Freeze-protection electric plenum heaters have a set of normally open (NO) contacts that can send a signal to an optional alarm device that activates if the heater cycles off on its over-temperature safety control. It notifies users before freezing occurs, so they can address the issue before sensitive equipment can be damaged. These units heat hard-to-access or concealed areas like plenum spaces that hold utilities, crawl spaces, or water closets. They're ceiling mounted using a bracket or threaded rod mounting.

General purpose electric plenum heaters can be installed for free-air discharge or with a duct system to supplement central heating. They heat hard-to-access or concealed areas, such as between a finished and drop ceiling, a plenum space, or other space where there is limited room. The heaters can be rotated on their axis, but they must be suspended horizontally and independently supported. They cannot be mounted vertically.

These accessories are used to help install and enhance the capabilities of electric plenum heaters.