They are the same part

Zero Minimum Pressure: Operates reliably at 0 PSI inlet pressure

Is this switch compatible with all refrigerants

this power assembly offers a direct-fit solution for maintaining system efficiency and precise refrigerant metering in specialized cooling loops

When performing a vertical HVAC unit repair

Tekmar Controls 304P Relay Panel 322838-753 They are the same partThe Tekmar Controls 304P Relay Panel is a professional grade 4 zone switching relay engineered to manage up to four low voltage thermostats and four 120V circulating pumps in hydronic heating applications. Built for technicians who demand reliability in zoned radiant floor or baseboard systems, this hydronic zone control utilizes a microprocessor based design to coordinate calls for heat with precision. The 304P switching relay features RoomResponse