During the most recent round of Department of Energy funded energy conservation efforts for low income multifamily buildings, numerous older buildings (circa 1970) received new physical plants to replace the older inefficient systems that were installed during the cheap energy era. Most of these buildings contained the typical cast iron natural gas fired boilers. They were operated at one set temperature, typically 180°F. In most cases, the boilers also provided Domestic Hot Water (DHW) thru either a side arm heat exchanger or an immersed coil inside of the boiler....More