Responded to no-heat call for a boiler that had repeatedly shut off on high temperature safety limit. Observed system operation through both domestic hot water and fan coil heating cycles, confirming proper modulation and temperature control. Adjusted target temperature from 190°F to 185°F to prevent overshooting the 200°F limit. Noted main pump vibration and potential issues with domestic water pump flow, though system was functioning properly at time of departure.
