Description
The Johnson Controls A11A-1 is a low temperature cutout freezestat engineered to protect HVAC coils, air handlers, and duct systems from freeze damage. With a wide voltage compatibility range of 24 to 277Vac and a rugged SPST switching configuration, this freezestat integrates seamlessly into a broad range of commercial and residential control circuits.
The A11A-1 features a manual reset mechanism, ensuring that the system cannot automatically restart after a freeze condition is detected — a critical safety measure that requires deliberate technician intervention before resuming operation. This helps prevent repeated freeze events and protects expensive equipment from damage.
Key Features
- Voltage Range: 24 to 277Vac — compatible with a wide variety of control circuits
- Switch Type: SPST (Single Pole, Single Throw), Open on Low Temperature
- Reset Type: Manual Reset — requires intentional reset after trip, preventing automatic restart
- Cutout Temperature Range: 35°F to 45°F — adjustable to suit application requirements
- Fixed Differential: 12°F — provides consistent and predictable switching behavior
- Capillary Length: 4 feet — allows flexible installation positioning
- Sensing Element: 1/8″ diameter x 20 feet — provides broad coil coverage for accurate freeze detection
Application & Installation
The A11A-1 is designed for use in air handling units, fan coil units, and ducted HVAC systems where freeze protection of water or glycol coils is required. The 20-foot sensing element is routed across the face of the coil in a serpentine pattern to average the air temperature and detect any localized cold spots that could indicate freezing conditions. When the sensed temperature drops to the cutout setpoint, the SPST contact opens, shutting down the system and triggering an alarm or lockout as wired.
Specifications
- SKU: A11A-1
- Brand: Johnson Controls
- Voltage: 24 to 277Vac
- Switch Configuration: SPST, Open on Low
- Reset: Manual
- Cutout Range: 35°F to 45°F
- Differential: 12°F Fixed
- Capillary Length: 4 feet
- Sensing Element: 1/8″ x 20 feet
