For years we have designed boiler rooms consisting of two oversized boilers with fully modulating burners. The idea was that the boilers could “loaf” along at low fire because we were told they were more efficient at low fire. I think it is time to rethink that strategy.
According to the EPA, “Boilers are most efficient when operated between 50-80% and boiler efficiency drops significantly when operated below 50%.” I know that this may require a paradigm shift but bear with me while I explain.