Marley Engineered Products 4520-0011-002 Limit Switch and Ducane equipment to ensure

and Ducane equipment to ensure plug-and-play installation without field modifications

Direct Replacement: replaces cracked or leaking collector boxes to resolve furnace pressure switch lockout issues

making it the standard replacement for various mid-to-high-efficiency Lennox units

Standard 325-3 models often require a separate 12A09 vent limiting device for indoor use to meet code without piping a vent line

though typical pilot signals range higher depending on the specific module

Marley Engineered Products 4520-0011-002 Limit Switch and Ducane equipment to ensureAs a seasoned technician, you know that a reliable furnace limit switch is the primary line of defense against heat exchanger failure and fire hazards. The Marley Engineered Products 4520 0011 002 is a high performance linear limit protector designed for precision in demanding industrial and commercial heating applications. This 325F CO AUTO limit switch is engineered to monitor temperatures within the plenum and automatically interrupt the heating