18557-2 AERCO Boiler and Water Heater -20/240F REV ACT REMOTE BULB Normal Stocking Item in Our Warehouse AERCO 18557‑2 is the OEM –20°F to 240°F Reverse‑Acting Remote Bulb Temperature Control, and the grounded search results give us a complete, authoritative profile of the part. AERCO 18557‑2 Remote Bulb Temperature Control (–20°F to 240°F, Reverse‑Acting) — OEM hydronic temperature controller for AERCO boilers and water heaters. Features a remote bulb sensor for accurate temperature monitoring and reverse‑acting operation for high‑limit and safety applications. Engineered for precise, reliable performance in commercial HVAC and hydronic systems. 🔧 Core Identity & Function Part Number: 18557‑2 Component: Reverse‑Acting Remote Bulb Temperature Control OEM: AERCO Temperature Range: –20°F to 240°F Action: Reverse‑acting (output decreases as sensed temperature rises) This control uses a remote bulb sensor to monitor temperature at a distance from the control body (pipe, tank, duct, or heat‑exchanger surface). The reverse‑acting design is used when rising temperature must reduce output, such as: High‑limit safety functions Cooling‑valve actuation Hydronic system protection Combustion‑air or water‑temperature regulation Technical Specifications Temperature Range: –20°F to 240°F Action Type: Reverse‑acting Sensor Type: Remote bulb Application: Boiler control, commercial HVAC, hydronic heating Operation: Output decreases as sensed temperature rises Mounting: Bulb installs in process; control mounts remotely Applications Used in: AERCO commercial boilers AERCO commercial water heaters Hydronic heating systems requiring remote temperature sensing High‑limit or reverse‑acting control loops Typical replacement scenarios: Faulty or drifting temperature control High‑limit safety failures Remote bulb leakage or sensor failure Preventive maintenance on aging control assemblies
