Firestat Duct High Limit Switches

Protect HVAC Systems from Dangerous Overheating
Manual Reset Duct High Limit Controls for Commercial, Industrial, and Multi-Family HVAC Applications.

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Products

Adjustable & Fixed Temperature Models available with multiple probe lengths and other custom options.

Certified

UL listed & meets requirements in Section 907.3.1. of the North Carolina Mechanical Building Code.

Highly Trusted

Firestat duct high limit controls are trusted by HVAC Contractors, OEMs and distributors.

Made in U.S.A.

Firestat duct high limit switches are manufactured in Eau Claire, Wisconsin.

Fast Shipping

We strive to meet a two week lead time for low volume orders, with stock options available.

Direct Customer Support

Talk directly to our technical support and customer service team.

Adjustable and Fixed Temperature Models

Duct high limit controls are available with either adjustable or fixed temperature settings.

Firestat models are field adjustable within a temperature range of 100°F to 250°F and are available with 5-inch, 7.5-inch, or 11-inch bi-metal insertion elements. Custom element lengths, such as 3-inch, are also available upon request.

The TC-205 Duct High Temperature Limit Switch is a fixed-temperature model featuring a 5-inch element, offering consistent performance for standard applications.

Adjustable Temperature Models

TC1051A3C, TC1081A3C, TC1001A3C

An adjustable Firestat can be set within a temperature range of 100°F to 250°F.

Adjustable controls can be useful when the appropriate temperature limit depends on the operating temperature of a particular HVAC system.

Adjustable Duct Control
  • 100°F to 250°F Temperature Range
  • Service & Replacement
  • Manual Reset
  • 5″, 7.5″, 11″ Probe Length
  • Custom Options Available
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Fixed Temperature Models

TC1051A3C, TC1081A3C, TC1001A3C

Fixed-temperature controls are factory calibrated to trip at a specific temperature.

A fixed-temperature control can be a good choice when the required trip temperature is already established by the equipment design or application requirements.

Firestat Duct Control, Duct High Limit Switch
  • Factory Preset
  • OEM Production
  • Manual Reset
  • 5″ Probe Length
  • Custom Options Available
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Made-in-USA Duct High Limit Switches for Commercial HVAC

UL Recognized duct temperature limit controls that automatically shut down HVAC equipment during overheating conditions. Available in adjustable and fixed-temperature models with fast lead times and engineering support.

  • 100°F to 200°F Temperature Range
  • Adjustable and Fixed Temperature Models Available
  • 4.9 FLA @ 240 VAC / 9.8 FLA @ 120 VAC / 29.4 LRA @ 240 VAC / 58.8 LRA @ 240 VAC
  • 5″, 7.5″ or 11″ Element Lengths
  • Single-Pole, Single-Throw (SPST)
  • Opens on Temperature Rise
  • Manual Reset
  • UL Recognized
  • Meets North Carolina Building Code Section 907.3.1.


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Testing your duct limit switch

Technical Resources

VIEW PRODUCTS

Compare models of duct high limit controls.

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INSTALLATION GUIDE

View our guide to install your firestat.

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BUILDING CODES

Find a list of building code that require firestats.

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COMMON APPLICATIONS

Learn more about where our duct high limit switches are used.

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FAQs

Most of your questions, answered.

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distributors

Work with a distributor to purchase a firestat.

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contact us

Contact our technical support team.

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company news

Learn more about what’s new at Senasys.

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Frequently asked questions

What is a duct high limit switch? When is a Firestat required? What’s the difference between adjustable and fixed? Are Firestat controls UL recognized? Can I order custom temperatures? How quickly do you ship? Where are Firestat controls manufactured? Do you work with OEMs?

A Firestat is a temperature-activated safety switch installed in HVAC ductwork. When duct temperatures exceed the preset limit, the switch interrupts power to the heating equipment and blower to help reduce the spread of heat, smoke, and fire through the duct system.

Visit our product page to learn more.

A duct high limit switch protects HVAC equipment and building occupants by shutting down heating equipment if excessive duct temperatures occur due to equipment malfunction or fire conditions.

Visit our applications page to learn more about where these products are commonly found.

Adjustable models

  • Temperature can be changed in the field
  • Ideal when system temperatures vary

Fixed models

  • Factory calibrated
  • No field adjustment
  • Excellent for standardized installations

Visit our product page to learn more about available options.

Yes.

Firestat controls are UL recognized and manufactured in the USA. Refer to the individual product pages for specific certifications and ratings.

Yes. Firestat offers a variety of customization options to meet the needs of OEMs, equipment manufacturers, and specialized HVAC applications.

Available customization options may include:

  • Fixed or adjustable temperature settings
  • Multiple probe lengths to accommodate different duct sizes and installation requirements
  • Custom temperature calibrations for specific applications
  • Private labeling and custom branding
  • OEM-specific configurations
  • Custom packaging and labeling
  • Application-specific electrical and mounting options

Our engineering and manufacturing teams work closely with customers to develop solutions that meet their performance, installation, and regulatory requirements.

If you have unique application requirements or need a custom duct high limit control,  contact our team to discuss your specifications. We’ll help determine the best configuration for your project.

Firestat strives to ship orders as quickly as possible. Many standard products are in stock and can ship within 1–2 business days, while lead times for larger quantities, custom configurations, or OEM orders may vary.

Shipping times depend on several factors, including:

  • Product availability
  • Order quantity
  • Standard or custom configuration
  • Shipping method selected
  • Delivery destination

Once your order has shipped, you’ll receive a shipping confirmation and tracking information (when applicable).

If you have an urgent requirement or need expedited shipping, please  contact our sales team before placing your order. We’ll do our best to accommodate your schedule and provide the fastest available delivery.

CEMCO firestats are now manufactured by  Senasys in Eau Claire, Wisconsin, U.S.A.

Yes. Firestat offers OEM pricing for equipment manufacturers, distributors, and customers purchasing production quantities.

OEM pricing is based on factors such as:

  • Annual usage or forecasted volume
  • Product configuration
  • Standard or custom specifications
  • Packaging and labeling requirements
  • Long-term supply agreements

In addition to competitive pricing, Firestat supports OEM customers with custom product configurations, private labeling, engineering assistance, and reliable manufacturing in the USA.

If you’re interested in OEM pricing,  contact our sales team with your application details, estimated annual volume, and product requirements. We’ll review your project and provide a customized quotation based on your needs.


Who We Serve

High Temperature Limit Solutions for:

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HVAC & Mechanical Contractors
Building Maintenance
HVAC Distributors
Original Equipment Manufacturers

Testimonials

For over 20 years, Firestat has manufactured duct high limit controls used throughout North America. Every control is manufactured and tested in Wisconsin by Senasys and supported by engineers with decades of temperature control experience.

Serving the HVAC industry since 1980.
Over 30,000 Firestats installed annually.

Purchased one of these units for my furnace. It is a quality product and great customer service provided as well.

Tyler A.

Home Owner

We needed 11 duct controls for an inspection of an apartment building. Company was easy to work with and helped us find what we needed to pass the inspection.

Alex R.

Contractor

I’ve recommended the firestat product offering to multiple companies I have worked for. It’s a great product, and the service the company provides is outstanding!

Anonymous

HVAC Distributor

Our Distributors

FIND A DISTRIBUTOR

Firestat duct high limit controls are trusted by contractors, manufacturers, distributors and maintenance teams across North America. If you prefer working with a distributor, visit one of our partner websites below.

DYNACON HVAC CONTROL
KELE DUCT LIMIT SWITCH

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    Our office hours are

    Monday – Friday

    8 a.m. to 4 p.m. CST

    Firestat Duct High Limit controls 
    (cemco)

    A Division of Senasys

    1435 International Drive

    Eau Claire, WI 54701 USA

    +1 (715) 620-1802

    [email protected]