Once the system cools to the 35°F close point

the small black cap should be loosened one full turn to allow air to escape

preventing catastrophic pressure buildup

The 'X' in 3VX450 indicates a notched or cogged construction

Utilize the SPDT relay terminals and spade connectors to break the burner circuit or trigger an alarm when the liquid level falls below the probe tip

Resideo R4222D1013 Relay 318172-701 Once the system cools toThe Resideo R4222D1013 Relay is a heavy duty, field proven switching solution designed for refrigeration, air conditioning, and industrial automation equipment. This 120V DPDT General Purpose Relay features a double pole, double throw contact configuration, allowing for simultaneous control of multiple circuits. Built with a laminated magnet construction for superior operating efficiency and an untaped coil for cooler performance under continuous