Description
The Johnson Controls A28AA-29 is a precision two-stage temperature control designed for demanding commercial and industrial HVAC applications. Featuring dual SPDT (Single-Pole, Double-Throw) switch action, this controller delivers reliable sequential staging of heating or cooling equipment to optimize system efficiency and maintain tight temperature management across a wide operating range.
Key Features
- Two-stage control with 2 SPDT switch action for sequential equipment staging
- Wide voltage compatibility: 120/208/240/277 VAC — suitable for a broad range of commercial electrical systems
- Setpoint range of -30°F to 100°F for versatile low- and medium-temperature applications
- Fixed 5-degree differential per stage for consistent, reliable switching
- Adjustable 2–7 degree differential between stages for fine-tuned interstage control
- 3/8″ x 4″ sensing bulb for accurate temperature measurement
- 8-foot capillary length provides flexible installation reach
Application
The A28AA-29 is well-suited for two-stage refrigeration systems, commercial cooling equipment, and HVAC applications requiring precise multi-stage temperature control. The adjustable interstage differential allows technicians to customize the control response to match system requirements, minimizing short-cycling and maximizing equipment longevity.
Specifications
- Brand: Johnson Controls
- SKU: A28AA-29
- Control Type: Two Stage Temperature Control
- Switch Action: 2 SPDT
- Voltage: 120/208/240/277 VAC
- Setpoint Range: -30°F to 100°F
- Differential Per Stage: 5°F (fixed)
- Interstage Differential: 2–7°F (adjustable)
- Bulb Size: 3/8″ x 4″
- Capillary Length: 8 feet
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