Firestat

Fixed Temperature Duct Limit Switch

Fixed Duct Limit SwitchFixed Temperature Duct Limit Switch

The TC Firestat limit switches are available as a fixed temperature option – or as many know it as the 4PU Grainger Series. The fixed duct limit switch offers the same benefits as our other duct limit switches, but comes preset at the required temperature. Our standard fixed temperatures include, 125°F, 165°F or 200°F. See part number guide below. Other custom fixed temperature options are available, please contact us.

The fixed temperature duct limit switch features a helix bi-metal element that senses rapid increases in temperature, such increases often caused by fire in a HVAC duct system. The duct limit switch operates a single pole, single throw (SPST) switch that opens when temperature rises. The enclosure has an ambient temperature of -40°F to 190°F. And the element’s ambient temperature is 350°F.

The duct limit switch is supplied with a manual reset lever, which requires human intervention to reactivate the limit switch after the high temperature condition has cleared.

Our standard fixed temperature limit switch is available with a 5″ insertion element. Other element lengths are available, please contact us for custom options.

Commonly the firestat duct limit switches are installed in air ducts to shut down HVAC equipment when air temperature exceeds a pre-set limit. These duct high temperature limits are indispensable in specialized HVAC applications and Building Automation Systems.

Part Number Description Range Factory Set Switch Action
TC2051A1253C18 (4PU53) Manual Rest, Fixed Temperature 5″ Element 125°F 125°F Open on Rise
TC2051A1653C18 (4PU54) Manual Rest, Fixed Temperature 5″ Element 165°F 165°F Open on Rise
TC2051A2003C18 (4PU55) Manual Rest, Fixed Temperature 5″ Element 200°F 200°F Open on Rise

For more information about our fixed temperature duct limit switches, view our catalog page or contact us.

To purchase a preset duct limit switch, visit our online store or contact us for quote.

Adjustable Duct Limit Control Catalog PagesPurchase fixed temperature duct limit controlsContact Senasys about adjustable limit controls