Aci A/FS-2 Low Limit Freeze Stat 2 Spdt Manual Reset

Product Description

The ACI A/FS-2 is a low-limit freeze protection thermostat designed to safeguard air handling units and HVAC systems against coil freeze-up and cold-air damage. It uses a 20-foot capillary sensing element that averages temperature across its full length, triggering shutdown before a freeze condition can damage equipment. On a trip event, the unit requires manual reset, giving the technician a clear indication that an abnormal condition occurred before the system is returned to service. Two sets of SPDT contacts provide output flexibility for controlling fans, dampers, or alarm circuits at 120 VAC or 240 VAC supply voltage.

The A/FS-2 is suited for residential and light commercial air handling units, makeup air units, and rooftop equipment where freeze protection is required. The 20-foot capillary is routed across the face of a coil or across an air stream to detect any cold spot along its length. Licensed HVAC technicians install this device as part of a low-limit safety circuit, typically wired in series with the supply fan contactor or unit control board to shut down airflow on a freeze event.

Key Features

• 20-foot capillary sensor averages temperature across the full sensing length for broad coil coverage
• Manual reset operation flags freeze events and requires technician acknowledgment before restart
• Two sets of SPDT contacts allow simultaneous control of multiple outputs such as fan and damper or fan and alarm
• Compatible with 120 VAC and 240 VAC supply circuits
• Mechanical display with no electronic components to fail in cold or wet environments
• Low-limit type thermostat purpose-built for freeze protection applications

Compatibility

Designed as an OEM-style replacement or new-installation freeze stat for residential and commercial air handling units requiring a low-limit, manual-reset capillary thermostat with dual SPDT output contacts.

Installation Notes

Installation should be performed by a licensed HVAC technician. Disconnect and lock out all power to the air handling unit before wiring the thermostat contacts. Route the capillary element across the full face of the coil or air stream in a serpentine pattern without kinking or sharp bends. Verify supply voltage matches the unit rating and confirm contact wiring against the unit wiring diagram before restoring power.

Technical Specifications

• Type: Low Limit Freeze Thermostat
• Output Contacts: 2 Sets SPDT
• Supply Voltage: 120 VAC, 240 VAC
• Capillary Length: 20 feet
• Reset Type: Manual
• Display Type: Mechanical

Standard Information

• Brand: ACI
• Manufacturer Part Number: A/FS-2