The 121275 is a versatile normally closed safety thermostat designed exclusively for 2 Reznor heater types: gas unit heaters and waste oil heaters. It serves as a critical overheat protector—remaining closed during normal operation, triggering at 275F to shut off power when vents or flues are blocked, and requiring manual reset after cooling to prevent unsafe restarts.
For Reznor Gas Unit Heaters (F-series): Fits models F75, F100, F125, F165, F200, F250, F300, F400 — ideal for warehouses, workshops, and industrial spaces relying on forced-air heating.
For Reznor Waste Oil Heaters: Compatible with RA 140/235/350/500, RAD 140/235/350/500, and Venturion 225/325 — perfect for facilities recycling waste oil for cost-effective heating.
It integrates seamlessly into both heater safety circuits, no extra modifications needed. For safety: Always disconnect power before setup and wear insulated gloves. Double-check your heater’s type and model to ensure a proper fit.
Package includes: 1 x 121275 Heater Safety Switch (NC, 275F Manual Reset).
