Hydrolevel EL1220-SV Sensing Probe R-407C meaning the thermostat will engage

meaning the thermostat will engage either heating or cooling relays automatically to maintain the selected temperature without user intervention

Smith 100109424 specifications for a "drop-in" installation without field modifications

The EPDM components are specifically selected for their resilience in high-temperature water and steam applications

As a veteran-grade 2-stage control board

This specific part number is common in various Mitsubishi Electric HVAC equipment

Hydrolevel EL1220-SV Sensing Probe R-407C meaning the thermostat will engageThe Hydrolevel EL1220 SV is a specialized low water cut off (LWCO) sensing probe designed for high performance liquid level monitoring in hydronic heating and steam boiler systems. Featuring a rugged short ceramic insulator, this 45 221 part number is engineered for tight clearance installations where standard probes may interfere with internal castings or piping. The 1 2" NPT threaded connection ensures a secure, leak proof seal, while the 2 1 16"