Plumbing & Mechanical columnist Ray Wohlfarth has a new book on the service of hydronic and low-pressure steam boilers titled, “Lessons Learned Servicing Boilers.” The book is filled with almost 300 pages of tips, rules of thumb, formulas and jobsite anecdotes. The book covers such topics as understanding combustion readings, leak-testing gas valves, troubleshooting boiler controls, understanding flame safeguards, how a horse can help with a leaking boiler and more than 60 pages of heating formulas.