the 79J21 is the current OEM designation and is fully backwards compatible with legacy part numbers 79H21

providing flexible SPDT control for heating or cooling signals

Its surface-mount housing and durable construction make it a standard choice for furnace safety limit maintenance and HVAC rollout switch replacement tasks

Optimal Lead Length: 24-inch length provides necessary slack for clean wire routing and strain relief within the cabinet

Does the unit include overcurrent protection

Maxon 18118 Spark Ignitor Els PW 17895 the 79J21 is the currentThe Maxon 18118 Spark Ignitor is a critical high voltage combustion ignition component engineered specifically for industrial gas fired equipment, including Maxon burners, gas turbine engines, and high capacity boilers. Featuring a precision 18mm electrode, this ignitor delivers a consistent high energy spark to ensure reliable fuel air mixture ignition, eliminating the need for inefficient pilot lights and reducing instances of incomplete combustion.