0 System Sensor w/built in sounders — change out all detectors to new. (8) Heat Detectors 4350 $ 400 (3) Gas Alarm Sensors @ 175 $ 525 (6) Honeywell 5800CO Wireless Carbon Monoxide Detectors @ 150 $ 900 (12) System Sensor D4120 Duct Detectors with new Smoke Sampling Tubes @ 275 $ 3,300 Sampling Tubes — DSTS Five Foot Sampling Tubes