such as a severely clogged furnace filter

Universal Terminal Markings: Standardized coding matches most competitive brands like Honeywell

" this switch is performing its safety function

and Tempstar furnaces

Reznor 131450 Cut Off such as a severely cloggedThe 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