Lochinvar & A.O. Smith 100208514 Relay 30067439-890 If your valve lacks this

If your valve lacks this feature

the S352AA-2 supports both wall and DIN rail mount configurations

While many residential setups utilize a single sensor

This stem utilizes a dual-thread configuration with 5/16-18 NPT for the valve side and 3/8-16 NPT for the float side to accommodate standard industrial float balls

This usually occurs after repeated failed defrost attempts and must be manually cleared by cycling the 24V power to the control circuit

Lochinvar & A.O. Smith 100208514 Relay 30067439-890 If your valve lacks thisThe Lochinvar & A. O. Smith 100208514 Relay is a critical 24V electromagnetic control designed for precise low voltage circuit switching in commercial and residential hydronic systems. As the direct replacement for RLY2903, this OEM component ensures seamless HVACR system compatibility when interfacing between thermostat controllers and high load mechanical parts. This 24VAC relay is frequently utilized in boiler control boards and water heater wiring