STI STI-1200A-HTR Heated Enclosure with Fire Label
Overview
The STI-1200A-HTR is a heated enclosure designed to protect UL 38 and 2017 fire alarm initiating devices in extreme cold. It maintains device operating temperature down to -70°F (-57°C) using a continuous-run fan paired with thermostatically cycled heating elements. The 4-inch deep back box accommodates standard surface-mount fire alarm pull stations and addressable initiating devices. UV-stabilized polycarbonate cover resists discoloration and provides visibility of the protected device. NEMA 3R rating delivers weather protection against rain, sleet, and external ice formation — essential for outdoor installations where device failure from freezing would violate fire code supervision requirements.
Compatibility
The STI-1200A-HTR enclosure accommodates UL-listed fire alarm initiating devices meeting UL 38 and UL 2017 standards, including addressable units. It is engineered to work with standard fire alarm pull stations and notification appliances requiring temperature protection in cold climates. Verify that your specific initiating device (pull station, detector, module) fits within the 4-inch back box depth and electrical termination footprint before ordering. Consult the installation sheet supplied with your fire alarm control panel to confirm compatibility with your specific model.
Installation Notes
The low-temperature monitoring thermostat closes the circuit at +32°F (0°C) and opens at +50°F (+10°C), allowing the heater to cycle as needed while minimizing power draw. The enclosure requires 24VDC supply wired per NEC Article 725/760 and NFPA 72. Conduit and raceway entries must be sealed as close as possible to the enclosure to prevent cold air infiltration and condensation. The fire alarm supervisory control module must be of the latching type. UL/ULC listing does not require standby or secondary power for 110 or 240VAC 50/60Hz heater operation. Independently tested to -102°F (-73°C) for margin beyond the -70°F rated floor. The fan runs continuously; design your power budget and thermal pathway accordingly.
