Published: March 9, 2020 - by Dan Holohan

Categories: Steam


Many old steam-heating systems are oversized as a result of the Spanish Influenza pandemic of 1918-19. The flu killed 50 million people worldwide. People became deathly afraid of the air in their homes, in their workplaces, in their houses of worship. They began to open their windows to let in fresh air, and this had a dramatic effect on central heating. You can see it in the engineering books published after 1920. The authors wrote of the Fresh Air Movement and cautioned engineers to specify boilers and radiators that will be large enough to heat the building on the coldest day of the year, with the windows open.

In this excerpt from Dan Holohan’s Dead Men’s Steam School seminar, Dan shares how to cut a radiator’s output if your radiators are oversized and your rooms are overheating. He talks about paint, including why most radiators are painted silver. He also discusses radiator enclosures.

Want to learn more? Read Dan Holohan’s book The Lost Art of Steam Heating Revisited.