Johnson Controls A28AA-29 ,2-SPDT 2-Stage Temperature Control -30/100°F 8" Capillary

The Johnson Controls A28AA-29 is a two-stage, remote bulb temperature control ideal for maintaining consistent temperature in HVAC systems. It utilizes a liquid-filled sensor bulb connected by an 8-foot capillary tube to the main control unit. As the surrounding temperature rises, the liquid expands, triggering electrical contacts within the unit. This triggers two stages of heating or cooling depending on setpoint and differential settings. With a wide range of -30°F to 100°F, the A28AA-29 is suitable for various applications like commercial refrigeration, freezers, pool heaters, and comfort heating systems. Its two-stage functionality allows for more precise temperature control compared to single-stage models. Initially, the first stage activates to meet the desired temperature. If further adjustment is needed, the second stage kicks in, providing finer control and potentially increased energy efficiency.