slip-free connection between the stepper motor drive and the valve stem

The non-pcb

such as a severely clogged furnace filter

and WD/HD variants

Hardened Construction: Housed in a flame-retardant enclosure to meet safety standards for HVACR electrical components

Reznor 131450 Cut Off slip-free connection between the stepperThe Reznor 131450 Energy Cut Off (ECO) is a mission critical safety limit designed for industrial and commercial gas fired unit heaters. This OEM safety device functions as a fail safe by monitoring internal temperatures and automatically interrupting the heating cycle if conditions exceed 152C (306F). In the field, a tripped ECO often indicates airflow obstructions, incorrect gas pressure, or restricted ventingpreventing catastrophic equipment damage