Identify elusive Btus via calculations

摘要

"Ask him, he knows about indirect water heaters," heard as I entered the no-spin zone: a local supply house where a competitor was seeking help from his inside salesman. "What's the issue?" "I installed a boiler with five zones of radiant heating and an indirect war-ter heater," said my friend. "They're running out of hot water during cold weather - worked great all summer."