Customer reported insufficient heat in the first-floor master bedroom. Upon inspection, I found the oil-fired Viessmann boiler supplying multiple cast-iron radiator hot water loops throughout the home. The system is also piped into a separate mechanical room with an additional manifold and large storage/storage buffer tanks connected to the boiler. Based on system layout, heating load, and current performance, the oil-fired Viessmann boiler appears undersized for the overall demand of this home when operating as the sole heat source. The boiler is running and attempting to satisfy all zones; however, due to the size of the residence and the number of heating loops, it is likely at or beyond its effective capacity. This would explain the lack of heat in certain areas, including the first-floor master bedroom. Customer reported oil usage of approximately 250 gallons every two weeks. They also stated that the previous owners relied heavily on the wood boiler system and used minimal oil
