Published: March 24, 2020 - by Dan Holohan

Categories: Hot Water


In this excerpt from his Classic Hydronics seminar, Dan Holohan teaches us about Mark Honeywell’s Heat Generator. In the early days of hot water heating, Mark Honeywell invented a device that would allow a hot-water system to work at temperatures as hot, or even hotter, than the steam systems of the time, but still be open to the atmosphere, which made them safe. If you encounter one on the job, please be cautious because it is filled with pure mercury.

Want to learn more? Read Dan Holohan’s book Classic Hydronics: How to Get the Most From Those Older Hot-Water Heating Systems.