Performed hearing maintenance on two hot water boilers remove and cleaned burners and standing pilot assembly. Replaced both thermocouple and clean burner trays checked expansion tanks and automatic water filter checked electrical connections and mechanical components check natural gas lines from shut off valve to gas valve also checked for carbon monoxide, none detected Left system working. View visual findings from this job here - https://visionshare.xoi.io/?id=XA-A243-9D657A5990AE47F0A1392EE691E0451A To replace the thermocouple