensing element, dual SPDT switches for independent circuit control, and an open-frame design engineered for seamless integration into existing custom control panels or equipment housings.

Features

• Dual-Stage Control: Features two independent SPDT switches to allow sequenced management of multi-stage heating or cooling loads, or triggering high/low temperature alarms.
• Easy Adjustment: Includes a visible knob-style range adjuster for quick, tool-free field setpoint configuration.
• Adjustable Inter-Stage Differential: Permits technical calibration between the first and second stage sequencing to prevent short cycling.
• Mechanical Operation: Employs a liquid-filled remote sensing bulb and capillary that functions reliably without requiring external power to the controller itself.
• Panel-Ready Layout: Open construction with no enclosure simplifies direct installation inside protected electrical enclosures or equipment housings.

Specifications

• Brand: Johnson Controls
• Model/SKU: A28GJ-33C
• Control Type: Two-Stage Temperature Control
• Switch Type: Two SPDT (Single-Pole, Double-Throw) Switches
• Setpoint Range: 60°F to 90°F
• Capillary Length: 60 inches (5 feet)
• Sensing Bulb Size: 3/8 inch diameter x 3-1/2 inch length
• Voltage Rating: Multi-voltage support (120 / 208 / 240 / 277 VAC)
• Enclosure: Open construction (None)

Applications

Well-suited for commercial and industrial HVAC applications requiring reliable two-stage temperature switching. Common uses include managing fan coil units, air handling units, industrial refrigeration systems, hydronic heating or cooling configurations, and multi-stage heating or ventilating sequencing.