The Honeywell High Limit Aquastat Controller - L4006E1000 Boiler (Resideo L4006E1091) is a dependable high-limit temperature controller designed to protect hydronic heating systems like boilers and storage tanks by limiting liquid temperatures within a safe range. It operates over a 130 °F to 270 °F (54 °C–132 °C) range and uses a manual reset mechanism for added safety, ensuring the ... https://www.partshnc.com/l4006e1091-resideo-aquastat-mr-130-270f-openris