Thermocouple Upon arrival inspected boiler, found pilot light out. Tried to relight pilot multiple times. Pilot won’t stay lit. Bad thermocouple and hat needed to be replaced. Replace thermocouple. Boiler is on/ running. Ran and monitored boiler operation- Normal. System back up to normal operation and left operating @ this time. Recommending to customer to follow up with routine maintenance. Recommending to customer to upgrade standing pilot to spark ignition View visual findings from this job here - https://visionshare.xoi.io/?id=XA-EE1C-1B2EBF9F0033455B913DC5D09366518E