Editor’s Note: This month’s Hydronics Workshop column marks the 25th anniversary for John Siegenthaler as a Plumbing & Mechanical columnist. John’s very first columns — all the way back in 1996 — used to be sent in by mail on floppy discs. We’ve come a long way together, so please join me in thanking John for his 25 years of sharing his vast knowledge with you, our readers. I also want to take the time thank our loyal readers for making Hydronics Workshop the most-read column on www.pmmag.com. Watch for a new, free eBook containing John’s most-read and favorite articles from Plumbing & Mechanical and PM Engineer to be released later this year.