this specific unit is engineered for two-stage operation

as well as the narrower 4L and A series belts

making it a direct-fit solution for many modern hydronic systems

it is the standard for residential HVAC repair and light commercial heat pumps

quiet operation while providing superior tolerance to slipping and minor misalignment compared to raw-edge alternatives

Functional Devices RIBMNU1S Relay R-407A this specific unit is engineeredThe Functional Devices RIBMNU1S Relay is a professional grade 15 Amp pilot relay designed for high reliability switching in BAS, HVAC, and lighting control applications. This track mounted modular relay features a versatile triple voltage coil, allowing for seamless integration into systems utilizing 10 30 Vac Vdc or a standard 120 Vac power source. Engineered for long term field performance, it utilizes a SPST (Single Pole Single Throw) contact