and MMII4-105 boilers

Dual-Detector Support: A single Carrier HK28ZT001 board can manage up to two smoke sensors

While the 710 series is versatile

and S3 terminals for 10K Type II remote indoor sensors

Its simplified mechanical design reduces failure points

Functional Devices RIB2421C-N4 Relay R-134A and MMII4-105 boilersThe Functional Devices RIB2421C N4 is a professional grade enclosed pilot relay engineered for demanding HVAC, building automation, and industrial control applications. This 10 Amp SPDT relay features a multi voltage coil capable of accepting 24 Vac dc or 120 277 Vac, providing unmatched versatility for field installations. Housed in a rugged NEMA 4X enclosure, this unit is specifically designed for wash down environments or outdoor exposure where