Most of America's classic hydronic systems are older than we are, and they've gone through changes over the years, some of them painful changes. Many of these systems went in before we knew as much as we know today about hot-water heating. So let's talk about how Classic Hydronic systems work, how they've changed over the years, and what we can do right now to get the most out of them without spending a fortune. (Oh, and I promise you a few great stories along the way.) My goal is to make you "see" inside those older systems, and to be able to do stuff that others say can't be done. If I can do that, you will be nodding your head and smiling at your newfound knowledge, and I will be in a state of bliss. Dan Holohan