The ZoneFirst PIRR is a 24Vac 4PDT Plug-In Relay engineered as a direct high-performance replacement for RR and RMABS relays

Its mid-point ground configuration enhances circuit stability

Improved Seating: Eliminates steam loss and gas bypass by ensuring the valve head aligns perfectly with the seat

extending the functional life of the contacts

making it the reliable choice for maintaining water-source heat pump integrity in commercial or residential geothermal applications

Siemens Industrial Controls 3RH2921-1DA11 Switch R-410A The ZoneFirst PIRR is aThe Siemens 3RH2921 1DA11 is a high performance lateral auxiliary switch block specifically engineered for the expansion of control circuit contacts. Designed for veterans in the field, this Sirius auxiliary contact features a robust 1NO + 1NC (1 Normally Open and 1 Normally Closed) configuration, providing essential feedback for motor control logic. Its side mount architecture allows for a space efficient 10mm profile, attaching seamlessly via snap