Reznor 121275 Block and SV9501 series

and SV9501 series

Built with a dry case and a black steel housing

Reliable Ignition: Supports proper flame impingement on thermocouples and flame sensors to reduce system downtime

While it is often found in systems with similar nominal voltages

Reznor 121275 Block and SV9501 seriesThe Reznor 121275 Stack Flue Block is a high limit safety component engineered specifically as an Energy Cutout Device (ECO) for commercial and industrial gas fired heating units. Designed to monitor the integrity of the ventilation system, this blocked vent switch acts as a critical failsafe by measuring exhaust temperatures at the flue. If the sensor detects a restriction, backflow, or overheating condition where temperatures reach the 275F trip