Duct Limit SwitchOperating within air ducts across the globe, Firestat duct controls play an important role in HVAC systems, ensuring safety by halting equipment if air temperatures exceed pre-set limits. These switches are key in specialized HVAC setups and Building Automation Systems (BAS). For additional help installing your Firestat, contact us.

Duct Limit Control Installation Procedure

  1. Determine Installation Locations: Identify critical temperature spots in the ductwork, such as downstream from electric heaters or areas near flammable materials.
  2. Voltage Compatibility: Firestat’s can function in both low voltage and line voltage circuits. Ensure correct wiring to interrupt both heat source and blower circuits when the duct air temperature surpasses the set limit. When multiple Firestats control a single heat source, connect them in series.
  3. Step-by-Step Installation: Temperature Adjustment: Set the temperature dial to the desired limit.

Placement: Install the Firestat downstream of air flow in the air duct system.
Wiring: Connect the Firestat to the fan following the provided wiring diagram.

For detailed assistance, refer to the wiring diagram here.

Determining Temperature Settings

After installation, determining the optimal temperature setting is crucial for effective operation. Follow these steps:

  1. Temperature Assessment: Measure the air temperature next to your furnace while it’s running.
  2. Adjustment Calculation: Add approximately 40°F to the measured temperature to accommodate fluctuations. This sum becomes your recommended Firestat setting.

TC1051A3CTemperature Adjustment Procedure

  1. Cover Removal: Gently detach the cover by pressing on the sides of the switch, exposing the internal components.
  2. Dial Adjustment: Loosen the screw to adjust the selector to the desired temperature within the range of 100°F to 250°F. After selecting the temperature, securely tighten the screw to set the dial.
  3. Cover Replacement & Installation: Place the cover back onto the switch, ensuring proper alignment. Reinstall the Firestat into the duct system.

Upon leaving the factory, Firestat switches are preset to 125°F but offer an adjustable range from 100°F to 250°F.

By following these guidelines, you can ensure efficient installation and operation of your Firestat duct controls, enhancing safety and functionality within your HVAC system.

Talk to a product specialist today!

CEMCO Duct Limit Switches

The Firestat Duct Fan and Limit Thermostat Switches operate using the same physics to ensure HVAC safety. A helix bi-metal element senses a rapid temperature change. When the temperature changes the bi-metal expands and triggers a snap action switch and either opens or closes a circuit. These switches are commonly installed in air ducts designed to shut down heating, air conditioning and ventilation equipment in apartment complexes and other multiple dwelling units when air temperature exceeds the set point.

UL & cUL Approved
Made in the U.S.A.