The Fenwal 27121-20-190 is a stainless-steel Detect-A-Fire overheat detector designed to provide reliable thermal protection in HVAC and heating equipment. It monitors surrounding temperature and activates its normally open contacts when the temperature reaches approximately 190°F, allowing connected control or safety circuits to initiate an alarm or shutdown. It is commonly used with... https://www.partshnc.com/fenwal-27121-20-190-detector-heat-s-s-190-f